CHE-300 Review

nomenclature

syntheses

reactions

mechanisms

Alkanes

Alkyl halides

Alcohols

Ethers

Alkenes

conjugated dienes

Alkynes

Alicyclics

Epoxides

Alkanes

Nomenclature

Syntheses

1. reduction of alkene (addition of hydrogen)

2. reduction of an alkyl halide

a) hydrolysis of a Grignard reagent

b) with an active metal and acid

3. Corey-House Synthesis

Reactions

1. halogenation

2. combustion (oxidation)

3. pyrolysis (cracking)

Alkanes, nomenclature CH3

CH3CH2CH2CH2CH2CH3 CH3CHCH2CH2CH3

(n-hexane) (isohexane) n-hexane 2-methylpentane CH3 CH3

CH3CH2CHCH2CH3 CH3CCH2CH3

(no common name) CH3

3-methylpentane (neohexane)2,2-dimethylbutane

CH3

CH3CHCHCH3

CH3

(no common name)2,3-dimethylbutane

Alkanes, syntheses

1. Addition of hydrogen (reduction).

| | | |— C = C — + H2 + Ni, Pt, or Pd — C — C —

| | H H Requires catalyst.

CH3CH=CHCH3 + H2, Ni CH3CH2CH2CH3

2-butene n-butane

2. Reduction of an alkyl halide

a) hydrolysis of a Grignard reagent (two steps)

i) R—X + Mg RMgX (Grignard reagent)

ii) RMgX + H2O RH + Mg(OH)X

SB SA WA WB

CH3CH2CH2-Br + Mg CH3CH2CH2-MgBr

n-propyl bromide n-propyl magnesium bromide

CH3CH2CH2-MgBr + H2O CH3CH2CH3 + Mg(OH)Br

propane

b) with an active metal and an acid

R—X + metal/acid RH

active metals = Sn, Zn, Fe, etc.

acid = HCl, etc. (H+)

CH3CH2CHCH3 + Sn/HCl CH3CH2CH2CH3 + SnCl2

Cl sec-butyl chloride n-butane

CH3 CH3

CH3CCH3 + Zn/H+ CH3CHCH3 + ZnBr2

Brtert-butyl bromide isobutane

3. Corey-House Synthesis

CH3 CH3 CH3

CH3CH-Br + Li CH3CH-Li + CuI (CH3CH)2-CuLiisopropyl bromide

CH3 CH3

(CH3CH)2-CuLi + CH3CH2CH2-Br CH3CH-CH2CH2CH3

2-methylpentane (isohexane)

mechanism = SN2

Note: the R´X should be a 1o or methyl halide for the best yields of the final product.

Alkanes, reactions

1. Halogenation

R-H + X2, heat or hv R-X + HX

a) heat or light required for reaction.

b) X2: Cl2 > Br2 I2

c) yields mixtures

d) H: 3o > 2o > 1o > CH4

e) bromine is more selective

f) free radical substitution

CH3CH2CH2CH3 + Br2, hv CH3CH2CH2CH2-Br 2% n-butane n-butyl bromide

+CH3CH2CHCH3 98%

Br sec-butyl bromide

CH3 CH3

CH3CHCH3 + Br2, hv CH3CHCH2-Br <1% isobutane isobutyl bromide

+ CH3

CH3CCH3 99% Br tert-butyl bromide

Alkyl halides

nomenclature

syntheses

1. from alcohols

a) HX b) PX3

2. halogenation of certain alkanes

3. addition of hydrogen halides to alkenes

4. addition of halogens to alkenes

5. halide exchange for iodide

reactions

1. nucleophilic substitution

2. dehydrohalogenation

3. formation of Grignard reagent

4. reduction

Alkyl halides, nomenclature

CH3 CH3

CH3CHCH2CHCH3 CH3CCH3

Br I2-bromo-4-methylpentane tert-butyl iodide

2-iodo-2-methylpropane 2o 3o

CH3

Cl-CHCH2CH3

sec-butyl chloride2-chlorobutane 2o

Alkyl halides, syntheses

1. From alcohols

a) With HX

R-OH + HX R-X + H2O

i) HX = HCl, HBr, HI

ii) may be acid catalyzed (H+)

iii) ROH: 3o > 2o > CH3 > 1o (3o/2o – SN1; CH3/1o – SN2)

iv) rearrangements are possible except with most 1o ROH

CH3CH2CH2CH2-OH + NaBr, H2SO4, heat CH3CH2CH2CH2-Br

n-butyl alcohol (HBr) n-butyl bromide

1-butanol 1-bromobutane

CH3 CH3

CH3CCH3 + HCl CH3CCH3

OH Cl tert-butyl alcohol tert-butyl chloride 2-methyl-2-propanol 2-chloro-2-methylpropane

