MCAT Organic Chemistry Mechanisms Summary

Gold Standard MCAT Prep's MCAT Organic Chemistry Mechanisms and Reactions ('cheat sheet' notes)

Introduction | Summary I | Summary II | Basic Principles | IR Spectroscopy

Gold Standard MCAT Organic Chemistry Mechanisms

This MCAT Organic Chemistry Mechanisms and Reactions Summary is by no means an exhaustive review of MCAT Organic Chemistry. Our summary is only meant to highlight key mechanisms that are most helpful for the new MCAT. Understanding the basics, like electrostatics (opposites attract, like charges repel), helps to minimize memorization and maximize the understanding of MCAT reaction mechanisms.

For a list of topics for the new MCAT: MCAT Organic Chemistry Topics List. You can also access practice questions in our Free MCAT Practice Test, or our many full-length MCAT Practice Tests.

Gold Standard MCAT Organic Chemistry Mechanisms: Summary I

Common Organic Chemistry Reactions 1-22

Gold Standard MCAT Organic Chemistry Mechanisms: Summary II

Common Organic Chemistry Reactions 23-31

R = alkyl Et = ethyl X = halide R- MgX+ = Grignard reagent R- Li+ = alkyl lithium

Grignard reagents and alkyl lithiums are special agents since they can create new C—C bonds (see ORG 1.6).

*Reduction involves the addition of hydrogen or subtraction of oxygen.

  • Mild reducing agents add fewer hydrogens/subtract fewer oxygens.
  • Strong reducing agents add more hydrogens/subtract more oxygens.

Cross-referencing to The Gold Standard MCAT text are found below.

Gold Standard MCAT Organic Chemistry Mechanisms: Basic Principles

Most reactions presented can be derived from basic principles (i.e. ORG 1.6, 7. 1). Many of the reactions are cross-referenced for further information.

  • An acid chloride reacts with a Grignard reagent to produce a tertiary alcohol. See ORG 1.6, 9.1.
  • An acid chloride reacts with a primary or secondary amine to produce an amide. See ORG 9.3 & 11.2.
  • A carboxylic acid reacts with SOCl2 or PCl5 to produce an acid chloride. See ORG 9.1
  • An acid chloride reacts with an alcohol (e.g. ethanol) to produce an ester. See ORG 9.4.
  • An amide reacts with LiAlH4 to produce an amine. See ORG 8.2, 9.3.
  • A carboxylic acid reacts with an alcohol (e.g. ethanol) to produce an ester. See ORG 8.2.
  • An ester reacts with LiAlH4 to produce a primary alcohol. See ORG 8.2, 9.4.
  • A carboxylic acid reacts with base to produce a carboxylate anion. See CHM 6.3 & ORG 8.1.
  • An ester reacts with a Grignard reagent to produce a tertiary alcohol. See ORG 1.6, 8.1.1, 9.4.
  • A Grignard reagent reacts with carbon dioxide to produce a carboxylic acid. See ORG 8.1.1.
  • A nitrile reacts with aqueous acid to produce a carboxylic acid. See ORG 8.1.1.
  • A carboxylate ion reacts with ethyl iodide to produce an ester.
  • An alkyl halide reacts with Mg/ether to produce a Grignard reagent.
  • An alkyl halide reacts with NaCN to produce a nitrile. See ORG 6.2.3.
  • A nitrile reacts with LiAlH4 to produce an amine. See ORG 8.2.
  • A primary alcohol reacts with HBr to produce an alkyl halide.
  • An acid chloride reacts with NaBH4 to produce a primary alcohol. See ORG 8.2, 9.1.
  • A primary alcohol reacts with CrO3/pyridine to produce an aldehyde. See ORG 6.2.2, 7.2.1.
  • A acid chloride reacts with H2/Pd/C to produce an aldehyde. See ORG 7.1, 7.2.1, 9.1.
  • An aldehyde reacts with NaBH4 to produce a primary or secondary alcohol. See ORG 7.1, 8.2.
  • An aldehyde reacts with KMnO4 to produce a carboxylic acid. See ORG 7.2.1, 8.1.1.
  • A carboxylic acid reacts with LiAlH4 to produce a primary alcohol. See ORG 8.2.
  • An imine reacts with NaBH4 to produce a secondary amine. See 7.2.3, 8.2.
  • An aldehyde reacts with a primary amine to produce an imine. See ORG 7.2.3.
  • An aldehyde reacts with a Grignard reagent and ether to produce a secondary alcohol. See ORG 1.6, 7.1.
  • An aldehyde reacts with aqueous NaCN. See ORG 7.1.
  • A secondary alcohol reacts with Na2CrO7 or CrO3/pyridine to produce a ketone. See ORG 6.2.2.
  • A ketone reacts with NaBH4 to produce a secondary alcohol. See ORG 7.2.1.
  • An acetal reacts with aqueous acid to produce an aldehyde. See ORG 7.2.1/2.
  • An aldehyde reacts with an alcohol (e.g. ethanol) and acid to produce an acetal. Note that using with less EtOH/H+, a hemiacetal will form. See ORG 7.2.2.
  • A ketone reacts with a Grignard reagent to produce a tertiary alcohol. See ORG 1.6, 9.

Gold Standard MCAT Organic Chemistry Review: IR Spectroscopy

Memorize at least the following IR spectra data for the MCAT:

  • Approx. 3300 cm-1 for -OH (alcohol functional group)
  • Approx. 1700 cm-1 for C=O (carbonyl functional group)

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