MCAT Organic Chemistry Review: For MCAT 2015 (Graduate School Test Preparation) - P.J. Alaimo, Ph.D. 2015

Organic Chemistry Strategy for the MCAT

2.1 SCIENCE SECTIONS OVERVIEW

There are three science sections on the MCAT:

• Chemical and Physical Foundations of Biological Systems

• Biological and Biochemical Foundations of Living Systems

• Psychological, Social, and Biological Foundations of Behavior

The Chemical and Physical Foundations of Biological Systems section (Chem/Phys) is the third section on the test. It includes questions from General Chemistry (about 35%), Physics (about 25%), Organic Chemistry (about 15%), and Biochemistry (about 25%). Further, the questions often test chemical and physical concepts within a biological setting, for example, pressure and fluid flow in blood vessels. A solid grasp of math fundamentals is required (arithmetic, algebra, graphs, trigonometry, vectors, proportions, and logarithms), however there are no calculus-based questions.

The Biological and Biochemical Foundations of Living Systems section (Bio/Biochem) is the first section on the test. Approximately 65% of the questions in this section come from biology, approximately 25% come from biochemistry, and approximately 10% come from Organic and General Chemistry. Math calculations are generally not required on this section of the test, however a basic understanding of statistics as used in biological research is helpful.

The Psychological, Social, and Biological Foundations of Behavior section (Psych/Soc) is the fourth and final section on the test. About 60% of the questions will be drawn from Psychology, about 30% from Sociology, and about 10% from Biology. As with the Bio/Biochem section, calculations are generally not required, however a basic understanding of statistics as used in research is helpful.

Most of the questions in the science sections (about 75%) are passage-based, and each section will likely have about nine or ten passages. Passages consist of a few paragraphs of information and include equations, reactions, graphs, figures, tables, experiments, and data. Five to seven questions will be associated with each passage.

The remaining 25% of the questions in each science section are freestanding questions (FSQs). These questions appear in groups interspersed between the passages. Each group contains four to five questions.

95 minutes are allotted to each of the science sections. This breaks down to approximately one minute and 25 seconds per question.

2.2 GENERAL SCIENCE PASSAGE TYPES

The passages in the science sections fall into one of three main categories: Information and/or Situation Presentation, Experiment/Research Presentation, or Persuasive Reasoning.

Information and/or Situation Presentation

These passages either present straightforward scientific information or they describe a particular event or occurrence. Generally, questions associated with these passages test basic science facts or ask you to predict outcomes given new variables or new information. Here is an example of an Information/Situation Presentation passage:

Figure 1 shows a portion of the inner mechanism of a typical home smoke detector. It consists of a pair of capacitor plates which are charged by a 9-volt battery (not shown). The capacitor plates (electrodes) are connected to a sensor device, D; the resistor R denotes the internal resistance of the sensor. Normally, air acts as an insulator and no current would flow in the circuit shown. However, inside the smoke detector is a small sample of an artificially produced radioactive element, americium-241, which decays primarily by emitting alpha particles, with a half-life of approximately 430 years. The daughter nucleus of the decay has a half-life in excess of two million years and therefore poses virtually no biohazard.

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Figure 1 Smoke detector mechanism

The decay products (alpha particles and gamma rays) from the 241Am sample ionize air molecules between the plates and thus provide a conducting pathway which allows current to flow in the circuit shown in Figure 1. A steady-state current is quickly established and remains as long as the battery continues to maintain a 9-volt potential difference between its terminals. However, if smoke particles enter the space between the capacitor plates and thereby interrupt the flow, the current is reduced, and the sensor responds to this change by triggering the alarm. (Furthermore, as the battery starts to “die out,” the resulting drop in current is also detected to alert the homeowner to replace the battery.)

C = ɛ0 Image

Equation 1

where ɛ0 is the universal permittivity constant, equal to 8.85 × 10−12 C2/(N·m2). Since the area A of each capacitor plate in the smoke detector is 20 cm2 and the plates are separated by a distance d of 5 mm, the capacitance is 3.5 × 10−12 F = 3.5 pF.

