Functional Groups Guide – Organic Chemistry

September 8, 2020 By Leah4sci Leave a Comment

Complete Guide to Recognizing, Drawing, and Naming Functional Groups in Organic Chemistry

A functional group is a specific group of atoms that helps determine the chemistry and reactivity of the overall molecule. When classifying functional groups, we look at both the specific atoms present, as well as the manner in which they are connected to each other.

While there are an overwhelming number of functional groups to consider, this guide will focus on the groups you’re most likely to come across at the beginner orgo level, along with some common groups that will show up in later (orgo 2) reactions.

We’ll tackle these groups from lowest to highest priority looking at

Atomic makeup of each group
How to recognize and draw them
Key characteristics
How to name each group.

Recall that if more than 1 functional group appears on a molecule, the higher priority group is named in the suffix, and the lower priority group is ‘demoted’ to substituent status and named in the prefix.

Follow along with the Functional Group Priority Cheat Sheet as well as any specific functional group naming videos that are linked after the examples below.

The R Group

While the R group is not a functional group at all, it’s important to discuss it before we move on.

The letter ‘R’ pops up often in chemistry.
R represents a variable group, a changeable set of atoms that we don’t care to elaborate on at this moment.
For example, if you’ve studied the 20 common amino acids you’ll notice that the common amino acid structure has a backbone and an ‘R’ on the central carbon. That ‘R’ represents the 20 different side chains.
I like to think of the ‘R’ simply as the ‘REST’ of the molecule.

What does this have to do with functional groups?
Functional groups can show up on all sorts of carbon chains. But if the focus of our discussion is a functional group, we don’t want to get distracted by all of the carbons, hydrogens, or anything else in the parent chain.

Instead, we replace the entire parent chain with the letter R and attach the functional group to it.

For example, if I want to show you that OH is an alcohol, I will write that as R-OH.
R = rest of the molecule, OH = the group we’re looking at attached to the ‘rest’ of the molecule.
Ready? Let’s begin!

Alkyl Halide Substituent -X

The alkyl halide is considered a substituent rather than a functional group.
However, they are so reactive and show up so frequently in organic chemistry that we’d be remiss to skip over them.

While there are five halogens on the periodic table, I have yet to come across Astatine in over a decade of teaching Organic Chemistry.
Instead, focus only on Fluorine, Chlorine, Bromine and Iodine.
The letter ‘X’ acts as the ‘variable halogen’ and can represent any of the above.

Recall from the Intro to Orgo videos that electronegativity increases up and towards the right, while size increases down and towards the left.

This makes fluorine the smallest and most electronegative halogen, and Iodine the largest and least electronegative.

To recognize this group in organic molecules, simply look for a line to F, Cl, Br, or I

Naming Alkyl Halides

Since halogens are substituents rather than functional groups, we include their name in the prefix.
Take the full halogen’s name, drop the ending and add ‘o’.
For example, iodine becomes ‘iodo’, chlorine becomes ‘chloro’.
Be sure to specify the number of the carbon on which the halogen appears.

For even more watch: Naming Alkyl Halides

The Nitro Functional Group -NO2

While not required knowledge for naming and drawing early in organic chemistry, it is a tricky group that tends to confuse students when studying resonance and reactions.

Why?
The nitro group appears to be a very innocent neutral N + 2 O combination.
But if you draw it out, you’ll notice there’s much more going on.

A quick Lewis structure attempt reveals 2 major resonance forms with a positive formal charge on the nitrogen and a negative charge resonating between the 2 oxygen atoms.
The resonance hybrid has a partially positive nitrogen and 2 partially negative oxygens.

Naming Nitro Groups

You may not be tested on this, but do recognize that if NO2 appears on your molecule, you simply add the prefix ‘nitro’.

Thioether Functional Group -SR

Many students won’t cover thioethers in organic chemistry, and those who do typically see them in late orgo 1 reactions.

Anytime you see the prefix ‘thio’, immediately think of sulfur.

Thioether, as the name implies, is a thio (or sulfur) version of the ether.
As we’ll see shortly, ethers have an oxygen between 2 carbon atoms.
Thioethers have a sulfur (rather than oxygen) between 2 carbon atoms.

To recognize this functional group in organic molecules, look for a carbon chain with an S stuck in the middle, or look for a carbon chain with an S-R coming off it.

Naming Thioethers

Thioether groups are named with an ‘alkylthio’ prefix, where ‘alkyl‘ represents any R group. For a common name, list the alkyl group on either side of the sulfur in alphabetical order and end with the word ‘sulfide’.

Ether Functional Group -OR

Ethers are molecules that contain an oxygen atom sitting between 2 carbon atoms.
Not to be confused with an oxygen atom single bound to a branched carbon chain
Think of this as an oxygen atom stuck into the molecule, breaking the carbon chains apart, rather than simply being attached to the parent chain as a substituent (though they’ll show up that way as well).
With oxygen bound to 2 carbon atoms, the ether is incapable of hydrogen bonding and exhibits overall lower polarity. This will come in handy when studying polar protic and aprotic solvents.

Naming Ethers

Like their sulfur counterparts, the ether group is an -OR group attached to the parent chain.
Ethers are named as ‘alkoxy’ groups: ‘alk’ for the shorter carbon chain, and ‘oxy’ for the oxygen atom.
For even more watch: Naming Ethers

Amine Functional Group -NH2 -NHR -NR2 -NR3+

The amine is a functional group containing a nitrogen single bound to the parent chain. Whereas the nitrogen in the nitro functional group was attached to two oxygen atoms, the nitrogen in an amine may have 0-3 additional carbon groups attached to it.

Amines are classified as primary, secondary, tertiary or quaternary based on how many TOTAL carbon atoms are attached to the nitrogen. This video goes into detail about a trick I use to identify the degree of substitution.
Primary, secondary and tertiary amines are neutral. Quaternary amines have a +1 formal charge, due to having 4 bonds and no lone pairs on the molecule.

While only primary and secondary amines are capable of hydrogen bonding, all neutral amines are fairly reactive due to the partially negative lone pair on the nitrogen atom.
Aminium ions (positive quaternary amines) are also reactive but more likely to GET attacked due to their +1 charge.

Naming Amines

As the highest priority functional group, amines get the suffix -amine.

As a lower priority group, amines get the prefix ‘amino’.

When naming the additional carbon groups on secondary and tertiary amines, name them as you would any carbon substituent (with a prefix added to the front of the name). Use the letter N to designate the position of the group, rather than a number on the carbon chain.
For even more watch: Naming Amines

Thiol Functional Group -SH

We’ve already seen ‘thio’ denoting sulfur in the thioether.
The difference here is that thiol ends on ‘ol’ telling us it’s an alcohol.
The thiol group is a ‘thio’ alcohol, or sulfur alcohol.
Thio = sulfur and ol = alcohol.
The sulfur atom is larger than oxygen making the thiol group less polar. Unlike alcohols, thiols are unable to participate in hydrogen bonding (due to their lower polarity).