CH3-OH + HI, H+,heat CH3-I methyl alcohol methyl iodide methanol iodomethane

…from alcohols: b) PX3

i) PX3 = PCl3, PBr3, P + I2

ii) ROH: CH3 > 1o > 2o

iii) no rearragements

CH3CH2-OH + P, I2 CH3CH2-I

ethyl alcohol ethyl iodide

ethanol iodoethane

CH3 CH3

CH3CHCH2-OH + PBr3 CH3CHCH2-Br isobutyl alcohol isobutyl bromide

2-methyl-1-propanol 1-bromo-2-methylpropane

2. Halogenation of certain hydrocarbons.

R-H + X2, Δ or hν R-X + HX

(requires Δ or hν; Cl2 > Br2 (I2 NR); 3o>2o>1o)

yields mixtures! In syntheses, limited to those hydrocarbons that yield only one monohalogenated product.

CH3 CH3

CH3CCH3 + Cl2, heat CH3CCH2-Cl CH3 CH3

neopentane neopentyl chloride 2,2-dimethylpropane 1-chloro-2,2-dimethylpropane

5. Halide exchange for iodide.

R-X + NaI, acetone R-I + NaX

i) R-X = R-Cl or R-Br

ii) NaI is soluble in acetone, NaCl/NaBr are insoluble.

CH3CH2CH2-Br + NaI, acetone CH3CH2CH2-I

n-propyl bromide n-propyl idodide

1-bromopropane 1-idodopropane

iii) SN2 R-X should be 1o or CH3

Reactions of alkyl halides:

1. Nucleophilic substitution Best with 1o or CH3!!!!!!

R-X + :Z- R-Z + :X-

2. Dehydrohalogenation

R-X + KOH(alc) alkene(s)

3. Preparation of Grignard Reagent

R-X + Mg RMgX

4. Reduction

R-X + Mg RMgX + H2O R-H

R-X + Sn, HCl R-H

1. Nucleophilic substitution

R-X + :OH- ROH + :X- alcohol

R-X + H2O ROH + HX alcohol

R-X + :OR´- R-O-R´ + :X- ether

R-X + -:CCR´ R-CCR´ + :X- alkyne

R-X + :I- R-I + :X- iodide

R-X + :CN- R-CN + :X- nitrile

R-X + :NH3 R-NH2 + HX primary amine

R-X + :NH2R´ R-NHR´ + HX secondary amine

R-X + :SH- R-SH + :X- thiol

R-X + :SR´ R-SR´ + :X- thioether

Etc.

Best when R-X is CH3 or 1o! SN2

2. dehydrohalogenation of alkyl halides

| | | |— C — C — + KOH(alc.) — C = C — + KX + H2O | | H X

a) RX: 3o > 2o > 1o b) no rearragement c) may yield mixtures d) Saytzeff orientatione) element effectf) isotope effectg) rate = k [RX] [KOH]h) Mechanism = E2

CH3CHCH3 + KOH(alc) CH3CH=CH2

Brisopropyl bromide propylene

CH3CH2CH2CH2-Br + KOH(alc) CH3CH2CH=CH2

n-butyl bromide 1-butene

CH3CH2CHCH3 + KOH(alc) CH3CH2CH=CH2

Br 1-butene 19% sec-butyl bromide +

CH3CH=CHCH3

2-butene 81%

3. preparation of Grignard reagent

CH3CH2CH2-Br + Mg CH3CH2CH2-MgBr

n-propyl bromide n-propyl magnesium bromide

4. reduction

CH3CH2CH2-Br + Mg CH3CH2CH2-MgBr

CH3CH2CH2-MgBr + H2O CH3CH2CH3 + Mg(OH)Br

propane

CH3CH2CHCH3 + Sn/HCl CH3CH2CH2CH3 + SnCl2

Cl sec-butyl chloride n-butane

Alcohols

nomenclature

syntheses

1. oxymercuration-demercuration

2. hydroboration-oxidation

3.