Experiment/Research Presentation

These passages present the details of experiments and research procedures. They often include data tables and graphs. Generally, questions associated with these passages ask you to interpret data, draw conclusions, and make inferences. Here is an example of an Experiment/Research Presentation passage:

The development of sexual characteristics depends upon various factors, the most important of which are hormonal control, environmental stimuli, and the genetic makeup of the individual. The hormones that contribute to the development include the steroid hormones estrogen, progesterone, and testosterone, as well as the pituitary hormones FSH (follicle-stimulating hormone) and LH (luteinizing hormone).

To study the mechanism by which estrogen exerts its effects, a researcher performed the following experiments using cell culture assays.

Experiment 1:

Human embryonic placental mesenchyme (HEPM) cells were grown for 48 hours in Dulbecco’s Modified Eagle Medium (DMEM), with media change every 12 hours. Upon confluent growth, cells were exposed to a 10 mg per mL solution of green fluorescent-labeled estrogen for 1 hour. Cells were rinsed with DMEM and observed under confocal fluorescent microscopy.

Experiment 2:

HEPM cells were grown to confluence as in Experiment 1. Cells were exposed to Pesticide A for 1 hour, followed by the 10 mg/mL solution of labeled estrogen, rinsed as in Experiment 1, and observed under confocal fluorescent microscopy.

Experiment 3:

Experiment 1 was repeated with Chinese Hamster Ovary (CHO) cells instead of HEPM cells.

Experiment 4:

CHO cells injected with cytoplasmic extracts of HEPM cells were grown to confluence, exposed to the 10 mg/mL solution of labeled estrogen for 1 hour, and observed under confocal fluorescent microscopy.

The results of these experiments are given in Table 1.

Table 1 Detection of Estrogen (+ indicates presence of Estrogen)

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After observing the cells in each experiment, the researcher bathed the cells in a solution containing 10 mg per mL of a red fluorescent probe that binds specifically to the estrogen receptor only when its active site is occupied. After 1 hour, the cells were rinsed with DMEM and observed under confocal fluorescent microscopy. The results are presented in Table 2.

The researcher also repeated Experiment 2 using Pesticide B, an estrogen analog, instead of Pesticide A. Results from other researchers had shown that Pesticide B binds to the active site of the cytosolic estrogen receptor (with an affinity 10,000 times greater than that of estrogen) and causes increased transcription of mRNA.

Table 2 Observed Fluorescence and Estrogen Effects (G = green, R = red)

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Based on these results, the researcher determined that estrogen had no effect when not bound to a cytosolic, estrogen-specific receptor.

Persuasive Reasoning

These passages typically present a scientific phenomenon along with a hypothesis that explains the phenomenon, and may include counter-arguments as well. Questions associated with these passages ask you to evaluate the hypothesis or arguments. Persuasive Reasoning passages in the science sections of the MCAT tend to be less common than Information Presentation or Experiment-based passages. Here is an example of a Persuasive Reasoning passage:

Two theoretical chemists attempted to explain the observed trends of acidity by applying two interpretations of molecular orbital theory. Consider the pKa values of some common acids listed along with the conjugate base:

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Recall that acids with a pKa < 0 are called strong acids, and those with a pKa > 0 are called weak acids. The arguments of the chemists are given below.

Chemist #1:

“The acidity of a compound is proportional to the polarization of the H—X bond, where X is some nonmetal element. Complex acids, such as H2SO4, HClO4, and HNO3 are strong acids because the H—O bonding electrons are strongly drawn towards the oxygen. It is generally true that a covalent bond weakens as its polarization increases. Therefore, one can conclude that the strength of an acid is proportional to the number of electronegative atoms in that acid.”

Chemist #2:

“The acidity of a compound is proportional to the number of stable resonance structures of that acid’s conjugate base. H2SO4, HClO4, and HNO3 are all strong acids because their respective conjugate bases exhibit a high degree of resonance stabilization.”

2.3 GENERAL SCIENCE QUESTION TYPES

Question in the science sections are generally one of three main types: Memory, Explicit, or Implicit.

Memory Questions

These questions can be answered directly from prior knowledge, with no need to reference the passage or question text. Memory questions represent approximately 25 percent of the science questions on the MCAT. Usually, Memory questions are found as FSQs, but they can also be tucked into a passage. Here’s an example of a Memory question:

Which of the following acetylating conditions will convert diethylamine into an amide at the fastest rate?