Naming Thiols

While you may not be tested on naming thiols, you will have to recognize them BY NAME when presented in a reaction (starting with substitution and elimination – SN/E reactions).

As the highest priority group, thiols get the suffix -thiol.

As a lower priority group, thiols get the prefix ‘mercapto’.

For even more watch: Naming Thiols

Alcohol Functional Group -OH

If alcohol makes you think of wine, beer or liquor, you’re not too far off. These beverages all contain one specific type of alcohol: ethanol.

However, the alcohol group refers to a wider range of compounds, anything containing an -OH functional group bound to the parent chain.
Or should I say JUST an OH bound to the parent. As we’ll see with carboxylic acids shortly, larger functional groups may contain OH as part of their overall structure.
Oxygen is a very small and very electronegative atom. This makes oxygen-containing compounds polar, and makes the alcohol group, an oxygen bound to hydrogen, an ideal candidate for hydrogen bonding. This video has more on the physical properties of alcohols

Naming Alcohols

As the highest priority group, alcohols get the suffix -ol.

As a lower priority group, alcohols get the prefix ‘hydroxy’.

For even more watch: Naming Alcohols

The Carbonyl Group

While not a functional group itself, the carbonyl group is still worthy of our time given that it shows up in many of the upcoming functional groups. (You’ll see quite a few chapters dedicated to carbonyl reactions in Orgo 2)

The carbonyl group refers to a carbon double-bound to an oxygen atom.
The carbonyl group is capable of resonance where the pi bond collapses up towards the oxygen.
Carbonyl resonance

The charged resonance form is not very stable due to an incomplete octet on carbon, as well as the separation of charge between the positive carbon and negative oxygen.
So why do we care?

Recall from your resonance studies that molecules exist as a resonance hybrid, existing somewhere between contributing resonance forms. Therefore, the carbonyl resonance hybrid contains a partially positive carbon atom and partially negative oxygen. This partial separation of charge is crucial to so many upcoming orgo reactions.

But, before we dive into all of the carbonyl reaction chapters, let’s take a look at all of the carbonyl containing functional groups. There’s a LOT of them.

Ketone Functional Group -COR

The ketone functional group has a carbonyl sitting in the middle of a carbon chain. Think of this as a carbonyl bound to 2 R groups, or as an oxygen double-bound to a carbon somewhere in the middle of the chain.

‘Middle of the chain’ is your key identifier since the ketone is a carbonyl IN a molecule, rather than at the end of the molecule. (Those are coming soon).
My mnemonic for this: The ketONE doesn’t want to be alONE and so hides WITHIN the molecule.

Even though it’s pronounced ‘key’ + ‘tone’, it’s not spelled ‘keytone’. This is a fairly common mistake and one of my pet peeves.

Drawing Ketones

The ketone does not break up the carbon chain as we’ve seen with ethers or as we’ll see with the carboxylic acid derivatives like esters and amides. This allows us to draw a simple skeletal structure for the molecule, with 2 lines to oxygen at the ketone location.

Naming Ketones

As the highest priority functional group, the ketone gets the suffix -one.

As a lower priority group, the ketone gets the prefix ‘oxo’.

For even more watch: Naming Ketones

Aldehyde Functional Group -CHO

The aldehyde looks very similar to a ketone with one major difference:
Aldehydes are terminal functional groups.

Recognize the aldehyde as a carbonyl (C double-bound to O) at the end of the molecule, with a hydrogen rather than carbon (ketone) on the other side of the carbonyl.

If you see a carbonyl at the end of the molecule with nothing else, it’s an aldehyde.

Drawing Aldehydes

Aldehydes are drawn just like ketones, but the carbonyl is at the end of the molecule.
While H atoms usually don’t have to be shown in skeletal structure, many will show the terminal H on the aldehyde to help emphasize its terminality. Expect to see them drawn both ways as I’ve drawn above.

Naming Aldehydes

As the highest priority functional group, aldehydes get the suffix -al.

As a lower priority group, they get the prefix ‘oxo’ or ‘formyl’.
While both are correct, ‘oxo’ is more common.

For even more watch: Naming Aldehydes

But wait a minute.
If both ketone and aldehyde have the prefix ‘oxo’, how can we tell them apart?
How do we know if ‘oxo’ refers to an aldehyde or ketone?

Simple!
If the ‘oxo’ is on a terminal carbon, it must be an aldehyde which is a terminal group.
If the ‘oxo’ is on an internal carbon, then it must be a ketone.

Take a look at the example below
Notice how ‘oxo’ on carbon 7 is the very last carbon in the chain? This must be an aldehyde.
Notice how ‘oxo’ on carbon 5 is NOT at the end of the chain? This must be a ketone.

Nitrile Functional Group -CN

Nitriles or cyano groups tend to show up in reactions more than naming for most orgo students.
The nitrile group is a carbon triple-bound to a nitrogen atom, where the carbon rather than the nitrogen is attached to the parent chain.

A carbon triple-bound to a nitrogen by itself rather than attached to a carbon chain is simply a cyanide anion.
For example KCN = Potassium Cyanide dissociates into a K+ cation and the CN- anion.
The nitrile or cyano group will show up mostly in advanced orgo 2 reactions.

Naming Nitriles or Cyano Groups

As the highest priority functional group, nitriles get the suffix nitrile.
As a lower priority substituent, the nitrile gets a prefix of ‘cyano’.

Due to the suffix ‘nitrile’ and prefix ‘cyano’, the name of the group itself is often interchangeable between ‘nitrile’ and ‘cyano’.

The sp2 carbon may or may not be counted as part of your parent chain. I’ve seen conflicting information regarding if to count it, or if to simply assume the C in CN is part of the substituent.
Be sure to find out which option your professor is looking for.

Carboxylic Acid Derivatives

For our final detour, let’s discuss carboxylic acid derivatives.
Since we’re working our way up from low to high priority, we’ll see the carboxylic acid last.
But let’s jump ahead for just a moment.

The carboxylic acid contains both a double-bound oxygen (carbonyl) and OH group on the same carbon. However, the carboxylic acid can undergo reactions where the OH is replaced with another group, as you’ll see toward the end of orgo 2.

Since these groups are derived FROM the carboxylic acid, they are called carboxylic acid derivatives.
Let’s take a look at the 4 most common carboxylic acid derivatives that you’ll study in organic chemistry.

Amide Functional Group -CONH2 -CONRH -CONR2

The amide group is a carboxylic acid derivative where the OH is replaced by a nitrogen.
The amide is a terminal group with a carbonyl bound to nitrogen.
As with amines, the amide nitrogen can be bound to hydrogen, carbon, or both.

Drawing Amides

Amides are drawn like an aldehyde, with a terminal carbonyl. Instead of the H (aldehyde) add N, and then add H or C depending on the specific molecule in question.

Primary and secondary amides have highly polar bonds and are capable of Hydrogen Bonding making them soluble in water.
Tertiary amides are not capable of H-bonding due to not having any H atoms on the nitrogen.

