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MCAT: Organic Chemistry


The MCAT can be a daunting test to take, especially with how difficult pre-requisite classes already are. For many of us, Organic Chemistry is a class that we want to forget. However, it is a subtopic within the MCAT. Many students spend too much time memorizing chemical reactions. Instead, knowing the basic principles will ensure proper application and getting the 6-12 questions of Organic Chemistry content correct. Here are three main tips you should utilize when tackling this subtopic. 


Tip 1: Memorize the structures of the functional groups. 


Just like you have to memorize amino acids, focus on remembering the structures of functional groups. You can use your notes from your orgo classes or the MCAT prep resources you have. It’s important to know the structures of aldehydes because you can recollect their properties. For instance, aldehydes have an electrophilic carbonyl carbon, and the hydrogen connected to the carbonyl carbon is not going to sterically hinder any nucleophiles. You can easily determine this from the structure, so knowing all the functional group structures will help answer any questions about specific chemical properties and save time from routine memorization of each functional group. 


Tip 2: Recollect the properties of the functional groups to determine their reactions. 


As mentioned in the previous point, remembering the structure of the functional group can help with knowing the properties of the functional group. For example, when drawing the carboxylic acid structure, there are parts of the molecule that interact differently. If a question was asked about whether the oxygen double-bonded to the central carbon or the central carbon is more electronegative, the answer would be oxygen! This is because oxygen desires electrons more compared to carbon (higher electronegativity). The oxygen will pull on the electrons more, giving it a slight negative charge, while the central carbon will have a slight positive charge. Why is this important? Knowing that the carbon has a positive charge indicates that it’s reactive; a nucleophile can attack the central carbon in a reaction. 


Tip 3: Comprehend common experimental techniques used in organic chemistry such as spectroscopy, separations, and purifications. 


Along with the functional groups, the MCAT expects students to know the procedures you learned in your organic chemistry lab classes. Be sure to go through your laboratory book and lecture material to review any information. 


A general tip when missing any practice MCAT question is to review that question, record what information you needed to answer the question correctly, and study the missed information. This will allow further review of the question. Here are some practice questions with explanations from the source linked at the end; for further resources, please click on the source as well as using sources like Quizlet and Anki and other MCAT guides for additional practice questions. Keep studying and you got this!


1. A researcher performs an organic reaction in which a benzene with an alcohol substituent turns into a benzene with an aldehyde substituent. Which of the following peaks may appear for the product in IR spectroscopy?

A) Broad, 3500 cm-1

B) Sharp, 3500 cm-1

C) Broad, 1700 cm-1

D) Sharp, 1700 cm-1

2. Which of the following best describes why protic solvents decrease nucleophilicity?

A) Protic solvents are too sterically bulky and prevent the nucleophile from contacting the electrophile.

B) Protic solvents alter the chemical properties of the electrophile to decrease the reaction efficiency.

C) Protic solvents can hydrogen bond with the nucleophile, thereby decreasing the frequency of nucleophilic attack.

D) Protic solvents introduce a net positive charge to the nucleophile and decrease nucleophilicity.

3. A researcher is studying a molecule with three chiral centers. The researcher obtains a racemic mixture after several steps of purification. Which of the following stereochemical designations could the researcher have obtained?

A) S,S,S and R,S,R

B) R,S,S and S,R,R

C) R,S,R and S,R,R

D) S,S,R and S,S,S

4. Which of the following elements is MOST likely to be a strong nucleophile?

A) Hydroxide ion

B) Water

C) Ethanol

D) Tert-butanol

5. Which of the following standalone functional groups is most likely to undergo nucleophilic acyl substitution?

A) Primary alcohol

B) Aldehyde

C) Ketone

D) Carboxylic acid


Answers: 1. D, 2. C, 3. B, 4. A, 5. D



Thank you for reading, 

Siri Nikku 



 


Source (to explanations of answers and more review): 


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