A) Acetic acid / HCl

B) Acetic anhydride

C) Acetyl chloride

D) Ethyl acetate

Explicit Questions

Explicit questions can be answered primarily with information from the passage, along with prior knowledge. They may require data retrieval, graph analysis, or making a simple connection. Explicit questions make up approximately 35—40 percent of the science questions on the MCAT; here’s an example (taken from the sample Information/Situation Presentation passage):

The sensor device D shown in Figure 1 performs its function by acting as:

A) an ohmmeter.

B) a voltmeter.

C) a potentiometer.

D) an ammeter.

Implicit Questions

These questions require you to take information from the passage, combine it with your prior knowledge, apply it to a new situation, and come to some logical conclusion. They typically require more complex connections than do Explicit questions, and may also require data retrieval, graph analysis, etc. Implicit questions usually require a solid understanding of the passage information. They make up approximately 35—40 percent of the science questions on the MCAT; here’s an example (taken from the sample Experiment/Research Presentation passage):

If Experiment 2 were repeated, but this time exposing the cells first to Pesticide A and then to Pesticide B before exposing them to the green fluorescent-labeled estrogen and the red fluorescent probe, which of the following statements will most likely be true?

A) Pesticide A and Pesticide B bind to the same site on the estrogen receptor.

B) Estrogen effects would be observed.

C) Only green fluorescence would be observed.

D) Both green and red fluorescence would be observed.

2.4 ORGANIC CHEMISTRY ON THE MCAT

MCAT 2015 is likely to have around 9-10 passages and about 17 freestanding questions (FSQs) in each of the science sections. Organic chemistry is the least prevalent subject tested on the MCAT, and will make up roughly 15% of the Chemical and Physical Foundations of Biological Systems section and only about 5% of the questions on the Biological and Biochemical Foundations of Living Systems section. In the Chemical and Physical Foundations section of the test, the questions will be distributed between two to four freestanding questions and either one longer passage (with six or seven questions) or two very short passages (usually with four questions each). In the Biological and Biochemical Foundations section, the three or four O-Chem questions are likely to be either FSQs, or mixed in with either a biology or biochemistry passage. The O-Chem topics covered span roughly two college semesters’ worth of material but focus most on carbonyl chemistry and laboratory techniques. For now, let’s talk about what you can expect from O-Chem passages more generally, and we’ll get to specific content in the coming chapters.

2.5 TACKLING AN ORGANIC CHEMISTRY PASSAGE

In general, some sort of biologically important compound or reaction provides the context for O-Chem passages. The text of the passage might contain biologically related concepts or facts, but a sure sign that you’re reading an O-Chem passage and not a Biology passage will be chemical structures, usually lots of them.

Your approach to reading and mapping an O-Chem passage should be a bit different than your approach for all other subjects. The reason? There is hardly ever information within the text of an O-Chem passage that will be useful or needed to answer passage-based questions. The most important information in these passages will be in the form of chemical structures from synthetic or mechanistic schemes, or experimental data from a table, graph, or figure. Often, complicated syntheses and mechanisms can be intimidating because of all the detail presented, and they can slow you down considerably if you pay too much attention to this information during your first run through the passage. Be sure to read the titles of figures or schemes to get a sense of the big picture being presented, then jump into answering the questions quickly.

Passage Types as They Apply to Organic Chemistry

The main science passage types mentioned previously, when considered in the context of O-Chem, look something like this:

Information and/or Situation Presentation

These are the most common types of O-Chem passages, and generally present:

• A multistep synthetic scheme, a novel reaction, or atypical outcomes of reactions you might already be familiar with. Questions associated with these passages might ask you to analyze or classify the steps of the process described, or use common laboratory techniques to analyze intermediate compounds in the synthesis. You might need to justify the exceptions to the rules as described.

• A class of biologically important molecules. Questions associated with these passages could ask you to analyze the molecules with a common laboratory technique, or simply ask about their structure or their relationship to each other. You might also need to predict the reactivity of the molecules if treated with a given reagent.

• A biochemical process or mechanism. Questions here often test your understanding of the stability of intermediates and ask you to explain why the reaction occurs in the manner described. Given a new reactant, you might need to use the mechanistic steps to predict the product of a reaction.