Naming Amides

As the highest priority functional group, amides get the suffix -amide.

As a lower priority group (less likely to show up), amides get the prefix ‘carbamoyl’.

Amides containing alkyl substituents on the nitrogen are named just like amine substituents. Identify each substituent prefix, and use the letter N rather than a number to designate its location on the molecule.

The Acid Halide Functional Group -COX

The acid halide or acyl halide functional group comes from a carboxylic acid where the OH is replaced by a halogen or halide.
You’ll recognize the acid halide as a terminal group with a carbonyl bound to a halogen.
Acid halides are very unstable and highly reactive as you’ll see in your advanced orgo 2 reactions.

Drawing Acid Halides

Acid or acyl halides are drawn the same way as aldehydes but instead of an H at the end, you simply draw the specific halogen.

Naming Acid Halides

As the highest priority functional group, acid halides get the suffix -oyl halide (2 words) where the halide is replaced by the specific halogen present in the molecule.
For example ‘-oyl chloride’ or ‘-oyl bromide’.

Ester Functional Group -COOR

The ester functional group has an oxygen double-bound to carbon (carbonyl) along with an OR group attached to the same carbon.
The ester is a carboxylic acid derivative in which the OH is replaced by an OR.

Do not confuse esters with ethers despite the names AND groups being so similar.
Ethers (OR) have just ONE oxygen between carbon atoms. Esters have a carbonyl in addition to the OR.

As a helpful memory device, one student pointed out on YouTube that Ester is a female name. From an anatomical point of view, females have 2 ‘O’s up top… if you know what I mean.

Naming Esters

As the highest priority functional group, esters get the suffix -oate.
The R-group on the ester is named as a substituent before the actual name (as a separate word, rather than connected)

For even more watch: Naming Esters

Acid Anhydride Functional Group

The acid anhydride, often simply called ‘anhydride’, is a somewhat tricky group. The anhydride contains a carbonyl, bound to oxygen, bound to another carbonyl.

This is less confusing when you consider that this carboxylic acid derivative is created by combining 2 carboxylic acids and removing a water molecule. (2H + O) in the process.

Anhydrides are very unstable and highly reactive, and will show up in late orgo 2 reactions.

Naming Anhydrides

You likely won’t have to name anhydrides but just in case:
Symmetrical anhydrides, which have the same length carbon chain on either side, are named similar to carboxylic acids with the ending -oic anhydride.

Assymetrical anhydrides, which have different length carbon chains on either side, are named for both carbon chains in alphabetical order, each ending in -oic followed by ‘anhydride’

Carboxylic Acid Functional Group -COOH

Finally we get to the highest priority functional group: the carboxylic acid.
Carboxylic acids have a carbon atom double bound to oxygen (carbonyl) along with an OH single bound to that same carbon atom.

Do not confuse the carboxylic acid with an alcohol. If the OH is on a carbon that has nothing else, it’s an alcohol. If the OH is bound to a carbonyl carbon, it’s a carboxylic acid.

Carboxylic acids are fairly acidic due to hydrogen sitting on oxygen next to a carbonyl. When deprotonated, the resulting carboxylate anion is stabilized through resonance as shown below

Naming Carboxylic Acids

As the highest priority functional group, carboxylic acids will always be the suffix of your molecule. Additionally, as a terminal functional group, always assume the carboxylic acid is located at carbon #1. This means no numerical designator is required.

Name the parent chain for the number of carbon atoms, then add the suffix -oic acid.

For even more watch: Naming Carboxylic Acids

What do you think?

Do you feel better about Organic Chemistry Functional Groups having read through the entire guide? Why not test your knowledge with the Functional Groups Practice Quiz?

Need a quick review? Watch the functional groups summary video, or take a look at the functional groups cheat sheet below.

Organic Chemistry Functional Groups Cheat Sheet

Lewis Structure for Radicals

March 24, 2020 By Leah4sci Leave a Comment

This video shows you a quick, time-saving checklist for radicals in Lewis structures! It ensures you don’t miss anything when deciding WHICH atom most likely has the radical. You’ll also see it in action as it is applied to several examples.

(Watch on YouTube: Lewis Structures Radicals. Click cc on bottom right for video transcription.)

Links & Resources Mentioned In This Video:

Lewis Structure Checklist: https://leah4sci.com/lewis-structure-t…
Formal Charge Shortcut: https://leah4sci.com/formal-charge-for…
Organic Chemistry Basics Video Tutorial Series: https://leah4sci.com/orgobasics
Radical Resonance: https://leah4sci.com/radicals

<– Watch Previous Video:
–> Watch Next Video:

This is Video X in the Orgo Basics Video Series. Click HERE to view the entire series.

Cyclohexane Ring Flip and Boat Conformation

August 22, 2019 By Leah4sci Leave a Comment

Cyclohexanes are most stable in the chair conformation. This requires a ring flip to interconvert between the 2 chair conformations, with some funky (boat) intermediates.

This video walks you through the ring flip and boat conformations both with a model kit as well as how to draw the ring flip and boat on paper.

(Watch on YouTube: Ring Flip. Click CC for the transcription.)

Links & Resources Mentioned In This Video

Drawing Chair Conformations and Ring Flips for Cyclohexane Tutorial

<– Watch Previous Video: Chair to Double Newman Quiz Challenge Question Solution
–> Watch Next Video: Coming Soon

This is video 3 in the Chair Conformations Tutorial Series.

Would a Model Kit help you? Watch How to Use Your Organic Chemistry Model Kit.

What To Expect in Organic Chemistry

August 28, 2017 By Leah4sci Leave a Comment

Organic chemistry is one of the most difficult sciences you’ll take in undergrad.
Many students fail and have to take it again.

You’ve heard the rumors.

Perhaps you don’t believe them, or perhaps you’re terrified.

But what can you actually do about them?

The first step to conquering an unknown beast is understanding it.

By understanding what’s coming and knowing exactly what to expect, you’ll be better prepared to tackle this course.

First, read to find out why Organic Chemistry is so darn difficult.

Now let’s talk about what this course is all about.

How Organic Chemistry Differs From The Other Sciences

Up to this point, you’ve gone through both simple and difficult sciences.

In biology, you spent your time learning about systems and structures.

You memorized names, shapes, images, and perhaps some numbers and figures.
You may have dissected worms, frogs, fetal pigs, or even cats.

It wasn’t easy, and perhaps it wasn’t fun.
But it was straightforward.
There was nothing too tricky or crazy.

In general chemistry, you studied what makes science tick.

You learned concepts and reactions,
memorized terms and processes,
and studied a bunch of equations,
which you then spent hours applying and calculating.

Learn, understand, plug, and chug.

Physics was the same, but perhaps slightly more difficult.

In each of these difficult areas from free body diagrams to circuits and fluids, you had to invest the time to learn, but once you did, it was easy enough to follow.

It was a simple system.

Enter Organic Chemistry.

This may be one of the only classes where you’re asked to truly think and come up with steps.

There’s no easy way to memorize your way through this class.

