Chapter 19

Problem 19-1

(a)

2-Methyl-3-pentanone

(b)

3-Phenylpropanal

(c)

2,6-Octanedione

(d)

trans-2-Methylcyclohexanecarbaldehyde

(e)

4-Hexenal

(f)

cis-2,5-Dimethylcyclohexanone

Problem 19-2

(a)

The structure of 3-methylbutanal. A four-carbon chain with an aldehyde group on the first carbon and a methyl group attached to the third carbon.

(b)

The structure of 4-chloro-2-pentanone. A five-carbon chain with a chlorine atom attached to the fourth carbon and a carbonyl group is on the second position.

(c)

The structure of phenylacetaldehyde. A benzene ring with the first carbon attached to C H 2 C H O group.

(d)

Cyclohexane ring in which one carbon has t-butyl (wedge) and H (dash) substituents, and two carbons away (clockwise) has C H O (wedge) and H (dash) groups.

(e)

The structure of 3-methyl-3-butenal. A four-carbon chain with a methyl group on the third carbon, sharing a double bond between the third and fourth carbons with aldehyde on first position.

(f)

A seven-carbon chain with a chloroethyl group attached to the second carbon by chloroethyl C 1, methyl attached to the fifth carbon, and aldehyde group attached to the first carbon.

Problem 19-3

(a)

Dess–Martin periodinane

(b)

1. O₃; 2. Zn

(c)

DIBAH

(d)

1. BH₃, then H₂O₂, NaOH; 2. Dess–Martin periodinane

Problem 19-4

(a)

HgSO₄, H₃O⁺

(b)

1. CH₃COCl, AlCl₃; 2. Br₂, FeBr₃

(c)

1. Mg; 2. CH₃CHO; 3. H₃O⁺; 4. CrO₃

(d)

1. BH₃; 2. H₂O₂, NaOH; 3. CrO₃

Problem 19-5

The structure of 1-cyano-1-hydroxycyclohexane. The first carbon of the cyclohexane ring is single-bonded to O H and C N groups.

Problem 19-6

The electron-withdrawing nitro group in p-nitrobenzaldehyde polarizes the carbonyl group.

Problem 19-7

CCl₃CH(OH)₂

Problem 19-8

Labeled water adds reversibly to the carbonyl group.

Problem 19-9

The equilibrium is unfavorable for sterically hindered ketones.

Problem 19-10

The first structure has cyclohexane double-bonded to N connected to the ethyl group. The second structure has cyclohexene linked to diethylamine at C 1 position.

Problem 19-11

The steps are the exact reverse of the forward reaction shown in Figure 19.7.

Problem 19-12

Cyclopentanone reacts with diethylamine, forming a compound where cyclopentene is linked at C 1 to a diethylamine group. C 1 and C 2 share a double bond.

Problem 19-13

(a)

H₂/Pd

(b)

N₂H₄, KOH

(c)

1. H₂/Pd; 2. N₂H₄, KOH

Problem 19-14

The mechanism is identical to that between a ketone and 2 equivalents of a monoalcohol, shown in Figure 19.11.

Problem 19-15

The structure of benzene with C 1 linked to C H connected to methyl and aldehyde group, C 5 position has an acetate group, plus ethanol.

Problem 19-16

(a)

Cyclohexanone + (Ph)₃P

\text{=}

CHCH₃

(b)

Cyclohexanecarbaldehyde + (Ph)₃P

\text{=}

CH₂

(c)

Acetone + (Ph)₃P

\text{=}

CHCH₂CH₂CH₃

(d)

Acetone + (Ph)₃P

\text{=}

CHPh

(e)

PhCOCH₃ + (Ph)₃P

\text{=}

CHPh

(f)

2-Cyclohexenone + (Ph)₃P

\text{=}

CH₂

Problem 19-17

The structure of beta-carotene. It consists of a long hydrocarbon chain comprising alternating single and double bonds. Both the ends have cyclohexene with methyl groups.

Problem 19-18

Intramolecular Cannizzaro reaction

Problem 19-19

Addition of the pro-R hydrogen of NADH takes place on the Re face of pyruvate.

Problem 19-20

The −OH group adds to the Re face at C2, and −H adds to the Re face at C3, to yield (2R,3S)-isocitrate.

Problem 19-21

The chemical structure of 3-cyanocyclohexanone.

Problem 19-22

(a)

3-Buten-2-one + (CH₃CH₂CH₂)₂CuLi

(b)

3-Methyl-2-cyclohexenone + (CH₃)₂CuLi

(c)

4-tert-Butyl-2-cyclohexenone + (CH₃CH₂)₂CuLi

(d)

Unsaturated ketone + (H₂C

\text{=}

CH)₂CuLi

Problem 19-23

Look for appearance of either an alcohol or a saturated ketone in the product.

Problem 19-24

(a)

1715 cm⁻¹

(b)

1685 cm⁻¹

(c)

1750 cm⁻¹

(d)

1705 cm⁻¹

(e)

1715 cm⁻¹

(f)

1705 cm⁻¹

Problem 19-25

(a)

Different peaks due to McLafferty rearrangement

(b)

Different peaks due to α cleavage and McLafferty rearrangement

(c)

Different peaks due to McLafferty rearrangement

Problem 19-26

IR: 1750 cm⁻¹; MS: 140, 84