4. hydrolysis of some alkyl halides

reactions

1. HX

2. PX3

3. dehydration

4. as acids

5. ester formation

6. oxidation

Alcohols, nomenclature

CH3 CH3

CH3CHCH2CHCH3 CH3CCH3

OH OH4-methyl-2-pentanol tert-butyl alcohol

2-methyl-2-propanol 2o 3o

CH3

HO-CHCH2CH3 CH3CH2CH2-OH

sec-butyl alcohol n-propyl alcohol 2-butanol 1-propanol 2o 1o

Alcohols, syntheses

1. oxymercuration-demercuration:

a) Markovnikov orientation.

b) 100% yields.

c) no rearrangements

CH3CH2CH=CH2 + H2O, Hg(OAc)2; then NaBH4

CH3CH2CHCH3

OH

2. hydroboration-oxidation:

Anti-Markovnikov orientation.

• 100% yields.

• no rearrangements

CH3CH2CH=CH2 + (BH3)2; then H2O2, NaOH

CH3CH2CH2CH2-OH

Reaction of alcohols

1. with HX:

R-OH + HX R-X + H2O

a) HX: HI > HBr > HCl

b) ROH: 3o > 2o > CH3 > 1o SN1/SN2

c) May be acid catalyzed

d) Rearrangements are possible except with most 1o alcohols.

CH3CH2CH2CH2-OH + NaBr, H2SO4, heat CH3CH2CH2CH2-Br

n-butyl alcohol (HBr) n-butyl bromide

1-butanol 1-bromobutane

CH3 CH3

CH3CCH3 + HCl CH3CCH3

OH Cl tert-butyl alcohol tert-butyl chloride 2-methyl-2-propanol 2-chloro-2-methylpropane

CH3-OH + HI, H+,heat CH3-I methyl alcohol methyl iodide methanol iodomethane

2. With PX3

ROH + PX3 RX

a) PX3 = PCl3, PBr3, P + I2

b) No rearrangements

c) ROH: CH3 > 1o > 2o

CH3 CH3

CH3CCH2-OH + PBr3 CH3CCH2-Br CH3 CH3

neopentyl alcohol 2,2-dimethyl-1-bromopropane

3. Dehydration of alcohols

| | | |— C — C — acid, heat — C = C — + H2O | | H OH

a) ROH: 3o > 2o > 1o

b) acid is a catalystc) rearrangements are possible d) mixtures are possible e) Saytzefff) mechanism is E1

CH3CH2-OH + 95% H2SO4, 170oC CH2=CH2

CH3 CH3

CH3CCH3 + 20% H2SO4, 85-90oC CH3C=CH2

OH

CH3CH2CHCH3 + 60% H2SO4, 100oC CH3CH=CHCH3

OH + CH3CH2CH=CH2

CH3CH2CH2CH2-OH + H+, 140oC CH3CH2CH=CH2

rearrangement! + CH3CH=CHCH3

4) As acids.

a) With active metals:

ROH + Na RONa + ½ H2

CH3CH2-OH + K CH3CH2-O-K+ + H2

b) With bases:

CH4 < NH3 < ROH < H2O < HF

ROH + NaOH NR!

CH3CH2OH + CH3MgBr CH4 + Mg(Oet)Br

5. Ester formation.

CH3CH2-OH + CH3CO2H, H+ CH3CO2CH2CH3 + H2O

CH3CH2-OH + CH3COCl CH3CO2CH2CH3 + HCl

CH3-OH + CH3SO2Cl CH3SO3CH3 + HCl

Esters are alkyl “salts” of acids.

6. Oxidation

Oxidizing agents: KMnO4, K2Cr2O7, CrO3, NaOCl, etc.

Primary alcohols:

CH3CH2CH2-OH + KMnO4, etc. CH3CH2CO2H

carboxylic acid

Secondary alcohols: OH O CH3CH2CHCH3 + K2Cr2O7, etc. CH3CH2CCH3

ketoneTeriary alcohols:

no reaction.

