Additional Problems 10

Kirsten Kramer; Cassandra Lilly

Additional Problems 10

Visualizing Chemistry

Problem 10.11
Each of the following substances can be prepared by a nucleophilic addition reaction between an aldehyde or ketone and a nucleophile. Identify the reactants from which each was prepared. If the substance is an acetal, identify the carbonyl compound and the alcohol; if it is an imine, identify the carbonyl compound and the amine; and so forth.

(a)

A ball-and-stick model of a six-membered ring with two oxygen members, spaced with one carbon between them. That carbon has a methyl substituent.

(b)

A ball-and-stick model shows benzene ring linked to methylene group. This is linked to a nitrogen atom double bonded to carbon. This is linked to two methyl groups.

(c)

A ball-and-stick model of a cyclopentene linked to a cyclopentane with nitrogen atom.

(d)

A ball-and-stick model shows a benzene ring with a methyl group, C H linked to a hydroxyl. C H is also linked to two methyl groups.

Problem 10.12
The following molecular model represents a tetrahedral intermediate resulting from addition of a nucleophile to an aldehyde or ketone. Identify the reactants, and write the structure of the final product when the nucleophilic addition reaction is complete.

The ball-and-stick model shows a cyclopentane ring with nitrogen atom attached to three-carbon chain with hydroxyl and methyl group on the first carbon, and methyl group on the second carbon.

Mechanism Problems

Problem 10.13
Predict the product(s) and propose a mechanism for each of the following reactions:

(a)

The reaction shows butan-2-one with ethylene glycol using a hydrogen ion catalyst, producing an unknown product marked with a question mark.

(b)

The reaction shows acetone with (1S,2S)-cyclohexane-1, 2-diol using a hydrogen ion catalyst, yielding an unknown product marked with a question mark.

Problem 10.14
Predict the product(s) and propose a mechanism for each of the following reactions:

(a)

The reaction shows fused cyclohexane and cyclopentane rings with oxygen and methyl groups with hydrogen ion catalyst and water to yield an unknown product denoted by a question mark.

(b)

The reaction shows a compound with benzene attached to cyclopentane with oxygen, hydrogen, and methyl groups with hydrogen ion catalyst and water, yielding unknown product marked with a question mark.

Problem 10.15
Predict the product(s) and propose a mechanism for the following reaction:

The reaction shows pentan-3-one with hydroxylamine to yield an unknown product marked with a question mark.

Problem 10.16
Aldehydes and ketones react with thiols to yield thioacetals just as they react with alcohols to yield acetals. Predict the product of the following reaction, and propose a mechanism:

The reaction shows a cyclopentanone with two molecules of ethanethiol, in the presence of a proton catalyst to yield an unknown compound indicated by a question mark.

Naming Aldehydes and Ketones

Problem 10.17
Draw structures corresponding to the following names:

(a) Bromoacetone

(b) (S)-2-Hydroxypropanal

(c) 2-Methyl-3-heptanone

(d) (2S,3R)-2,3,4-Trihydroxybutanal

(e) 2,2,4,4-Tetramethyl-3-pentanone

(f) 4-Methyl-3-penten-2-one

(g) Butanedial

(h) 3-Phenyl-2-propenal

(i) 6,6-Dimethyl-2,4-cyclohexadienone

(j) p-Nitroacetophenone

Problem 10.18
Draw and name the seven aldehydes and ketones with the formula C₅H₁₀O. Which are chiral?

Problem 10.19
Give IUPAC names for the following compounds:

(a)

The structure shows cyclohexene ring with a carbonyl on the first carbon. A double bond is shared between the third and fourth carbons with a methyl group on the third.

(b)

The structure shows a central carbon bonded with hydrogen (wedge-bonded), a hydroxyl group (wedge-bonded), a hydroxymethyl group (dashed-bonded), and C H O group (dashed-bonded).

(c)

The structure shows cyclohexanone ring with a methyl group at the second carbon, a tert-butyl group at the fifth carbon, and a double bond between second and third.

(d)

The structure shows a five-carbon chain with, couting from the left, a methyl group on the second and a carbonyl on the third carbon.

(e)

The structure shows a four-carbon chain with, counting from the left, a hydroxyl group on the second carbon, and the fourth carbon part of a C H O group.

(f)

The structure shows a benzene ring with two C H O groups on the first and fourth carbon atoms.

Problem 10.20
Draw structures of compounds that fit the following descriptions:

(a) An aromatic ketone, C₉H₁₀O

(b) A diene aldehyde, C₇H₈O

Reactions of Aldehydes and Ketones

Problem 10.21
Predict the products of the reaction of (1) phenylacetaldehyde and (2) acetophenone with the following reagents:

(a) NaBH₄, then H₃O⁺

(b) Na₂Cr₂O₇, H₂SO₄

(c) NH₂OH, HCl catalyst

(d) CH₃MgBr, then H₃O⁺

(e) 2 CH₃OH, HCl catalyst

(f) HCN, KCN

Problem 10.22
How would you use a Grignard reaction on an aldehyde or ketone to synthesize the following compounds?

(a) 2-Pentanol

(b) 1-Butanol

(c) 1-Phenylcyclohexanol

(d) Diphenylmethanol

Problem 10.23
How might you carry out the following selective transformations? One of the two schemes requires a protection step. (Recall from Section 10.4 that aldehydes are more reactive than ketones toward nucleophilic addition.)

(a)

The reaction shows the conversion of 5-oxohexanal to 6-hydroxyhexan-2-one.

(b)

The reaction shows the conversion of 5-oxohexanal to 5-hydroxyhexanal.

Problem 10.24
Carvone is the major constituent of spearmint oil. What products would you expect from reaction of carvone with the following reagents?

The carvone structure shows a cyclohexanone ring with a methyl group at the second carbon and an isopropyl on the fifth. A double bond connects the second and third carbon.

(a) LiAlH₄, then H₃O⁺

(b) C₆H₅MgBr, then H₃O⁺

(c) H₂/Pd

(d) HOCH₂CH₂OH, HCl

General Problems

Problem 10.25
When 4-hydroxybutanal is treated with methanol in the presence of an acid catalyst, 2-methoxytetrahydrofuran is formed. Explain.

4-Hydroxybutanal reacts with methanol and hydrogen chloride to yield 2-methoxytetrahydrofuran. A methoxy group is attached to the C 2 position of tetrahydrofuran ring.

Problem 10.26
Reaction of 2-butanone with HCN yields a chiral product. What stereochemistry does the product have? Is it optically active?

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Fundamentals of Organic Chemistry Copyright © by Kirsten Kramer and Cassandra Lilly is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.