Chapter 10

Question 1

alcohol

Answer 1

compounds containing -OH (hydroxyl)

Question 2

thiol

Answer 2

compounds containing -SH (sulfhydrol)

Question 3

structure of Alchohols

Answer 3

the hydroxyl functional group is bonded to an sp3 hybridized carbon and the oxygen is sp3 hybridized, thus a sigma bond connects them

Question 4

physical properties of Alcohols

Answer 4

• polar due to -OH interactions
• have dipole dipole interactions and hydrogen bonding
• have relatively high boiling points
• polar alcohols are more soluble in water

Question 5

acidity and basicity of alcohols

Answer 5

-OH can function as both a weak acid and weak base

Question 6

reactions of alcohols with active metals

Answer 6

alcohols react with Li, Na and K to liberate H2 and form the corresponding metal alkoxides, which are reasonably strong bases

Question 7

reaction with phophorus tribromide

Answer 7

• alternative way to make bromoalkanes from primary and secondary alcohols
• mild reaction conditions required and rearrangements are not as typical as with HBr

Question 8

reaction with thionyl chloride (SOCl2) and thionyl bromide (SOBr2)

Answer 8

• common alternative to making chloroalkanes and bromoalkanes from primary and secondary carbons
• mild reaction conditions required and rearrangements are rare
• non nucleophilic base is typically added to (i) generate a small amount of the more reactive alkoxide to accelerate the reaction or (ii) neutralize the HCl or HBr that is generated during the reaction to prevent side reaction
• SN2 mechanism leads to inversion of chiral secondary alcohols

Question 9

formation of aryl and alkyl sulfonates

Answer 9

• similar to the reaction with SOCl2 that forms chlorosulfanites, are reactions with sulfonyl chlorides
• this turns an alcohol into an excellent leaving group, because the sulfate anion that leaves is very stable

Question 10

dehydration

Answer 10

elimination of water; a way to transform an alcohol to an alkene in the presence of acid and heat

Question 11

pinacol rearrangement

Answer 11

a particular acid-catalyzed dehydration with rearrangement that transforms vicuna diols into carbonyl functional groups

Question 12

oxidation

Answer 12

loss of electrons/hydrogens or gain of oxygen

-used to transform primary alcohols into aldehydes and carboxylic acids and secondary alcohols into ketones

Question 13

chromic acid oxidation

Answer 13

(H2CrO4)

• transforms primary alcohols into carboxylic acids
• transforms secondary alcohols into ketones
• tertiary alcohols do not oxidize

Question 14

pyridinium chlorochromate (PCC)

Answer 14

• transforms primary alcohols into aldehydes

- transforms secondary alcohols into ketons

Question 15

swern oxidation

Answer 15

• less toxic alternative to chromium based oxidation
• transforms primary alcohols into aldehydes
• transforms secondary alcohols into ketons
• stops at aldehyde
• reagents: 1. oxalyl chloride((COCL)2) + dimethyl sulfoxide (DMSO), 2. R-OH (alcohol), 3. tertiary amine (Et2N =TEA)

Question 16

Dess Martin Oxidation

Answer 16

• less toxic alternative procedure to chromium based oxidation
• transforms primary alcohols into aldehydes
• transforms secondary alcohols into ketones
• reagents: dess martin period inane (DMP; hypervalent iodine = breaks octet rule)

Question 17

periodic acid oxidation of glycols

Answer 17

-method for transforming a glycol into two carbonyl groups using periodic acid (HIO4)

Question 18

thiols structure

Answer 18

• contains -SH

- more p character in thiols than alcohols

Question 19

physical properties of thiols

Answer 19

-they stink
S-H bond is less polar than the O-H bond and thus exhibits much weaker H bonding
-lower boiling points for thiols than alcohols

Question 20

preparation of thiols

Answer 20

• the hydrosulfide anion is a strong nucleophile due to the polarizability of sulfur and is used to generate thiols via SN2
• thiolates are a stronger nucleophiles but weaker bases compared to alkoxides and thus prefer SN2 over E2

Question 21

acidity of thiols

Answer 21

thiols are more acidic than alcohols due to polarizability

Question 22

oxidation

Answer 22

the sulfur atoms of a thiol is easily oxidized to higher oxidation states