MCAT Organic Chemistry Review

Aldehydes and Ketones I: Electrophilicity and Oxidation—Reduction

Practice Questions

1.    All of the following are true with respect to carbonyls EXCEPT:

1.    the carbonyl carbon is electrophilic.

2.    the carbonyl oxygen is electron-withdrawing.

3.    a resonance structure of functional group places a positive charge on the carbonyl carbon.

4.    the π electrons are mobile and are pulled toward the carbonyl carbon.

2.    Order the following compounds by increasing boiling point: butane, butanol, butanone

1.    Butanol < butane < butanone

2.    Butane < butanone < butanol

3.    Butanone < butane < butanol

4.    Butane < butanol < butanone

3.    What is the product of the reaction below?

1.   

2.   

3.   

4.   

4.    What is the product of the reaction below?

1.   

2.   

3.   

4.   

5.    What is the product of the reaction below?

1.    C3H7OH

2.    C2H5COOH

3.    C3H6CHO

4.    CH3COOH

6.    What is the product of the reaction below?

1.   

2.   

3.   

4.   

7.    What is the product of the reaction between benzaldehyde and an excess of ethanol (CH3CH2OH) in the presence of anhydrous HCl?

1.   

2.   

3.   

4.   

8.    Hemiacetals and hemiketals usually keep reacting to form acetals and ketals. Why is it difficult to isolate hemiacetals and hemiketals?

1.    These molecules are unstable.

2.    The hydroxyl group is rapidly protonated and lost as water under acidic conditions, leaving behind a reactive carbocation.

3.    The molecules are extremely basic and react rapidly with one another.

1.    I only

2.    I and II only

3.    II and III only

4.    I, II, and III

9.    In a hemiacetal, the central carbon is bound to:

1.    –OH, –OR, –H and –R.

2.    –H, –OR, –OR, and –R.

3.    –OH, –OR, –R, and –R.

4.    –OR, –OR, –R, and –R.

10.In a reaction between hydrogen cyanide, butyraldehyde, and ethylmethylketone, which compounds will come together to form the major product?

1.    Butyraldehyde and hydrogen cyanide

2.    Ethylmethylketone and butyraldehyde

3.    Hydrogen cyanide and ethylmethylketone

4.    No reaction will occur.

11.Which of the following describe(s) pyridinium chlorochromate (PCC)?

1.    An oxidant that can form aldehydes from primary alcohols

2.    An oxidant that can form carboxylic acids from primary alcohols

3.    An oxidant that can completely oxidize secondary alcohols to ketones

1.    I only

2.    I and II only

3.    I and III only

4.    I, II, and III

12.To form a geminal diol, which of the following could attack a carbonyl carbon?

1.    Hydrogen peroxide

2.    Water

3.    Potassium dichromate

4.    Ethanol

13.In a reaction between ammonia and glutaraldehyde, what is the major product?

1.    An imine

2.    A cyanohydrin

3.    An aldehyde with a substituted ring

4.    An alcohol

14.Which of the following can be used to reduce a ketone to a secondary alcohol?

1.    CrO3

2.    KMnO4

3.    LiAlH4

4.    Ag2O

15.Imines naturally tautomerize to form:

1.    oximes.

2.    hydrazones.

3.    semicarbazones.

4.    enamines.

PRACTICE QUESTIONS