Primary alcohols ONLY can be oxidized to aldehydes:

CH3CH2CH2-OH + C5H5NHCrO3Cl CH3CH2CHO

pyridinium chlorochromate aldehyde

or

CH3CH2CH2-OH + K2Cr2O7, special conditions

Ethers

nomenclature

syntheses

1. Williamson Synthesis

2. alkoxymercuration-demercuration

reactions

1. acid cleavage

Ethers R-O-R or R-O-R´

Nomenclature:

simple ethers are named: “alkyl alkyl ether”

“dialkyl ether” if symmetric

CH3 CH3

CH3CH2-O-CH2CH3 CH3CH-O-CHCH3

diethyl ether diisopropyl ether

R-OH + Na R-O-Na+

R-O-R´

R´-OH + HX R´-X

(CH3)2CH-OH + Na (CH3)2CH-O-Na+

+ CH3CH2CH2-O-CH(CH3)2

CH3CH2CH2-OH + HBr CH3CH2CH2-Br isopropyl n-propyl ether

note: the alkyl halide is primary!

1. Williamson Synthesis of Ethers

CH3CH2CH2-OH + Na CH3CH2CH2-ONa

+ CH3CH2CH2-O-CH(CH3)2

(CH3)2CH-OH + HBr (CH3)2CH-Br

2o

The product of this attempted Williamson Synthesis using a secondary alkyl halide results not in the desired ether but in an alkene!

The alkyl halide in a Williamson Synthesis must beCH3 or 1o!

2. alkoxymercuration-demercuration:

a) Markovnikov orientation.

b) 100% yields.

c) no rearrangements

CH3CH=CH2 + CH3CHCH3, Hg(TFA)2; then NaBH4 OH

CH3 CH3

CH3CH-O-CHCH3

diisopropyl ether Avoids the elimination with 2o/3o RX in Williamson Synthesis.

Reactions, ethers:

1. Acid cleavage.

R-O-R´ + (conc) HX, heat R-X + R´-X

CH3CH2-O-CH2CH3 + HBr, heat 2 CH3CH2-Br

Alkenes

nomenclature

syntheses

1. dehydrohalogenation of an alkyl halide

2. dehydration of an alcohol

3. dehalogenation of a vicinal dihalide

4. reduction of an alkyne

reactions

1. addition of hydrogen 8. hydroboration-oxidation

2. addition of halogens 9. addition of free radicals

3. addition of hydrogen halides 10. addition of carbenes

4. addition of sulfuric acid 11. epoxidation

5. addition of water 12. hydroxylation

6. halohydrin formation 13. allylic halogenation

7. oxymercuration-demercuration 14. ozonolysis

15. vigorous oxidation

Alkenes, nomenclature

C3H6 propylene CH3CH=CH2

C4H8 butylenes CH3CH2CH=CH2

α-butylene

1-butene

CH3

CH3CH=CHCH3 CH3C=CH2

β-butylene isobutylene

2-butene 2-methylpropene

C CH

H3C CH2CH3

CH3

C CH3C

H Br

Cl

*

* *

*

(Z)-3-methyl-2-pentene

(3-methyl-cis-2-pentene)

(E)-1-bromo-1-chloropropene

1. dehydrohalogenation of alkyl halides

| | | |— C — C — + KOH(alc.) — C = C — + KX + H2O | | H X

a) RX: 3o > 2o > 1o b) no rearragement c) may yield mixtures d) Saytzeff orientatione) element effectf) isotope effectg) rate = k [RX] [KOH]h) Mechanism = E2

CH3CHCH3 + KOH(alc) CH3CH=CH2

Brisopropyl bromide propylene

CH3CH2CH2CH2-Br + KOH(alc) CH3CH2CH=CH2

n-butyl bromide 1-butene

CH3CH2CHCH3 + KOH(alc) CH3CH2CH=CH2

Br 1-butene 19% sec-butyl bromide +

CH3CH=CHCH3

2-butene 81%

2. dehydration of alcohols:

| | | |— C — C — acid, heat — C = C — + H2O | | H OH

a) ROH: 3o > 2o > 1o

b) acid is a catalystc) rearrangements are possible d) mixtures are possible e) Saytzefff) mechanism is E1

CH3CH2-OH + 95% H2SO4, 170oC CH2=CH2

CH3 CH3

CH3CCH3 + 20% H2SO4, 85-90oC CH3C=CH2

OH

CH3CH2CHCH3 + 60% H2SO4, 100oC CH3CH=CHCH3

OH + CH3CH2CH=CH2

CH3CH2CH2CH2-OH + H+, 140oC CH3CH2CH=CH2

rearrangement! + CH3CH=CHCH3

3. dehalogenation of vicinal dihalides

| | | | — C — C — + Zn — C = C — + ZnX2

| | X X

eg.CH3CH2CHCH2 + Zn CH3CH2CH=CH2 + ZnBr2

Br Br

Not generally useful as vicinal dihalides are usually made from alkenes. May be used to “protect” a carbon-carbon double bond.