In fact, memorization will only serve to confuse you,

because for every “rule,” there are a gazillion (ok, maybe only half a dozen) exceptions.

How to Succeed in Organic Chemistry

So how do you prepare for a class if you can’t study (read: memorize) the material?

Simple.

You go into everything with two questions:

Why?
How?

It’s not enough to learn the “what.”
You need to know the reason behind everything you learn!

So when things change or an exception surfaces,
you can apply what you’ve studied to unknown circumstances and reactions because you recognize the patterns of the reactions despite their format.

So what will you actually cover in Organic Chemistry?

For a detailed chapter/topics list with associated resources, be sure to follow along with my Organic Chemistry Syllabus Companion.

When the average student hears “organic chemistry,” they think of reactions and mechanisms.

Some students might think of synthesis and retrosynthesis, which is an advanced approach to reactions and mechanisms.

And yes, organic chemistry IS really just reactions and mechanisms.

Any additional concepts in the course simply

prepare you for reactions and and mechanism (intro topics) or
show you how to analyze your mechanisms and products (spectroscopy) to confirm those reactions and mechanisms.

The first week or two is more of a general chemistry review than organic chemistry.

In order to learn about the behavior of molecules and reactions,
you must, must, must, understand the structure, bonding, and other attributes of the molecule in question.

You’ll begin with the simple pre-reaction concepts:

You’ll learn about atoms and orbitals; hybridization and bonding.

You’ll learn about the basic molecules, including how to name them.

This will allow you to carry out reactions on exams when given a name instead of a structure.

Once that’s clear,

You’ll learn how to draw molecules using skeletal structure or bond-line notation.

This will save your sanity as you write and rewrite molecules for every step of the mechanism.

Most of this should have been covered in your general chemistry course, but most likely wasn’t.

And if was, you’ve likely forgotten anyway. That’s ok.

Next!

Resonance

The heart of Orgo 1 is about preparing you to learn mechanisms.
But first, you need an introduction to mechanisms: resonance.

But we can’t stop here.

You’ve got the structures, but let’s go more three dimensional.

How are these molecules studied? How do you look at them?

This is where conformational analysis comes into play:

Newman projections, chair conformations, and chirality/stereochemistry.

This is the level in which you take two-dimensional reactions on paper and bring them to life in the three-dimensional world.

It’s not just about what’s connected to what, it’s also about how.

Spatial awareness and understanding will be critical to reactions down the line.

Many students (like myself at first) have trouble seeing stick figures in 3-dimensions.
This is where a model kit (the one I recommend) is not only advised but highly recommended.

So long as you don’t fall into the trap –> Do NOT rely on your organic chemistry model kit

Mechanisms

Now that you have a good understanding of the baseline,
you will tackle some simple reactions and mechanisms,
including acid/base reactions, a topic you should remember from general chemistry.

What is a mechanism?

It shows you exactly how a reaction proceeds. Exactly which atoms/electrons attack, what they attack, which bonds break and which new bonds form. For every step of a reaction.

Organic chemistry doesn’t use those annoying ICE charts and buffer calculations (whew!)
Instead, organic chemistry looks at these reactions at the level of the reaction itself.

We know that H2SO4 dissociates in water: BUT HOW?

This is the start of your mechanism exposure. This is the key.

You’ll learn how to identify which atom does the grabbing and which atom gets grabbed; which molecule attacks and why.

This right here is what the rest of organic chemistry is about:

Mechanisms.
Mechanisms.
Mechanisms.

You’ll have a few odd topics thrown in here and there,

like spectroscopy, which is reading molecular analysis graphs.

You’ll review reaction energy diagrams, which should sound slightly familiar from general chemistry.

But the rest of it will be all about reactions and mechanisms.

How the heck are there enough reactions to fill two full semesters? What do you even cover in Orgo 2?

To put it simply: There are many, many reactions.

Undergraduate level organic chemistry barely scratches the surface!

The average student will have to know and repeat 50 to 200 mechanisms by the end of Orgo 2.

Many of them are very similar. For example,

Adding water to an alkene – oxymercuration.
Or adding an alcohol to an alkene – alkoxymercuration.
You’ll cover the main functional groups and their respective reactions.

Orgo 1 may cover the mechanisms for alkyl halides and radicals, perhaps even alcohols, ethers, epoxides, and phenols.

Then you’ll move on to Orgo 2 for more of the same: aromatic compounds, ketones, aldehydes, carboxylic acids, amines, and more.

And if you’re lucky (read: have an evil professor) you’ll even tackle a few biochemistry topics including carbohydrates, amino acids, lipids and more.

You’ll spend anywhere from a day to two weeks on a given class of reactions, and then you’ll move on.

You’ll be expected to remember the beginner reactions, as they will tie into the steps of the more advanced reactions.

That’s it!

What Can I Do To Ace the Class?

So now that you know what to expect, how the heck do you prepare for a class like this?

The first thing to recognize is that while it may seem overwhelming to learn 50 to 200 reactions, it’s really not that difficult!

How do you do it? By recognizing patterns and similarities.

For example, when you start on alkene reactions, you’ll learn the following mechanisms:

Halogenation
- Bromination
- chlorination
Hydrohalogenation
- Hydrobromination
- hydrochlorination
Acid catalyzed hydration
- And an alcohol for good measure
Halohydrin formation
- Bromohydrin
- chlorohydrin

That’s 7 reactions there alone, right? Not really!

If you identify the principles of the reaction,
the what and why for each step of the attack,
you’re really learning ONE reaction: alkene nucleophile attacking an electrophile.

So as you study, ask yourself this question over and over:

“What are the similarities, what are the patterns, and even more importantly, why does this happen?”

By learning to think in this critical manner from Day 1, your studies will become immensely easier.

Don’t get me wrong: this class is still tough.

You’ll be required to invest many hours each week studying;

I recommend a MINIMUM of 10 hours per week for the average student.

But you won’t be wasting time trying to figure out what the heck is going on,
and you certainly won’t be trying to cram new information the night before your exam.

You will understand and practice reactions over and over and over.

Other tips

(as found in my 10 Secrets to Acing Organic Chemistry)

I recommend pre-learning the chapter at least an hour before class – or at least getting a quick exposure.
Read the chapter or watch related YouTube or Study Hall videos.
Spend another hour after class reviewing the material itself.

That’s 4 to 6 hours a week, depending on the number of classes per week (2 to 3 is normal).

The remaining time is for practice, practice, practice.

When you think you’ve done enough questions because you get it,
this is when you should do EVEN MORE practice questions.

That is the perfect time to test yourself even further to ensure you can confidently answer a problem no matter the twist, trick, or format presented.

For a headstart on the logic, I recommend watching video one in the Alkene Reaction Series. This video will explain the idea behind the big players in organic chemistry: mechanisms, nucleophile and electrophile.

What about you?
What about your organic chemistry course concerns you most?
Let me know in the comments below.

