Organic Chemistry and the New MCAT

Organic Chemistry and the MCAT, by Leah Fisch

Note from James: This is a guest post by Leah Fisch of Leah4Sci.com , an online resource for learning organic chemistry, MCAT preparation, and other science topics . This is a comprehensive Leah wrote on organic chemistry and the MCAT. You might want to bookmark this page for future reference, and be sure to visit Leah’s Youtube Channel for more videos on nomenclature as well as other organic chemistry topics. Leah also tutors MCAT and organic chemistry. Her tutoring page is here. 

Finally: If you’re planning on taking the MCAT soon, you should download Leah’s free 6-Weeks To MCAT Prep Guide.

Exactly how much organic chemistry is on the MCAT?

As a premed student, organic chemistry is likely one of the most difficult sciences you’ve encountered. Why take such a difficult course? Because you need it for the MCAT!

However, in 2015, when the MCAT exam changed, the amount of organic chemistry appeared to decrease, making students wonder just how much time they should dedicate to the topic.

Implication: “is it even worth it?”

The answer is tricky. So instead of telling you how much to study… let’s break it down.

The MCAT has a total of 4 sections covering 8 disciplines:

• Physics
• General Chemistry
• Organic Chemistry
• Biochemistry
• Biology
• Psychology
• Sociology
• Verbal Reasoning (CARS)

Organic chemistry is just ONE of the eight subjects you have to study.

But it gets better:  orgo shows up in just the first and third section of the 7.5 hour exam.

Section 1: Chemical and Physical Foundations of Biological Systems is just 15% organic chemistry with the other 85% comprised of general chemistry, biochemistry, physics and biology.

Section 3: Biological and Biochemical Foundations of Living Systems is just 5% organic chemistry with the other 95% comprised of general chemistry, biochemistry and biology.

After a quick calculation organic chemistry appears to be just 5% of the entire exam!

But… don’t let the 5% estimate give you a false sense of security.

Biology is the most highly tested topic, but when you run the math it makes up just 18.75% of the MCAT.

Sounds low?

The math is somewhat misleading.

First of all, when medical schools evaluate your application, they look at more than just your total score. They look to see how you scored in each section, making organic chemistry suddenly more valuable. Consequently, even though it’s a small part of just two sections on the MCAT, skipping orgo study will tank your score in these sections, making you look bad.

The most important thing to recognize is just HOW organic chemistry is tested.

Fifteen percent of the first section doesn’t mean that 8.85 of 59 questions will be isolated organic chemistry questions.

Instead, the new MCAT is an integrated exam where you’ll be faced with research- and experiment-style passages combining multiple disciplines into a single passage and question: 

• While you may not be asked for an R/S question directly, you may be asked about the optical purity of a newly synthesized experimental drug.
• You may not be tested on aldol condensations directly, but you may face a question asking you how glycolysis will be impacted by a single amino acid mutation in the active site of aldolase, which is the enzyme that catalyzes an aldol-style reaction in glycolysis.

Understanding Concepts is MUCH MORE Important than Memorization! 

Your orgo professor likely asked FOR reactions, mechanisms, products, and lots of pushing arrows.

The MCAT is all multiple choice questions and applied concepts.

As you review reactions, don’t worry about memorizing mechanisms.

Instead, make sure to ask yourself these questions every step of the way.

• What is the purpose of this reaction?
• What is the purpose of this mechanism?
• What do I absolutely have to recognize about the reactant and reagent to help me understand the product? Focus on getting the logic, understanding the patterns and understanding what’s going on.

For example, Grignards are VERY reactive. They’ll attack all sorts of carbonyls. Don’t worry about which specific pair of electrons attack. Instead make sure you recognize the resulting alcohol product.

Why can’t you dissolve a Grignard in water or ethanol? Why should you complete the reaction with an acid workup AFTER the Grignard reacted? What happens if you mix the aqueous acid with the Grignard at the start of the reaction?

And most importantly, can you recognize the specific functional groups of this reaction when presented in the context of a biological or chemical research experiment?

As an MCAT tutor I’ve been interviewing students after each exam to understand the true nature of questions that arise on the exam.

This is where it gets interesting.

Once again, looking at just 15% orgo on the first section I notice an AVERAGE of 15% orgo questions. That is an average over the course of many exams combined.

One exam may have just two to three orgo questions about functional groups, S_N1 reactions or IR spec, while another exam will have as many as 15 organic chemistry questions.

Another thing I’ve noticed is that while you may have learned a certain topic in your organic chemistry course, the MCAT will find a way to test it under the disguise of biology or biochemistry. This is especially true with amino acid characteristics, separation techniques and of course chirality.

This makes the value of your organic chemistry study much more significant, as orgo success will be success in the other subjects as well.

What does this mean for you as a premed student?

“What about high yield topics?”

Students looking for shortcuts often want to know which high-yield orgo topics to study.

In other words: “if I just have time to cover a bit of orgo, which topics should I focus on?”

