Reaction Reagents 8

Question 1

alcohols have – BP?

Answer 1

much higher BP bc it can do HB with O or H

Question 2

alcohols are

Answer 2

amphoteric! act as base or acid

Question 3

making alkoxide reaction

Answer 3

alcohol gets deprotonated by strong acid (NaH) or becomes salt with metal (Na, K, Li)

H- of NaH acts as base and removes H from OH of alcohol making alkoxide

Question 4

Factors that stabilize alcohols and phenols?

Answer 4

1. resonance: phenol + benzene + OH
2. induction: add EWG to OH
3. solvation effects: less sterically hindered = can solvate and stabilize charge better = stronger acid

Question 5

alcohol synthesis from alkyl halide

Answer 5

substitution:

primary alkyl halide + strong nuc/base -> alcohol (Sn2)

tertiary alkyl halide + weak base -> alcohol (Sn1)

Question 6

alcohol synthesis from alkenes

Answer 6

addition rxns

ACID CATALYZED HYDRATION
alkene pi attacks H on H3O, makes carbocation, carbocation gets attacked by H2O, gets deprotonated (OH ends up on most subbed C)

HYDROBORATION OXIDATION
alkene attacks B on BH3, and BH2 adds to least hindered group, H2O2 + NaOH substitutes BH2 (OH ends up on least subbed C)

DIOLS
syn: OsO4/KMnO4
anti: peroxyacid - 1)RCO3H, 2)H3O+

Question 7

How can you determine oxidation state of C?

Answer 7

treat bonds as ionic and count a neg charge to most EN atom in bond

Question 8

What is the general mechanism of reduction to make alcohols?

Answer 8

carbonyl group has pi bond, C in pi bond gets attacked, other group adds to C and O on carbonyl gets protonated

Question 9

catalytic hydrogenation reaction to make alcohol

Answer 9

carbonyl + H2 + metal catalyst (Pt, Pd, Ni)
adds H to C and O turns to OH, pi bond becomes single bond

this is not selective; all pi bonds get H’s added

Question 10

carbonyl + NaBH4 (sodium borohydride)

Answer 10

H of BH4 attacks C of C=O -> puts H on to carbonyl C

O- of carbonyl intermediate attacks proton donor (H2O, EtOH, MeOH) to protonate O

makes alcohol
**
unsymmetrical ketone or aldehyde gets attacked by H- on either side = enantiomers**

NaBH4 is a common reducing agent for aldehydes and ketones

Question 11

carbonyl + LiAlH4 (lithium aluminum hydride)

Answer 11

H of AlH4 acts as H-, adds C to C=O of carbonyl

second step: proton donor for O- to become OH

alcohol formation

Question 12

How does NaBH4 compare to LAH?

Answer 12

LAH stronger bc Al is less EN than B so more polarized bond of H-Al

Question 13

What can LAH reduce that NaBH4 can’t?

Answer 13

esters and carboxylic acids ==> makes primary alcohols

Question 14

ester + LAH

Answer 14

1. H of LAH attacks C of C=O
2. single bonded O (and its group) (alkoxide) LG
3. double bond C=O reforms
4. H of LAH attacks C of C=O again
5. O- from carbonyl basic attack on proton donor

makes primary alcohol

Question 15

alkyl halide + Mg metal

Answer 15

R-Mg-X = C-

C- = really good nucleophile = strong base

can’t be made in presence of proton source

Question 16

carbonyl + grignard

Answer 16

1. grignard C- attacks C on C=O forming new C-C bond
2. O- on carbonyl basic attack a proton source

makes alcohol

reacts with ester, aryl, aldehyde, or ketone

Question 17

how can grignard react when the alkyl halide has an acidic H?

ex making a diol from an alcohol

Answer 17

1. protect alcohol with trimethylsilyl (TMS-Cl) and Et3N
2. removes acidic H and now have TMS (or OTMS if alcohol to start)
3. react was Mg to make grignard C-
4. react with carbonyl group
5. protonate alkoxide of carbonyl group with water
6. add fluoride (TBAF) to deprotect

Question 18

alcohol + HCl + ZnCl2

Answer 18

1. OH nuc attack on ZnCl2 (lewis acid)
2. ZnCl2 makes OH better LG
3. Cl- attacks C that was C-OH and OHZnCl2 leaves
4. make alkyl chloride

Question 19

alcohol + 1) TsCl + py +2? NaBr

Answer 19

1. TsCl, py converts OH into OTs (good LG)
2. Br- (or other halide) substitution rxn
3. makes alkyl halide

Question 20

1º or 2º alcohol + SOCl2, py

Answer 20

1. O of OH attacks S on SOCl2, making good LG
2. Cl- leaves and then attacks C- that has SO2Cl which leaves
3. makes alkyl chlorine

chlorination of alcohol

Question 21

1º or 2º alcohol + PBr3

Answer 21

1. OH O attacks P, Br- leaves
2. Br- attacks C that is attached to PBr2, OHPBr2 leaves
3. alkyl bromide made

bromination

Question 22

oxidation of 1º alcohol

Answer 22

aldehyde -> carboxylic acid

Question 23

2º alcohol oxidation

Answer 23

ketone

Question 24

3º alcohol oxidation

Answer 24

no rxn (no H on alpha C)