Cyclohexane Chair to Double Newman Quiz Challenge Question

October 26, 2016 By Leah4sci 2 Comments

This video walks you through the Chair Conformations Practice Quiz bonus question B – Converting a cyclohexane chair conformation to double Newman Projections.

Practice is ESSENTIAL to mastering Organic Chemistry. You have to be able to apply the skills you are learning. First, complete the Cyclohexane Chair Conformations Practice Quiz, and then watch this video where I go over the Challenge Question part B solution and explanation step-by-step!

(Watch on YouTube: Chair to Newman. Click cc on the bottom right to view video transcription.)

Links & Resources Mentioned In This Video

Watch the Newman Projections Tutorial Series
Try the Chair Conformation Practice Quiz!

<– Watch Previous Video: Cyclohexane Chair Conformations Axial and Equatorial Stability
–> Watch Next Video: Cyclohexane Ring Flip and Boat Conformation

Drawing Chair Conformations & Ring Flips step-by-step Written Tutorial

This is video 2 in the Chair Conformations Tutorial Series.

Would a Model Kit help you? Watch How to Use Your Organic Chemistry Model Kit.

Carbocation Stability and Ranking

October 19, 2016 By Leah4sci 2 Comments

Carbocations arise so frequently in Organic Chemistry that recognizing them must become second nature.

After reading this tutorial, you should be able to eyeball a molecule and determine where a carbocation is likely to form as well as its potential stability.

This will help you master carbocation intermediate reactions down the line including Markovnikov alkene addition reactions, unimolecular substitution SN1, beta elimination E1, and so much more.

What makes a carbocation and what determines whether or not it will be stable?

Let’s start with the basics.

I frequently see this written as CARBONcation. But it’s CARBOcation.

Carbocation can be broken down as follows:
carbo for carbon
Cat = positive
Ion = atom or molecule that gained/lost electron and now has a charge
Carbocation = positive carbon atom

Think of carbocation as having the + charge in the name:

Hybridization

Carbocations are sp2 hybridized with an empty ‘p’ orbital sitting perpendicular to the molecule.

This is EXTREMELY important in understanding the stereochemistry of reactions.

Carbocations form when carbon loses an electron in the form of a bond or electron pair.

Think of a leaving group departing and taking along its electrons:

Think of an alkene attacking, removing its pi electrons from one of the carbon atoms:

The carbocation is left with 3 sigma bonds only. These are made from the hybridization of s + p + p.

Recall from your molecular geometry that sp2 hybrids are 120 degrees and trigonal planar or ‘flat’.

A quick formal charge calculation (using this shortcut) gives us 4 – 3 = + 1

Positive Charge is a Lack of Something

When looking at the movement of electrons or positive charges, it’s easy to imagine the positive charge as a physical thing that can move from atom to atom.

This is true for negative, but NOT positive charge.

Think back to the day before your last crazy exam.
You hopefully sat there all day studying and working on practice questions…
Are you like me where you get ‘in the zone’ and forget to eat?
You sit there, studying as your stomach grumbles away.

Let’s ignore physiology for this example and simply think of the feeling of hunger!
You’re hungry,
You feel it in the pit of your stomach.
Does it feel like there is something physical in your stomach?
Or is that feeling of hunger better described as the feeling of loss?

Hunger is the feeling of a LACK of something,

(food being the something).

Now imagine your friend says,
“You’ve been studying so hard all day. I’m taking you to your favorite all-you-can-eat buffet.”
Buffets are dangerous for me. I love food.
And when I’m full I regret that I can’t eat more!
But I still try…

So you pull a Leah and eat, and eat, and eat, till you feel ready to burst.
Is that feeling of fullness just a feeling, or is it the physical food pushing on the walls of your stomach as your intestines try to keep up and help with digestion?
Yup, it’s something physical.
Food is physically pushing on the walls of your stomach.

But what the heck does this have to do with carbocation stability?

Think of carbon as a hungry atom.

It likes to have the right amount of food – a full octet with a formal charge of zero.

When carbon has too many electrons and gains a formal charge of negative one, that negativity is the measurement of something physical.

The extra food or electrons represent a physical something. These ‘electron’ somethings result in that negative charge.

4 – 5 = -1

On the other hand, the carbocation is a hungry carbon atom.

It’s empty stomach or ‘p’ orbital feels the hunger or positive charge as the feeling of a lack of something.

Since the positive charge isn’t something physical, it is unable to move.

This means that you CANNOT draw an arrow from the positive charge to show it moving to another atom:

Instead, a nearby atom can give ITS OWN FOOD or electrons to carbon via a carbocation rearrangement, filling up that empty ‘p’ orbital of the carbocation.

After giving it’s electron up, the nearby atom will now feel hungry and feel its own hunger as a carbocation!

Unless the nearby atom had extra electrons (food) and is sharing with carbon.

Carbocation Stability

When you hear the term ‘carbocation stability,’ do you automatically assume that carbocations are stable? If so, then that’s opposite from the truth.

Carbon atoms do not like having a positive charge!

Some endure begrudgingly as we’re about to see. But do not think just because they CAN that they enjoy doing so.

Both positive and negative charges are considered a burden and atoms will execute fierce battles and attacks to get rid of this burden.

Remember, when it comes to organic chemistry and science/life in general:

happy, stable, unreactive…

Wait, what?

So what’s carbocation stability?

Stability isn’t a question of yes or no. But rather WHICH carbocation is more stable and therefore, more likely to form compared to less stable, and less likely form.

Your textbook, and professor, likely taught you something like this:

As you can see from the trend, more substituted carbocations are more stable.

Review the pencil trick if you can’t quickly identify primary/secondary/tertiary carbon atoms.

BUT DON’T JUST MEMORIZE THIS!!

WHY are the more substituted carbocations more stable?

Once again, when trying to understand a difficult orgo concept, let’s give it some human characteristics!

The Technical Definition

Carbocations are stabilized by neighboring groups due to hyperconjugation.

Hyperconjugation is the result of a sigma bond overlapping ever so slightly with a nearby ‘p’ orbital. In our case, the empty ‘p’ orbital of the carbocation. Without actually donating electrons it manages to provide some increased electron density to stabilize the empty ‘p’ orbital.

SAY WHAT?

Once you memorized the word and definition, let’s step away from the concepts that make no sense.

Nearby carbon groups provide moral support to the carbocation.

Alkyl Group = Moral Support

Imagine your orgo professor decides to give you a 30-question homework assignment, the night before your exam… that is DUE on the day of your exam under the guise of helping you prepare.

You’re mad! You’re fuming! You can’t believe your bad luck.
You’re so upset. You’re now carrying this burden of anger.
But, you chose to study in your dorm and your roommate is out with friends.
You’re all alone and have no one to vent to!

You’re stuck carrying that burden with zero support and that makes you VERY, VERY angry or unstable.
Now imagine, your roommate returns for the evening and allows you to have a really good vent!
You’re still carrying that burden but, perhaps you feel ever so slightly better?
Not too much better.
Your roommate understands and quickly texts your friends.
One of them shows up right away and you vent all over again.
Now you feel a bit better that you are able to vent to two people.

