Ch. 18

Question 1

What is the product of this reaction?

Answer 1

acetal formation

Question 2

What is the product of this reaction?

Answer 2

cyanohydrin formation

Question 3

What is the product of this reaction?

Answer 3

conjugate addition

Question 4

What is the product of this reaction?

Answer 4

nitrile heterolysis

Question 5

Which types of nucleophiles do direct addition? (1,2)

Answer 5

organometallics and hydrides

Question 6

Will NaCN do direct addition or conjugate addition?

Answer 6

conjuage addition (1,4)

Question 7

what is the purpose of a catalyst?

Answer 7

to decrease activation energy and increase the reaction rate

Question 8

What do you need for an acid catalyzed formation of an acetal?

Answer 8

a weak nucleophile in excess (H₂O, CH₃OH, alcohols, etc)

an acid catalyst (H₂SO_4, HCl, etc)

Question 9

Will acetals form in basic conditions?

Answer 9

No

Question 10

how do you reverse the formation of an acetal?

(acetal –> carbonyl)

Answer 10

add H₂O in excess

(this is a hydrolysis reaction)

Question 11

do weak nucleophiles prefer direct (1,2) or conjugate (1,4) addition?

Answer 11

conjugate (1,4)

Question 12

What is the product of this reaction?

Answer 12

imine/hydrazone/oxime formation

Question 13

What is the product of this reaction?

Answer 13

reductive amination

Question 14

What is the product of this reaction?

Answer 14

Question 15

What is the product of this reaction?

Answer 15

enamine formation

Question 16

What is the product of this reaction?

Answer 16

Question 17

How can you reverse an imine?

Answer 17

add excess H₂O under acidic conditions

Question 18

How do you identify a hemiacetal molecule?

Answer 18

Look for carbon atoms that are bonded to two oxygen atoms. If one of the two oxygen atoms is part of an OH group, the molecule is a hemiacetal.

Question 19

How do you identify an acetal molecule?

Answer 19

Look for carbon atoms that are bonded to two oxygen atoms. If both of the oxygen atoms are part of OR groups, the molecule is an acetal.

Question 20

What is the first step in an acid-catalyzed reaction?

Answer 20

proton transfer from the acid-catalyst

Question 21

What is the first step in the hydrolysis of nitriles under basic conditions?

(reversing nitriles)

Answer 21

the base will dissociate into X+ and OH-, the OH- will attack the partitally positive carbon

Question 22

What is the product of this reaction?

Answer 22

Wolff-Kishner Reduction

NOT TESTED ON MECHANISM

Question 23

What types of nucleophiles prefer conjugate additon? (1,4)

Answer 23

Weak Nucleophiles

(HCN, CH₂CH₃SH, NaCN)

Question 24

What is the first step in a base-catalyzed reaction?

Answer 24

The base (^-OH) takes a proton off of the weak nucleophile to make it a strong nucleophile

i.e. a proton transfer from the nucleophile to the base

Question 25

What is the product of the following reaction?

Answer 25

an enamine

Question 26

What is the product of the following reaction?

Answer 26

nitrile –> primary amide

Question 27

What is the product of the following reaction?

Answer 27

Aldol Reaction

OH attaches to beta Carbon