Exam 2 - Reduction and Hemiacetal Formation

Question 1

___-mediated hemiacetal formation is MORE common than ___-mediated hemiacetal formation.

Answer 1

Acid-mediated is more common than Base-mediated.

Question 2

A ketone/aldehyde + ___ will create a hydrate.

Answer 2

H2O

Question 3

In Base-mediated hemiacetal formation, you react a ketone with ___ and ___ in order to make the hemiacetal.

Answer 3

ketone, ethanol, Na(+) (-)OR

Question 4

Basic conditions: Intermediates must be ___/___ charged.

Answer 4

neutral/negatively charged

Question 5

A ___ is when OH and OR are on the same C.

Answer 5

hemiacetal

Question 6

___ conditions: Intermediates must be neutral/positively charged.

Answer 6

Acidic conditions

Question 7

*Note: Oxygen nucleophiles are ___ nucleophiles.

Answer 7

weaker nucleophiles

Question 8

You can also add alkynes to ketones/aldehydes by adding ___ with a separate H3O+ acidic workup step afterward. This will create a new ___ group added on the central C, with the O becoming a ___.

Answer 8

Na(+) (-)alkyne-R, alkyne-R, OH

Question 9

You can also add CN to ketones/aldehydes by adding ___ and ___. This will create a new ___ group added on the central C, with the O becoming a ___.

Answer 9

Na(+) (-)CN, H2O, CN, OH

Question 10

In Acid-mediated hemiacetal formation, you can also use ___ instead of HCl with the ketone and ethanol.

Answer 10

pTsOH

Question 11

A ___ is when two OHs are on the same C.

Answer 11

hydrate

Question 12

Acidic conditions: Intermediates must be ___/___ charged. However, ___ ___ are okay.

Answer 12

neutral/positively charged, however non-basic anions (i.e. Br-, Cl-, etc.) are okay

Question 13

A hydrate is when two ___ are on the same ___.

Answer 13

two OHs on the same C.

Question 14

___ conditions: Intermediates must be neutral/negatively charged.

Answer 14

Basic conditions

Question 15

Ketones are generally ___ stable than aldehydes.

Answer 15

more

Question 16

A hemiacetal is when ___ and ___ are on the same ___.

Answer 16

OH and OR on the same C

Question 17

In Acid-mediated hemiacetal formation, you react a ketone with ___ and ___ in order to make the hemiacetal.

Answer 17

ketone, ethanol, HCl

Question 18

When a Ketone reacts with H2O, only 0.1% of the product is a hydrate. When Formaldehyde reacts with H2O, 99.9% of the product is a hydrate. This is because Cs have more ___ ___ (___ ___), so they cannot move as close to each other.

Answer 18

steric clash (are bigger)

Question 19

A ketone/aldehyde + H2O will create a ___.

Answer 19

hydrate

Question 20

Ketones are generally more stable than aldehydes because of more ___ and more ___ from ___ bonds.

Answer 20

more conjugation, more donation from C-H bonds