While you’re still carrying that burden, it suddenly doesn’t feel AS bad. You have moral support on either side and you start to believe that, perhaps, you can do this!

Then your other friend shows up and you vent again…
Now you have THREE people to vent to!
You’re surrounded by moral support.

You still have the burden. But you know what?
They remind you that it’s not so bad. And 30 extra practice problems means you’ll be so much more prepared for that exam.

You can finally sit down and tackle the questions.

But, what’s this about a partial orbital overlap?

Assuming you’re the huggy type (I love hugs), the overlap represents your friend, reaching over and giving you a supportive hug.
Two friends = 2 hugs
3 friends = surrounded by supportive hugs

That’s how carbon feels.

A methyl carbocation is all alone. It’s carrying a burden it feels is too heavy with no moral support whatsoever.

It’s very unstable and for the most part will NOT form under typical conditions in organic chemistry.

Moral Support and Ranking Carbocation Stability

Primary Carbocation

The primary carbocation is not stable. It only has one friend nearby for limited moral support.
The alkyl group friend, reaches over with an orbital hug, but it’s not enough to stabilize the burden on the primary carbocation.

You WILL NOT see a primary carbocation forming under standard conditions.

Avoid the primary carbocation like the plague in your Alkene and SN1/E1 reactions.
These CAN form under extreme conditions first seen in late orgo 1 or early orgo 2 in EAS – Friedel Crafts Alkylation

Secondary Carbocation

The secondary carbocation has two friends providing moral support.

The carbon atom feels a bit more stable and relaxed and is getting the ‘orbital hug’ (hyperconjugation) from both sides.

It’s not very stable, but it can form under the right conditions.
You’ll see these forming slowly in your Alkene reactions and more.

Tertiary Carbocation

This is where we start to enter the realm of ‘stable’ carbocations.

The deficient carbon atom has 3 nearby alkyl groups completely surrounding it with orbital hugs for moral support in the form of hyperconjugation.

This is the fastest carbocation to form when there is no nearby resonance and will result in faster reactions in alkenes, substitution, elimination and more.

For more on Ranking, check out this Pencil Trick Tutorial and Video

Resonance Stabilized Carbocations

Moral support and hugs will only take you so far. They can empower you to deal with your burden, but at the end of the day, you’re still stuck with that burden.

Back to the surprise homework night before the exam…

Now imagine that instead of just ‘friends’ coming over to support you and hear you vent, your classmate comes over so that the two of you can work through the problems together!
Perhaps your classmate is better at orgo than you.
Awesome!
Perhaps your classmate isn’t as proficient.
But, as long as both of you are dedicated to working out the problems, can you see how the actual help will instantly lessen the burden?

The point is, now you’re carrying LESS THAN 100{4de72ea05502f43f582be05109791d04c2e06ba4d55e604218cbe1ea315cd788} of the initial burden, it may not be a 50/50 split but you’re still required to carry less of that overall burden.

That’s how I envision resonance.

Alkyl groups will stabilize a carbocation, but will NOT help lessen the actual physical burden.

Resonance structures allow the charge to be shared among two or more atoms allowing each individual atom to carry a smaller portion of the overall burden.

Allylic Carbocation

An allylic carbon is one that is directly attached to a pi bond.

An allylic system has a minimum of 3 carbons. The allylic carbon and the nearby double bond.

Vinyl Carbocation

DO NOT confuse an allylic group with a vinyl group.

A vinyl carbocation has a positive charge ON THE SAME carbon as the double bond. This is VERY, VERY, unstable and ranks under a methyl carbocation in stability.

Allylic carbocations are able to share their burden of charge with a nearby group through resonance.

A simple allylic system will have just one pi bond

Though you may see multiple resonating pi bonds

When resonating, the burden of charge is shared between 2 (or more) carbon atoms just like the homework assignment being worked on by two students.

This concept requires a solid understanding of resonance.

Rusty? Review the Resonance tutorial series

Just as with alkyl carbocations, nearby groups will still help stabilize the charge.

This means that a primary allylic carbocation, while stable, is still less stable compared to a secondary which is less stable when compared to a tertiary allylic pi bond.

I challenge you to draw out resonance for the systems below and verify the substitution on the yellow highlighted carbon atom.

Don’t forget to rank both the initial carbocation and the stability of the atom that accepts the carbocation.

Any level of help will lessen the burden,

but the more substituted the pi bond, the more likely to have resonance.

Comparing Allylic and Aliphatic Resonance

Having help is typically better than moral support, unless that support is REALLY, REALLY strong.

Primary allylic carbocations typically rank at the same stability as a secondary carbocation.

A secondary allylic carbocation will be more stable than an aliphatic secondary allylic because it has the same moral support AND resonance.

Tertiary allylic will be even more stable.

Benzylic Carbocation

The benzylic carbocation is NOT a positive charge on benzene itself. Instead, it’s a carbocation sitting at the benzylic carbon –> the carbon directly attached to the benzene ring.

If the carbocation is you with a homework assignment, the benzene ring is your entire study group teaming up to complete the work together.

Imagine how much better you’ll do when working with 3 other motivated classmates.
Everyone contributes approximately 25{4de72ea05502f43f582be05109791d04c2e06ba4d55e604218cbe1ea315cd788} of the effort and your assignment is complete.

Benzylic carbocations are so stable because they have not one, not two, but a total of 4 resonance structures.

(review Benzene resonance in this video)

This shares the burden of charge over 4 different atoms, making it the MOST stable carbocation.

Some professors will rank a primary benzylic carbocation under or near a tertiary carbocation.

As you increase substitution, the benzylic carbocation becomes more and more stable. The most stable version is the tertiary benzylic carbocation.

Remember when we said that stability isn’t a question of yes or no. But rather, WHICH?
Which carbocation is more stable, and therefore, more likely to form compared to a less stable form?

The points above should have aided in your fundamental understanding of this concept. And once you understand WHY a certain carbocation is more stable than the other, you’ll be able to quickly determine which one forms faster, or if they form at all!

Now, what happens if you have a carbocation near a carbon atom with potential to form an even more stable carbocation?

This is where we get into carbocation rearrangements, including hydride and methyl shifts, and even ring expansions. These concepts are covered in the videos below.

What do you think? I’d love to read your feedback in the comments below.

Cyclohexane Chair Conformations Axial and Equatorial Stability

October 3, 2016 By Leah4sci 2 Comments

“Why does cyclohexane have to be in a chair conformation? How do I know which carbon goes up or down?”

Learn this and more in video 1 of the chair conformation series. Learn how to recognize a chair, what it represents (with a model kit and on paper) and the nature of axial and equatorial substituents.

(Watch on YouTube: Chair Conformations. Click cc on the bottom right to view video transcription.)