CH3 H

\ /Na or Li C = C anti-

NH3(liq) / \ H CH3

trans-2-buteneCH3CCCH3

H H \ /

H2, Pd-C C = C syn- Lindlar catalyst / \ CH3 CH3

cis-2-butene

4. reduction of alkyne

Alkenes, reactions

1. Addition of hydrogen (reduction).

| | | |— C = C — + H2 + Ni, Pt, or Pd — C — C —

| | H Ha) Requires catalyst.b) #1 synthesis of alkanes

CH3CH=CHCH3 + H2, Ni CH3CH2CH2CH3

2-butene n-butane

2. Addition of halogens.

| | | |— C = C — + X2 — C — C —

| | X X

a) X2 = Br2 or Cl2

b) test for unsaturation with Br2

CH3CH2CH=CH2 + Br2/CCl4 CH3CH2CHCH2

Br Br 1-butene 1,2-dibromobutane

3. Addition of hydrogen halides. | | | |— C = C — + HX — C — C —

| | H Xa) HX = HI, HBr, HClb) Markovnikov orientation

CH3CH=CH2 + HI CH3CHCH3

I

CH3 CH3

CH2C=CH2 + HBr CH3CCH3

Br

4. Addition of sulfuric acid.

| | | |— C = C — + H2SO4 — C — C — | |

H OSO3H

alkyl hydrogen sulfate

Markovnikov orientation.

CH3CH=CH2 + H2SO4 CH3CHCH3

O O-S-O OH

5. Addition of water.

| | | |— C = C — + H2O, H+ — C — C —

| | H OHa) requires acidb) Markovnikov orientationc) low yield

CH3CH2CH=CH2 + H2O, H+ CH3CH2CHCH3

OH

6. Addition of halogens + water (halohydrin formation):

| | | |— C = C — + X2, H2O — C — C — + HX | | OH X

a) X2 = Br2, Cl2

b) Br2 = electrophile

CH3CH=CH2 + Br2(aq.) CH3CHCH2 + HBr OH Br

7. oxymercuration-demercuration:

a) Markovnikov orientation.

b) 100% yields.

c) no rearrangements

CH3CH2CH=CH2 + H2O, Hg(OAc)2; then NaBH4

CH3CH2CHCH3

OH

With alcohol instead of water:

alkoxymercuration-demercuration:

| | | |— C =C — + ROH, Hg(TFA)2 — C — C — | | OR HgTFA

| | | |— C — C — + NaBH4 — C — C — | | | | OR HgTFA OR H

ether

8. hydroboration-oxidation:

a) #2 synthesis of alcohols.

b) Anti-Markovnikov orientation.

c) 100% yields.

d) no rearrangements

CH3CH2CH=CH2 + (BH3)2; then H2O2, NaOH

CH3CH2CH2CH2-OH

9. Addition of free radicals.

| | | |— C = C — + HBr, peroxides — C — C — | |

H X

a) anti-Markovnikov orientation.b) free radical addition

CH3CH=CH2 + HBr, peroxides CH3CH2CH2-Br

10. Addition of carbenes.

| | | |— C = C — + CH2CO or CH2N2 , hν — C — C

—

CH2

•CH2• “carbene” adds across the double bond | |— C = C — •CH2•

H2C CHCH3 + CH2N2, hvHCH2C

CH2

CH3

11. Epoxidation.

| | C6H5CO3H | |

— C = C — + (peroxybenzoic acid) — C— C —

O epoxideFree radical addition of oxygen diradical. | |— C = C — •O•

H2C CHCH3

HCH2C

OCH3

PBA

12. Hydroxylation. (mild oxidation)

| | | |— C = C — + KMnO4 — C — C — syn | | OH OH

OH | | | |— C = C — + HCO3H — C — C — anti peroxyformic acid | | OH

glycol

cis-2-butene + KMnO2 meso-2,3-dihydroxybutane mp 34o

CH3

H OH

H OH

CH3

trans-2-butene + KMnO4 (S,S) & (R,R)-2,3-dihydroxybutane mp 19o

CH3 CH3

H OH + HO H

HO H H OH

CH3 CH3

stereoselective and stereospecific

C CH

H3C CH3

H

C CH

H3C H

CH3

13. Allylic halogenation.

| | | | | |— C = C — C — + X2, heat — C = C — C — + HX | | H allyl X

CH2=CHCH3 + Br2, 350oC CH2=CHCH2Br + HBr

a) X2 = Cl2 or Br2

b) or N-bromosuccinimide (NBS)