Experiment/Research Presentation

This type of passage presents the details of an experiment or a mechanistic study, and often includes spectroscopy data (IR or NMR) in the form of lists or tables. Questions ask you to interpret data and identify the likely pathway of reaction. You might also need to identify compounds, or simply choose the appropriate technique to achieve the desired purification or product identification.

Persuasive Reasoning

This is the least common type of O-Chem passage, but can appear as a comparison of two mechanisms that attempt to explain the outcome of a reaction. Questions ask you to evaluate the arguments presented and will likely relate to the stability of intermediates.

Reading an O-Chem Passage

You should never really read much of the text of an O-Chem passage, but rather, just skim through the text. Remember that most of the important information you’ll use from an O-Chem passage will be in the form of the structures and data presented. O-Chem passage-based questions are often essentially freestanding questions. They require only reference to a structure given in the passage in order to answer. However, as you’re skimming the passage, you won’t know which structures, reaction steps, or data will be the useful bits, AND you won’t be able to mark or highlight structures in any way using your on-screen tools. That means that when skimming, you should get a general sense of the importance of each figure or table by reading titles and headings, but not get bogged down in the details of the figures in any way. You want to know where to go to examine the details when a question refers you to a particular synthetic step or structure along the pathway, something the MCAT is amazingly kind enough to do in most cases.

While you’re reading, be on the lookout for new italicized terms in the text to highlight, or unexpected outcomes of experiments and exceptions to rules. The MCAT will ask you to apply the science fundamentals you’ve studied to novel situations, so look for and highlight anything that might be out of the ordinary.

Mapping an O-Chem Passage

It will often be the case that the text of a passage will reproduce information presented in a more visually useful manner, such as a flowchart, reaction scheme, or mechanism. Try to focus on the structures, and resist the urge to make a lot of yellow marks in the text.

Since you cannot highlight any structures in the passage (this is unfortunate, since structures are the place you’ll get most of your necessary information), remember to use your scratch paper to make note of anything related to a reaction scheme or mechanism, especially if it’s taken you some time to come to your conclusion. Keep your scratch paper organized so it will be a useful tool if you need to refer to it while checking back over your answers toward the end of the section. Label each new passage with a number on your paper, and give it an identifying title that summarizes the main point of the passage.

If you reach an important conclusion while answering questions, be sure to make note of it on your scratch paper too. Other questions may require this information in order to proceed, and a brief note beats wasted time reconfirming your conclusion while trying to answer a subsequent question. Your O-Chem passage map will begin to develop as you answer your questions, but before jumping into answering them, you will likely have very little to jot down.

The passage below is an example of an Information Presentation passage (of the second type described previously). Note the minimal highlighting.

The small milkweed bug, Lygaeus kalmii, produces and emits a number of C5−C8 alkenals. Some of these small, fragrant, organic molecules are used to attract conspecific males or females for mating; thus, they act as sex pheromones. Others of the molecules are strongly malodorous and are used for defense.

Collaborating scientists in Brazil, the Netherlands, and Maryland have recently developed a method of noninvasive sampling and identification of these small organic molecules from live insects. This method involves the use of gas chromatography and mass spectrometry for the separation and identification of the components of the mixture of molecules involved in the sex- and defense-pheromone response in L. kalmii. Several of the molecules identified in this manner are shown in Figure 1.

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Figure 1 Molecules Identified Using Gas Chromatography and Mass Spectrometry

In addition to its mass spectrum, Molecule A, shown below, was also identified by its 1H NMR spectrum:

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Molecule A

Remember not to get bogged down in spectroscopic data before a question specifically asks you to analyze it. Here is an example of a passage map for the passage above. This is what you might jot down on your scratch paper:

P1 — alkenals

P2 — separation and identification of alkenals

P3 — NMR data

The passage below is another example of an Information Presentation passage (of the third type described previously). While the passage has much more text to wade through, only one small piece of it proves to be important in an Explicit question (addressed in detail later). Highlighted items are related to the main point of each paragraph, include new definitions, or provide examples of phenomena. The figures presented are more complex than those in the first passage, and the questions related to them are likely to be more involved as well.