Links & Resources Mentioned In This Video

Get your own Organic Chemistry Model Kit
Try the Chair Conformation Practice Quiz

–> Watch Next Video: Cyclohexane Chair to Double Newman Quiz Challenge Question

Check out the Drawing Chair Conformations & Ring Flips step-by-step Written Tutorial

This is video 1 in the Chair Conformations Tutorial Series.

After you’ve been through the tutorial, don’t forget to test your understanding with the Chair Conformations Quiz!

Would a Model Kit help you? Watch How to Use Your Organic Chemistry Model Kit.

Resonance Structures Organic Chemistry Tutorial Video

September 26, 2016 By Leah4sci Leave a Comment

Orgo Basics Video Series: Video 6
Resonance structures are alternative Lewis structures for a molecule or an ion. To draw the resonance hybrid or structures, we are moving electrons between adjacent atoms. Overwhelmed?

In the video below, you will see an explanation and illustration of resonance structures and resonance hybrids step-by-step. This will help you visualize what is going on behind arrows.

(Watch on YouTube: Resonance. Click cc on bottom right for video transcription.)

Links & Resources Mentioned In This Video:

For an even more in-depth review of resonance, see the Resonance Video Series
and try then try the Resonance Practice Quiz

<– Watch Previous Video: Lewis Structure Organic Chemistry Tutorial
–> Watch Next Video: Major and Minor Resonance Contributing Structures

This is Video 6 in the Orgo Basics Video Series. Click HERE to view the entire series.

Major and Minor Resonance Contributing Structures

September 26, 2016 By Leah4sci Leave a Comment

Orgo Basics Video Series: Video 7
You know now how to draw the resonance structures. But which one is the most accurate resonance structure? Which one is most representative of the molecule?

In this video, I will explain what it means to be the most stable & least stable resonance structures and how to identify it among all the contributing structures.

(Watch on YouTube: Major/Minor. Click cc on bottom right for video transcription.)

Links & Resources Mentioned In This Video:

For an even more in-depth review of resonance, see the Resonance Video Series
and try then try the Resonance Practice Quiz

<– Watch Previous Video: Resonance Structures Organic Chemistry Tutorial

This is Video 7 in the Orgo Basics Video Series. Click HERE to view the entire series.

Cis Trans and E Z Geometric Isomers

September 18, 2016 By Leah4sci Leave a Comment

Your organic chemistry course will cover many different types of isomers.

Isomers have the same molecular formula but something about them is different.
Geometric isomers, a type of stereoisomer, differ in their geometry or shape. This happens when substituents are LOCKED in a specific relationship to each other.

I say locked because, unlike conformational isomers in Newman Projections, you can’t simply rotate the molecule to change the relationship between substituents.

In this tutorial, we’ll look at alkene geometric isomers including cis trans and E Z.

Cis/Trans Isomerism

Cis/Trans isomerism is typically seen with substituents on either side of the alkene double bond.

How does this happen?

Alkene double bonds occur between sp2 hybridized carbon atoms. Recall: sp2 hybrids have a trigonal-planar or ‘flat’ geometry.

(Not comfortable with this? Review sp2 Hybridization.)

But it’s not the hybrid we’re looking at.

Instead, it’s the un-hybridized p-orbital that forms a SECOND bond between the 2 carbon atoms.

An sp3 hybridized single or simga bond is free to rotate.

Sp2 pi bonds are locked in place.

The only way to rotate this bond is to break the double bond, rotate, and reform the double bond –which is typically not observed.

In fact, this requires high energy, as you’ll see in your Diels Alder reactions later on.

Take a look at the following generic alkene and it’s 4 substituents:

Carbon 1 has substituents A and B; Carbon 2 has substituents C and D.

But notice specifically how A is on the same side as C, and B is on the same side as D.

The only way to bring A next to D is to break the pi bond, rotate the molecule, and reform the pi bond. Otherwise A is locked in place near C, and B is locked in place near D.

Cis vs Trans Alkenes

Let’s take a look at 2 versions of 2-butene: 2-butene is a 4-carbon chain with a double bond between carbons 2 and 3.

So, we can draw this incorrectly, as a linear molecule:

Or, draw each sp2 carbon at a 120 degree bond angle. This gives me the option of placing both methyl groups up, down, or one up and one down.

The first two are actually the same: both cis. You see, I can flip the molecule and make the first superimpose (overlap) the second without breaking any bonds.

The third is unique. The only way to superimpose the third is to break the double bond.

Cis Alkenes

I like to think of cis as ‘sisters’. They are together on the same side.
Cis alkenes have substituents on the same side of the double bond.

Trans Alkenes

I like to think of trans substituents as having ‘transferred away from each other.’ Putting them on opposite sides.
Trans alkenes have their substituents on opposite sides.

Naming Cis/Trans Alkenes:

Once you’ve identified cis/trans alkenes, naming them is fairly simple.

1) First, name the alkene using the tutorial linked below.

2) Then, simply add ‘cis’ or ‘trans’ in front of the name.

Take the 2 geometric isomers of 2-butene:

Their proper names are as follows:

When there is only one pi bond, you don’t have to specify which carbon is cis or trans since. It’s self-understood.

When you have more than one double bond on the molecule, you must specify which is cis and which is trans.

Take this molecule for example: 2,5-octadiene

This molecule has 2 pi bonds. One cis and one trans.

Since there is more than one pi bond, you have to specify which pi bond is cis and which is trans.

Alkene stability

Not all isomers have the same stability.

It’s all about stability – in organic chemistry or science in general.

Trans alkenes are MORE STABLE than their cis counterparts.

This is more apparent with larger substituents.

Trans Alkenes

In a trans alkene, the substituents are facing away from each other.
They don’t ‘get in each other’s faces’ and therefore, don’t mind the other groups.

Cis Alkenes

Cis alkene substituents are close together and will ‘get in each others faces.’ This causes ‘arguments’ when one group invades the other’s personal space.

When the groups try to move away from each other, they cause strain on the molecule.

All of this leads to an unhappy and higher energy cis conformation.

Cis & Trans on Cyclic Compounds

Ring structures or cyclic compounds can also exhibit cis/trans isomerism without the presence of a pi bond.

Remember, substituents will be cis and trans if they are locked in place. Pi bonds are one way to lock them in place. Rings are another matter.

For example, in 1,2-dimethylcyclohexane, I can show both substituents going into the page or both going out of the page.

Since they’re pointing in the same direction, they are cis to each other.

If I show one going into the page and one going out of the page. They are trans to each other.

Even though the carbons are sp3 and sigma bound to each other, the molecule itself cannot rotate because of the ring structure. Locked.

The only way to turn cis-1,2-dimethylcyclohexane into trans-1,2-dimethylcyclohexane, is to break open the ring, rotate, and reform the ring.

What if there’s more than one substituent on the sp2 carbon?

Till now, we’ve looked at molecules with just one substituent on either side of the sp2 pi bound carbon.

What happens if we have a pi bond with 2 different atoms or groups on the sp2 carbon?

Take a look at 3-methyl-2-pentene:

Here in line structure:

You can draw this molecule in 2 different ways. But will you compare the red methyl or red ethyl to the green methyl when choosing cis or trans?