This is a trick question.

I’ve heard from MCAT testers that any given MCAT has covered multiple passages on a single “low-yield” topic. Students who’ve studied everything will get these correct. Students who followed their MCAT book’s advice on high-yield topics ONLY wound up missing out on quite a few simple (low yield) questions.

For example, one of the 2016 MCATs had no less than FIVE passages related to lab separation techniques. If you thought, “sure I’ll cover electrophoresis quickly” and didn’t study it well enough, you would have missed out on several questions.

With all of this in mind, make sure you absolutely master the following starting with all of the beginner orgo topics typically covered in first semester organic chemistry. Then focus on understanding the patterns and functional groups of reactions covered in orgo 2.

Why? Because organic chemistry 2 is simply orgo 1 on steroids building on these very foundations.

Here’s my recommendation for what to cover when studying organic chemistry for the MCAT

The following is not an exhaustive list but a very good start on what to focus on:

1. Start With The Basics

The AAMC considers some of these “general chemistry” topics but you likely covered this in organic chemistry 1.

• Lewis structure and bonding
• Hybridization, bond angles and electronic/molecular geometry [video]
• Structural formulas including skeletal structure (bond line notation) [video]

Nomenclature

Let’s face it, while you won’t be tested the nomenclature itself, you better know exactly what is meant by isopropyl, tert-butyl and more.

2. Isomers and Stereochemistry

• structural isomers (constitutional isomers) [video]
• conformational isomers including Newman and Chair
• Chirality including R/S, D/L, enantiomers, diastereomers, meso compounds and more
• cis/trans and E/Z
• Acids & Bases: The non-math (non gen chem) aspect (such as acidity trends)
• SN1/SN2/E1/E2 Reactions and how to differentiate between them

3. The following topics are sometimes covered in Org 1 or Org 2. Learn these well but don’t go too crazy!

• Alcohols & Phenols: Reactions, protecting groups, leaving groups
• Aromaticity: Concept more than reactions including heterocyclic aromatic compounds
• Aldehyde and Ketone: Direct Reactions, Reactions at the Alpha Carbon (enolates), Keto-Enol Tautomerism (KET) and more
• Amine reactions especially as they relate to amino acids
• Carboxylic Acids: Formation and Reactions
• Carboxylic Acid Derivatives, especially esters in biological molecules

4. The following topics are often introduced in orgo but covered in biochemistry

• Carbohydrates: orgo focus on Fischer Projections, stereochemistry and some reactions
• Amino Acids: orgo focus on Fischer Projections, stereochemistry and some reactions

5. And let’s not forget Lab Techniques

If the MCAT is all about experiments and research, make sure you know and truly understand the following analytical methods including simple graph interpretation:

• ¹³C and ¹H-NMR [video]
• IR (Infrared spectroscopy)
• UV (Ultraviolet spectroscopy)

Separation Techniques

• Extraction
• Distillation
• Chromatography

6. What about all those crazy orgo 2 reactions not listed above?

Don’t skip them completely just in case.

Don’t go nuts as you review but simply look at your book and try to understand what’s going on.

For example Acetoacetic Ester Synthesis, Michael Addition and more. These are SPECIFIC reactions that incorporate bits and pieces of the reactions listed above.

So while you’re not required to know this mechanism, acetoacetic ester synthesis is really just a combination of the following reactions:

• Acid base
• S_N2
• dehydration/elimination
• Keto Enol Tautomerization

I challenge you to go study the steps and verify that the above is true. 

The MCAT EXPECTS you to recognize that this is the case, but in reality most students are under too much pressure to make these connections.

To be safe, spend some time each day watching a short advanced reaction mechanism tutorial video or reviewing a single reaction in your orgo book. Let the book/tutorial make the connections for you so that your brain power is reserved for figuring out what the heck they are asking in the passage/question.

Let’s take this to the extreme.

Nowhere on the AAMC outline do you see the mention of alkenes.

Does this mean you can skip it? Not quite!

Let’s read between the lines:

• E1/E2 including alcohol dehydration = alkenes.
• What if you reverse the reaction? That’s an alkene addition reaction!
• What if you have to synthesize an alcohol? Alkenes make good starting points.
• What about Cis/Trans E/Z isomers as the product of a reaction?

Once again, alkene reactions.

And yes, MCAT testers HAVE confirmed seeing all of this on their MCAT.

What does this mean for you as a premed student?

Do NOT discount organic chemistry just because there’s so much else to study.

Instead I recommend breaking up your study schedule so that you devote time to cover a little bit of EACH MCAT topic on a weekly basis including organic chemistry.

So how do you structure your schedule in a manner that allows you to cover ALL of the content for the MCAT and work in practice questions and full lengths, without forgetting or burning out?

Download my free ‘6 Weeks to MCAT Prep Guide’ by visiting Leah4sci.com

Thanks for demystifying the recent changes to the MCAT Leah – and best wishes to everyone for a successful test! – J