Dyes are ionizable, aromatic compounds that absorb visible light due to the presence of a highly conjugated system of p orbitals. The observed color is one that is complementary to the wavelength of light absorbed by the molecule (complementary color pairs are red/green, orange/blue, and yellow/violet). Dyes bind to the materials to be colored, such as fabrics or paper, through inter- and intramolecular interactions, including hydrogen bonds, ionic interactions, covalent bonds, and coordinate covalent bonds. The stronger the interaction between dye molecule and fiber, the more permanent the color will be. When a dye covalently bonds to a fiber, it becomes a part of the fabric itself and cannot be washed away.

Two of the most common dye types are mordant dyes and direct dyes. A mordant is a polyvalent metal ion (usually Al3+ or Fe3+) that forms a coordination complex with certain dyes. Mordants chelate to the fabric as well as the dye molecule, thereby improving their colorfastness. Mordant dyes are primarily used on protein-based fibers such as wool, silk, angora, and cashmere since the mordant can bind to the constituent amino acids of these fibers. Direct dyes are typically charged molecules, and interact with the material to be dyed through ionic forces or hydrogen bonding. As such they tend to bleed more than mordant dyes. Direct dyes are more commonly used on cellulose fibers such as cotton, linen, or hemp.

Azo dyes, a subclass of direct dyes, may be used in a dyeing technique in which an insoluble azo compound is produced directly onto or within a fiber. This is achieved by treating the fiber first with a diazonium component, followed by a coupling component. With suitable adjustment of dye bath conditions the two components react to produce the required insoluble azo dye. The coupling reagent used in the final step is typically a molecule containing either a phenolic hydroxyl group or an arylamine. The synthesis of methyl orange, an azo dye, is shown in Figure 1.

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Figure 1 Synthesis of methyl orange

Figure 2 below represents the mechanism of the diazonium coupling reaction in the synthesis of methyl orange.

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Figure 2 Mechanism of diazonium coupling

This is what you might jot down on your scratch paper for the passage above:

P1 — what dyes are and how they work

P2 — Definitions: mordant dye vs. direct dyes, fiber types dyed

P3 — Structure requirements for diazocoupling

2.6 TACKLING THE QUESTIONS

It’s always best to answer all the freestanding questions in any science section of the MCAT before beginning to read the passages. By starting with some Memory questions, you can jump start your brain, earn some quick points, and ensure you’ve answered some of the easiest questions on the test before time runs out.

The Organic Chemistry passage-based questions are some of the most straightforward ones on the entire exam and, as a result, some of the quickest ones to answer. It may be a wise strategy to consider doing the O-Chem passages before the Biology, Physics, or General Chemistry ones to help bank up some extra time to spend on the wordier, more involved Biology passages.

However, you should also consider starting with whichever subject you feel the most comfortable with, saving your more difficult subject for last. Whatever subject you choose, do all of the passages in one subject first before switching. In addition, do the passages within a subject in the order with which you feel most comfortable, leaving the topic you struggle with most, or the passage that appears to be the most difficult, for last. Within the passages themselves, tackle the easier questions first, leaving the most time consuming ones for last.

O-Chem Memory Questions

These questions can be answered directly from prior knowledge. You can often recognize this question type by the length of the answer choices; one- or two-word answer choices are a good indication that you have the answer to these questions in your head already. Freestanding questions are commonly Memory questions since there is no passage to refer to. In addition, O-Chem passages often have “hidden” FSQs associated with them. This is another good reason to get to the questions quickly, rather than getting stuck reading details within the passage text.

Here is a true freestanding question that is also a Memory question:

Which of the following acetylating conditions will convert diethylamine into an amide at the fastest rate?

A) Acetic acid / HCl

B) Acetic anhydride

C) Acetyl chloride

D) Ethyl acetate

Your first step to attacking this question should be to consider what type of reaction is described. The conversion of an amine to an amide is a nucleophilic addition-elimination, where the amine acts as the nucleophile. Therefore, you’re looking for the answer choice with the best electrophile, thereby increasing the reaction rate. Knowing the relative reactivities of carboxylic acids derivatives (amide < ester < anhydride < acid halide) allows you to eliminate choices B and D. In order to choose between the remaining answers that include a carboxylic acid and an acid derivative, rely on your fundamentals. Ask yourself: How would an amine be expected to behave under each set of conditions? When you consider that amines are not only nucleophilic but also basic, you can deduce that they will be protonated by both the HCl and the acetic acid to yield a non-nucleophilic conjugate acid under the conditions of answer choice A. The nucleophilic addition reaction is therefore faster with the acid chloride derivative, making answer choice C correct.