3-methyl-2-pentene cis or trans

While some professors WILL teach you to compare the larger groups, the answer is that you CANNOT compare simply choose one for cis and trans.

Introducing the E Z Notation

When a pi bond has more than one substituent on each side, or contains non-carbon substituents, we’ll need a more advanced system for identifying geometric isomerism.

The E Z system requires ranking the groups on either side of the pi bond. We must determine if the higher priority groups are next to each other, Z (think cis), or away from each other, E (think trans).

But first, we have to learn how to rank groups using the Cahn-Ingold-Prelog notation.

The video below is from my chirality series, but teaches this concept in detail. Start watching from 0:52

Cahn-Ingold-Prelog in summary:

We’re ranking atoms based on their atomic number.
Not mass of the group, not size of the group.

The higher the atomic number of the atom directly attached, the higher the priority.

Here are the 10 most common atoms you’ll come across from high to low priority:
I > Br > Cl > S > P > F > O > N > C > H

Here’s My Simple Approach

Highlight your double bond, then look at just one half of the molecule at a time. Use your hand or another paper to cover the other half of the molecule.
Determine which group is higher priority and put a number 1.
I like to draw an arrow perpendicular to the pi bond so I can clearly see if it’s up or down by comparison.
Do the same thing for the other side.

E is for Eeposite, Z is for Ze Zame Zide

If the two high priority groups are opposite to each other, think of them as being ‘eeposite’ to each other.

E is for Eeposite.

If the two high priority groups are on the the same side, or should I say on ‘Ze Zame Zide,’ they are Z.

This applies to molecules that have more than just 1 carbon on either side of double bond.

Ze Zame Zide.

Let’s go back to the example above:

On the left, OH outranks ethyl since oxygen has a higher atomic number when compared to carbon. OH is #1 and points down.

On the right, Cl outranks methyl since chlorine has a higher atomic number when compared to carbon. Cl is #1 and points down.

Since both arrows point in the same direction (down), we conclude that the priority groups are on Ze Zame Zide making it Z.

2 Equal Priority Groups

Sometimes you’ll see a trick question where an sp2 carbon will have 2 of the exact same groups.

Since you cannot rank one over the other, there will be NO cis/trans or E/Z isomerism.

Here are 2 common examples:

1) A terminal pi bond

Carbon #1 in 1-butene has 2 hydrogen atoms.
Since H vs H have the same exact priority, this molecule will have no cis/trans or E/Z isomerism.

2) Same exact groups on the same sp2 pi bound carbon.

Carbon #2 in 2-methyl-2-butene has 2 CH3 groups.

One appears to be part of the parent chain, the second appears to be a methyl substituent.
However, when CH3 is compared to CH3 they rank exactly the same.

This molecule will have no cis/trans n/or E/Z isomerism.

Cis and Trans vs E and Z

If we go back to our cis/trans practice problems, such as cis and trans 2-butene, you’ll see that we can use the E/Z system here as well.

Carbon 2 and 3 each have a methyl group outranking a hydrogen atom. When they are cis, you get Z. When they are trans you get E.

A word of caution

You CAN use E/Z for cis/trans isomers, but you cannot use cis/trans for complex E/Z isomers as we’ve already shown above.

In Summary

Cis vs trans and E vs Z isomers are geometric isomers that occur when substituents are locked in position next to or opposite each other. This is seen in both double bonds for alkenes, and substituents on ring structures.

Cis alkenes are on the same size, trans alkenes are on opposite sides. When the substituents are more complicated use the more advanced E/Z notation after determining the relationship of high priority groups.

Complete Guide to Recognizing, Drawing, and Naming Functional Groups in Organic Chemistry

The R Group

Alkyl Halide Substituent -X

Naming Alkyl Halides

The Nitro Functional Group -NO2

Naming Nitro Groups

Thioether Functional Group -SR

Naming Thioethers

Ether Functional Group -OR

Naming Ethers

Amine Functional Group -NH2 -NHR -NR2 -NR3+

Naming Amines

Thiol Functional Group -SH

Naming Thiols

Alcohol Functional Group -OH

Naming Alcohols

The Carbonyl Group

Ketone Functional Group -COR

Drawing Ketones

Naming Ketones

Aldehyde Functional Group -CHO

Drawing Aldehydes

Naming Aldehydes

Nitrile Functional Group -CN

Naming Nitriles or Cyano Groups

Carboxylic Acid Derivatives

Amide Functional Group -CONH2 -CONRH -CONR2

Drawing Amides

Naming Amides

The Acid Halide Functional Group -COX

Drawing Acid Halides

Naming Acid Halides

Ester Functional Group -COOR

Naming Esters

Acid Anhydride Functional Group

Naming Anhydrides

Carboxylic Acid Functional Group -COOH

Naming Carboxylic Acids

What do you think?

Links & Resources Mentioned In This Video:

This is Video X in the Orgo Basics Video Series. Click HERE to view the entire series.

Links & Resources Mentioned In This Video

This is video 3 in the Chair Conformations Tutorial Series.

The first step to conquering an unknown beast is understanding it.

How Organic Chemistry Differs From The Other Sciences

Enter Organic Chemistry.

How to Succeed in Organic Chemistry

So what will you actually cover in Organic Chemistry?

The first week or two is more of a general chemistry review than organic chemistry.

Resonance

It’s not just about what’s connected to what, it’s also about how.

Mechanisms

How the heck are there enough reactions to fill two full semesters? What do you even cover in Orgo 2?

What Can I Do To Ace the Class?

How do you do it? By recognizing patterns and similarities.

By learning to think in this critical manner from Day 1, your studies will become immensely easier.

Other tips

What about you? What about your organic chemistry course concerns you most? Let me know in the comments below.

Links & Resources Mentioned In This Video

This is video 2 in the Chair Conformations Tutorial Series.

What makes a carbocation and what determines whether or not it will be stable?

Hybridization

The carbocation is left with 3 sigma bonds only. These are made from the hybridization of s + p + p.

Positive Charge is a Lack of Something

Hunger is the feeling of a LACK of something,

Think of carbon as a hungry atom.

On the other hand, the carbocation is a hungry carbon atom.

Carbocation Stability

Both positive and negative charges are considered a burden and atoms will execute fierce battles and attacks to get rid of this burden.

The Technical Definition

Once you memorized the word and definition, let’s step away from the concepts that make no sense.

Alkyl Group = Moral Support

But, what’s this about a partial orbital overlap?

That’s how carbon feels.

Moral Support and Ranking Carbocation Stability

Primary Carbocation

Secondary Carbocation

Tertiary Carbocation

Resonance Stabilized Carbocations

The point is, now you’re carrying LESS THAN 100{4de72ea05502f43f582be05109791d04c2e06ba4d55e604218cbe1ea315cd788} of the initial burden, it may not be a 50/50 split but you’re still required to carry less of that overall burden.

What about you?
What about your organic chemistry course concerns you most?
Let me know in the comments below.