Question 1

Identify the missing reagent for the reaction.

Accepted Answer

The overall reaction is a substitution of an aldehyde hydrogen with a methyl group. There is no direct way of achieving this transformation, so consider the methods you know for generating a carbon-carbon bond. A Grignard addition to the aldehyde would generate a secondary alcohol. The alcohol could then be oxidized to the ketone.

Question 2

The conversion of alkyl azides into primary amines through a procedure called the Staudinger reaction is shown.
   The mechanism of the first part of the reaction is conceptually similar to the Wittig reaction that we've talked about, where an ylide reacts with a carbonyl to yield an oxaphosphetane, which then rearranges to an alkene and triphenylphosphine oxide.
   Provide an arrow pushing mechanism for the first part of the Staudinger reaction, the reaction of triphenylphosphine (TPP) and an alkyl azide to produce an iminophosphorane and nitrogen gas.

Accepted Answer

The answer of The conversion of alkyl azides into primary...

Question 3

Provide a detailed, arrow-pushing mechanism for the transformation. Show all reactive intermediates. (It is not necessary to show every resonance structure for appropriate intermediates.)

Accepted Answer

This reaction is known as the pinacol rearrangement, where a 1,2-diol under acidic conditions will rearrange to give a carbonyl. The mechanism involves:

Question 4

Predict the major organic product in the box provided. There may be more than one acceptable answer. If you believe no reaction would occur, write NR. Denote stereochemistry where appropriate.

Accepted Answer

These conditions ind

Question 5

Two students working in a laboratory are tasked to synthesize compound B from compound A. The first student thinks that a dehydration reaction, treating A with strong acid and heat, will do the trick. The second student disagrees and says the reaction will not work as intended.
a. Explain why the second student is right and predict the more likely product (C) of the reaction.
   ​
b. If you could start with cyclohexanone, how would you prepare B? You may use any other reagents you want. Show all steps and intermediates, but reaction mechanisms are not necessary.

Accepted Answer

a. The alcohol dehydration is an E1 reac

Question 6

Identify the missing reagent for the reaction.

Accepted Answer

The overall reaction is conver

Question 7

Deduce the structure of the missing starting material.

Accepted Answer

Working backwards, the alcohol and pheny

Question 8

For each pair of reactions, circle "faster" for the one you believe is faster.
a. 
   ​
b.

Accepted Answer

a. The unsubstituted aldehyde will react

Question 9

Outline a synthesis to achieve this transformation.

Accepted Answer

The overall reaction looks like a simple

Question 10

Predict the major organic product of the reaction. If you believe no reaction would occur, write NR and explain why.

Accepted Answer

This reaction will r

Question 11

Treatment of a mixture of cyclopentanone (A) and acetone cyanohydrin (B) with a catalytic amount of base (NaOH) leads to an equilibration to form a mixture of A, B, cyclopentanone cyanohydrin (C), and acetone (D). Provide an arrow pushing mechanism for the transformation in the forward direction (A + B → C + D) as written.

Accepted Answer

A catalytic amount of base present can d

Question 12

These two alkenes were prepared by Wittig reactions. In the corresponding box show one set of the carbonyl and ylide reaction partners that would make each alkene. There may be more than one correct answer; just show one. Remember the general form for an ylide is Ph3P=CR2.
​a. 
   ​
b.

Accepted Answer

For each case, working backwards, you sh

Question 13

Which of the reactions would have the largest Keq?

Accepted Answer

A)  X = H 
B)  X = OEt 
C)  X = CN 
D)  X = NO2 
E)  X = Br 
A)  X = H 
B)  X = OEt 
C)  X = CN 
D)  X = NO2 
E)  X = Br

Question 14

Outline a synthetic route for the transformation:

Accepted Answer

The product has added carbon between the

Question 15

Provide detailed, arrow-pushing mechanisms for the two-step transformation. Show all reactive intermediates, and all proton transfer steps. (It is not necessary to show every resonance structure for intermediates.)

Accepted Answer

The first step is formation of

Question 16

Outline a synthesis for the transformation. Identify the missing reagents.

Accepted Answer

The overall reaction looks like the brom

Question 17

In the reaction of H2O at pH 2 with these compounds, the equilibrium would most favor the geminal dihydroxy product or hydrate for which starting material?

Accepted Answer

A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D 
E)  can't tell without knowing the corresponding trend for the rates of the reactions 
A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D 
E)  can't tell without knowing the corresponding trend for the rates of the reactions

Question 18

In each set of reactions, circle the one with the larger equilibrium constant (lies further to the right).
a
.
   ​b.