O-Chem Explicit Questions

These questions have answers that are explicitly stated in the passage. To answer them correctly, for example, may just require finding a definition, reading a graph, or making a simple connection. Explicit questions are much more common in passages of the test that rely more on reading comprehension. Since chemical structures are the most common source of referenced information in an O-Chem passage, Explicit questions in this section might ask you to identify the number of chiral centers in a given molecule, or to identify whether a particular functional group is present or not.

Here’s an example of an Explicit question from the azo dye passage:

Mordant dyes are used in biological assays in addition to the textile industry. Which of the following biologically important molecules is most likely to be labeled by a mordant dye?

A) Glycogen

B) Chromatin

C) Cholesterol

D) Starch

You should recognize the term “mordant” as a new term you highlighted while reading the passage, so go back to the text to retrieve the important information. The passage states that mordants generally bind to protein-based fibers. Without this information, you might be able to eliminate choices A and D (glycogen and starch) since they are both carbohydrates, and as such, are not likely to be the answer. With the passage information at your disposal, however, this becomes a bit of a Memory question, and you need only determine which of your answer choices contain proteins. Cholesterol, a lipid, can be eliminated in addition to the two carbohydrates, leaving choice B as the correct answer (note that chromatin contains both proteins and DNA).

O-Chem Implicit Questions

These questions require you to apply knowledge to a new situation or make a more complex connection; the answer is typically implied by the information in the passage. Answer choices are generally longer, and may come in two parts, where the second half provides an explanation for the first. As mentioned before, the relevant information in the passage is often a molecular structure, but the analysis required to answer the question is more involved than for Explicit questions that rely on structures. Implicit style questions are the most common types of O-Chem questions.

Here’s an example of an Implicit question from the azo dye passage:

The diazonium coupling reaction in Figure 2 is faster than most electrophilic substitutions of benzene. Which of the following statements best explains this fact?

A) The diazonium ion is an electron withdrawing substituent, making its benzene ring a better electrophile than benzene.

B) The diazonium ion is a good nucleophile.

C) The dimethylamino group is an electron donating substituent, making its benzene ring a better electrophile than benzene.

D) The dimethylamino group is an electron donating substituent, making its benzene ring a better nucleophile than benzene.

Since these answer choices are relatively long (and most have a second clause), try to use POE to eliminate choices based on obvious false statements in the first part of the answer. Remember, if any part of an answer choice is false, the entire statement can be eliminated. The first half of all the choices makes a statement about the inductive effects of substituents, or, in the case of answer choice B, the nucleophilicity of a compound. Refer to the structures in Figure 2. You should note that the diazonium ion is positively charged and therefore electron deficient. Since nucleophiles are by definition electron rich, choice B can be eliminated. The first halves of the remaining answer choices are all valid statements, since a positively charged substituent will pull electron density toward it, while an amine with a lone pair of electrons on the nitrogen will push electron density toward the ring. This question requires a more critical approach to distinguish between answer choices.

You should identify this as an Implicit question since it asks you to compare a new reagent to one you might already be familiar with. Consider, then, what you already know about benzene. Since benzene has six π electrons and is electron rich, it should behave as a nucleophile. This fundamental piece of information about the reactivity of benzene allows you to eliminate choices A and C. It does not matter whether the indicated substituents in Figure 2 make benzene a better or worse electrophile, since in the context of this reaction benzene behaves as a nucleophile. The remaining answer (choice D) is not only internally consistent but also answers the question.

Content Categories

O-Chem questions can be further classified from a content perspective into four main categories. Instead of trying to memorize a lot of detailed information, try to generalize as much as possible, and focus on the fundamentals of structure and stability when approaching questions. Remember that the MCAT is more likely to ask you to apply fundamental concepts to novel situations rather than ask you to recall an exception to a rule and regurgitate trivia. Just about every O-Chem question can be put into one of the following five categories:

Structure

Questions are generally about functional groups, stereochemistry, isomers, electron density (nucleophiles vs. electrophiles), and nomenclature.