14. Ozonolysis.

| | | |— C = C — + O3; then Zn, H2O — C = O + O = C —

used for identification of alkenes

CH3

CH3CH2CH=CCH3 + O3; then Zn, H2O

CH3

CH3CH2CH=O + O=CCH3

15. Vigorous oxidation.

=CH2 + KMnO4, heat CO2

=CHR + KMnO4, heat RCOOH carboxylic acid

=CR2 + KMnO4, heat O=CR2 ketone

CH3CH2CH2CH=CH2 + KMnO4, heat

CH3CH2CH2COOH + CO2

CH3 CH3

CH3C=CHCH3 + KMnO4, heat CH3C=O + HOOCCH3

Dienes

nomenclature

syntheses

same as alkenes

reactions

same as alkenes

special: conjugated dienes

1. more stable

2. preferred products of eliminations

3. give 1,2- & 1,4- addition products

(cumulated dienes are not very stable and are rare)

isolated dienes are as you would predict, undergo addition reactions with one or two moles…

conjugated dienes are unusual in that they:

1) are more stable than predicted

2) are the preferred products of eliminations

3) give 1,2- plus 1,4-addition products

nomenclature:

CH2=CHCH=CH2 CH3CH=CHCH2CH=CHCH3

1,3-butadiene 2,5-heptadiene

conjugated isolated

2-methyl-1,3-butadiene (isoprene)

conjugated

isolated dienes: (as expected) 1,5-hexadiene

CH2=CHCH2CH2CH=CH2 + H2, Ni CH3CH2CH2CH2CH=CH2

CH2=CHCH2CH2CH=CH2 + 2 H2, Ni CH3CH2CH2CH2CH2CH3

CH2=CHCH2CH2CH=CH2 + Br2 CH2CHCH2CH2CH=CH2

Br Br

CH2=CHCH2CH2CH=CH2 + HBr CH3CHCH2CH2CH=CH2

Br

CH2=CHCH2CH2CH=CH2 + 2 HBr CH3CHCH2CH2CHCH3

Br Br

conjugated dienes yield 1,2- plus 1,4-addition:

CH2=CHCH=CH2 + H2, Ni CH3CH2CH=CH2 + CH3CH=CHCH3

CH2=CHCH=CH2 + 2 H2, Ni CH3CH2CH2CH3

CH2=CHCH=CH2 + Br2 CH2CHCH=CH2 + CH2CH=CHCH2

Br Br Br Br

CH2=CHCH=CH2 + HBr CH3CHCH=CH2 + CH3CH=CHCH2

Br Br

peroxidesCH2=CHCH=CH2 + HBr CH2CH=CHCH3 + CH2CH2CH=CH2

Br Br

Alkynes

nomenclature

syntheses

1. dehydrohalogenation of vicinal dihalides

2. coupling of metal acetylides with alkyl halides

reactions

1. reduction

2. addition of halogens

3. addition of hydrogen halides

4. addition of water

5. as acids

6. with Ag+

7. oxidation

Alkynes, nomenclature

HCCH

ethyne

acetylene

CH3

CH3CH2CCH HCCCHCH2CH3

1-butyne 3-methyl-1-pentyne

ethylacetylene sec-butylacetylene

Synthesis, alkynes:

1. dehydrohalogenation of vicinal dihalides

H H H | | |— C — C — + KOH — C = C — + KX + H2O | | | X X X

H | — C = C — + NaNH2 — C C — + NaX + NH3

| X

Synthesis of propyne from propane

CH3CH2CH3

Br2, heatCH3CH2CH2-Br + CH3CHCH3

Br

KOH(alc)