Accepted Answer

a.
 @#IMG-DLM& In both cases, a carbonyl is treate

Question 19

Draw the structure of the major organic product for the reaction. If no reaction would occur, write NR. Unless otherwise stated assume there is enough of any reagent to do all the normal reactions. Reaction mechanisms are not necessary.

Accepted Answer

These conditions indicate the

Question 20

Predict the major organic product for the reaction in the box provided. If you believe no reaction would occur, write NR.

Accepted Answer

A semicarbazide is t

Exam 19: The Chemistry of Aldehydes and Ketones

Identify the missing reagent for the reaction.

Provide a detailed, arrow-pushing mechanism for the transformation. Show all reactive intermediates. (It is not necessary to show every resonance structure for appropriate intermediates.)

Predict the major organic product in the box provided. There may be more than one acceptable answer. If you believe no reaction would occur, write NR. Denote stereochemistry where appropriate.

Identify the missing reagent for the reaction.

Deduce the structure of the missing starting material.

For each pair of reactions, circle "faster" for the one you believe is faster. a. ​ b.

Outline a synthesis to achieve this transformation.

Predict the major organic product of the reaction. If you believe no reaction would occur, write NR and explain why.

These two alkenes were prepared by Wittig reactions. In the corresponding box show one set of the carbonyl and ylide reaction partners that would make each alkene. There may be more than one correct answer; just show one. Remember the general form for an ylide is Ph3P=CR2. ​a. ​ b.

Which of the reactions would have the largest Keq?

Outline a synthetic route for the transformation:

Provide detailed, arrow-pushing mechanisms for the two-step transformation. Show all reactive intermediates, and all proton transfer steps. (It is not necessary to show every resonance structure for intermediates.)

Outline a synthesis for the transformation. Identify the missing reagents.

In the reaction of H2O at pH 2 with these compounds, the equilibrium would most favor the geminal dihydroxy product or hydrate for which starting material?

In each set of reactions, circle the one with the larger equilibrium constant (lies further to the right). a . ​b.

Draw the structure of the major organic product for the reaction. If no reaction would occur, write NR. Unless otherwise stated assume there is enough of any reagent to do all the normal reactions. Reaction mechanisms are not necessary.

Predict the major organic product for the reaction in the box provided. If you believe no reaction would occur, write NR.

Chemical Bonding and Chemical Structure

Alkanes and Organic Nomenclature

The Curved-Arrow Notation, Resonance, Acids and Bases, and Chemical Equilibrium

Introduction to Alkenes and Alkynes

Addition Reactions of Alkenes and Alkynes

Principles of Stereochemistry

Cyclic Compounds and Reaction Stereochemistry

Nomenclature and Noncovalent Intermolecular Interactions

The Chemistry of Alkyl Halides

Free-Radical Reactions, Main-Group Organometallic Compounds, and Carbenes

The Chemistry of Alcohols and Thiols

The Chemistry of Ethers, Epoxides, Glycols, and Sulfides

Introduction to Spectroscopy

Nuclear Magnetic Resonance Spectroscopy

Dienes and Aromaticity

The Chemistry of Benzene and Its Derivatives

Allylic and Benzylic Reactivity

The Chemistry of Aryl Halides, Vinylic Halides, and Phenols

The Chemistry of Carboxylic Acids

The Chemistry of Carboxylic Acid Derivatives

The Chemistry of Enolate Ions, Enols, and Α,β-Unsaturated Carbonyl Compounds

The Chemistry of Amines

Carbohydrates

The Chemistry of Thioesters, Phosphate Esters, and Phosphate Anhydrides

The Chemistry of the Aromatic Heterocycles and Nucleic Acids

Amino Acids, Peptides, and Proteins

Pericyclic Reactions

Filters

For each pair of reactions, circle "faster" for the one you believe is faster. a. b.

These two alkenes were prepared by Wittig reactions. In the corresponding box show one set of the carbonyl and ylide reaction partners that would make each alkene. There may be more than one correct answer; just show one. Remember the general form for an ylide is Ph₃P=CR₂. a. b.

Which of the reactions would have the largest K_eq?

In the reaction of H₂O at pH 2 with these compounds, the equilibrium would most favor the geminal dihydroxy product or hydrate for which starting material?

In each set of reactions, circle the one with the larger equilibrium constant (lies further to the right). a . b.