Stability

This generally refers to stability of products or reaction intermediates. These questions often ask about inductive effects, resonance, steric strain, torsional strain, ring strain, etc.

Laboratory practices

These questions may ask you to identify an appropriate separation technique (extraction, chromatography, distillation, etc.) for a given mixture of compounds, or ask you to interpret/predict the results of a separation procedure. You might also be asked to choose an appropriate spectroscopic technique (IR, NMR, mass spec, UV-vis, etc.) to identify a compound, or interpret spectroscopic data.

Predict the product

Given a starting material and reaction conditions, choose the major product of the reaction. This will only be a one step synthesis; no multi-step processes will be presented. These questions will generally be associated with a passage in which a reaction type is explained in detail rather than be a freestanding question.

Finally, let’s take a look at some sound advice about how to manage your time effectively while answering individual questions, as well as good strategies or rules of thumb you can apply to attack some of the most common formats of questions you’ll see on the MCAT.

ORGANIC CHEMISTRY QUESTION STRATEGIES

1. Remember that Process of Elimination is paramount! The strikeout tool allows you to eliminate answer choices; this will improve your chances of guessing the correct answer if you are unable to narrow it down to one choice.

2. Answer the straightforward questions first. Leave questions that require analysis of experiments and graphs for later.

3. Make sure that the answer you choose actually answers the question, and isn’t just a true statement.

4. I-II-III questions: Always work between the I-II-III statements and the answer choices. Unfortunately, it is not possible to strike out the Roman numerals, but this is a great use for scratch paper notes. Once a statement is determined to be true (or false), strike out answer choices that do not contain (or do contain) that statement as appropriate.

5. Ranking questions: Look for an extreme in whatever is being ranked, then look at the answer choices. Use the strikeout feature to eliminate choices as you go. In some cases, you may immediately get the answer as only one choice lists the appropriate option as “least” or “greatest.” Usually you will, at minimum, be able to strikeout two answer choices. Then just examine the remaining possibilities to determine which of the items at the other end of the ranking can be correct.

6. 2 × 2 style questions: These questions require you to know two pieces of information to get the correct answer, and are easily identified by their answer choices, which commonly take the form A because X, B because X, A because Y, B because Y. Tackle one piece of information at a time, which should allow you to quickly eliminate two answer choices.

7. LEAST/EXCEPT/NOT questions: Don’t get tricked by these questions that ask you to pick the answer that doesn’t fit (the incorrect or false statement). It’s often good to use your scratch paper and write a T or F next to answer choices A—D. The one that stands out as different is the correct answer!

8. If you read a question and do not know how to answer it, look to the passage for help. It is likely that the passage contains information pertinent to answering the question, either within the text or in the form of experimental data.

9. Math: Any questions that involve calculations should be left for last (there aren’t many in O-Chem, but they happen). You should always round numbers and estimate while working out calculations on your scratch paper.

10. Don’t ever leave a question blank since there is no penalty for guessing.

A Note About Flashcards

Contrary to popular belief, flashcards are NOT the best way to study for the MCAT. For most of the exams you’ve taken previously, flashcards were probably helpful. This was because those exams mostly required you to regurgitate information, and flashcards are pretty good at helping you memorize facts. Remember, however, that the most challenging aspect of the MCAT is not that it requires you to memorize the fine details of content-knowledge, but that it requires you to apply your basic scientific knowledge to unfamiliar situations. Flashcards won’t help you do that.

There is only one situation in which flashcards can be beneficial, and that’s if your basic content knowledge is deficient in some area. For example, if you don’t know the definitions of all the possible types of isomers, flashcards can help you memorize those facts. Or, maybe you are unsure of some of the functional groups you need to know; flashcards can help you solidify that knowledge. Or you might find it useful to make flashcards to help you learn and recognize which amino acids are polar vs. nonpolar, or acidic vs. basic. (And remember that part of what makes flashcards useful is the fact that you make them yourself. Not only are they then customized for your personal areas of weakness, the very act of writing down information on a flashcard helps stick that information in your brain.) But other than straight, basic fact-memorization in your personal weak areas, you are better off doing and analyzing practice passages than carrying around a stack of flashcards.