CH3CH=CH2Br2

CH3CHCH2

Br Br

KOH

CH3CH CH

Br

NaNH2CH3C CH

2. coupling of metal acetylides with 1o/CH3 alkyl halides

R-CC-Na+ + R´X R-CC-R´ + NaX

a) SN2

b) R´X must be 1o or CH3X

CH3CC-Li+ + CH3CH2-Br CH3CCCH2CH3

HCCH + 2 H2, Pt CH3CH3

[ HCCH + one mole H2, Pt CH3CH3 + CH2=CH2 + HCCH ]

H \ /

Na or Li C = C anti- NH3(liq) / \

H— C C —

\ / H2, Pd-C C = C syn-

Lindlar catalyst / \ H H

Alkyne, reactions

1. Addition of hydrogen (reduction)

CH3 H

\ /Na or Li C = C anti-

NH3(liq) / \ H CH3

trans-2-buteneCH3CCCH3

H H \ /

H2, Pd-C C = C syn- Lindlar catalyst / \ CH3 CH3

cis-2-butene

2. Addition of X2

X X X | | |— C C— + X2 — C = C — + X2 — C — C

— | | | X X X

Br Br BrCH3CCH + Br2 CH3C=CH + Br2 CH3-C-CH Br Br Br

3. Addition of hydrogen halides:

H H X | | |— C C— + HX — C = C — + HX — C — C — | | | X H X

a) HX = HI, HBr, HClb) Markovnikov orientation

ClCH3CCH + HCl CH3C=CH2 + HCl CH3CCH3

Cl Cl

4. Addition of water. Hydration.

O

— C C — + H2O, H+, HgO — CH2 — C—

H OH

— C = C —

“enol” keto-enol tautomerism

Markovnikov orientation.

CH3CH2CCH + H2O, H2SO4, HgO

1-butyne

O

CH3CH2CCH3

2-butanone

5. As acids. terminal alkynes only!

a) with active metals

CH3CCH + Na CH3CC-Na+ + ½ H2

b) with bases CH4 < NH3 < HCCH < ROH < H2O < HF

CH3CCH + CH3MgBr CH4 + CH3C CMgBr

SA SB WA WB

6. Ag+ terminal alkynes only!

CH3CH2CCH + AgNO3 CH3CH2CC-Ag+

CH3CCCH3 + AgNO3 NR (not terminal)

formation of a precipitate is a test for terminal alkynes.

CH3CH2CCCH3 + KMnO4

CH3CCH + hot KMnO4

CH3CCCH3 + O3; then Zn, H2O

CH3CH2COOH + HOOCCH3

CH3COOH + CO2

2 CH3COOH

7. Oxidation

Alicyclics

nomenclature

syntheses

like alkanes, alkenes, alcohols, etc.

reactions

as expected

exceptions: cyclopropane/cyclobutane

CH3

BrBr Br Br

CH3

H3C

methylcyclopentane 1,1-dimethylcyclobutane

trans-1,2-dibromocyclohexane

Br

Br

cyclopentene 3-methylcyclohexene 1,3-cyclobutadiene

1

2

3

4

5

6

Cycloalkanes, syntheses

A. Modification of a cyclic compound:

Br

Br

H2, Ni

Sn, HCl

Mg; then H2O

Cycloalkanes, reactions:

1. halogenation

2. combustion

3. cracking

4. exceptions

ClCl2, heat

+ HCl

exceptions:

H2, Ni, 80o

CH3CH2CH3

Cl2, FeCl3

Cl-CH2CH2CH2-Cl

H2O, H+

CH3CH2CH2-OH

conc. H2SO4

CH3CH2CH2-OSO3H

HI CH3CH2CH2-I

exceptions (cont.)

+ H2, Ni, 200o CH3CH2CH2CH3

OH

Br

Br

Cl KOH(alc)

H+, Δ

Zn

cyclohexene

Cycloalkenes, syntheses

Cycloalkenes, reactions:

1. addition of H2 8. hydroboration-oxid.

2. addition of X2 9. addition of free radicals

3. addition of HX 10. addition of carbenes

4. addition of H2SO4 11. epoxidation

5. addition of H2O,H+ 12. hydroxylation

6. addition of X2 + H2O 13. allylic halogenation

7. oxymerc-demerc. 14. ozonolysis

15. vigorous oxidation

Br

Br

Br

OSO3H

OH

OH

Br

+

H2, Pt

Br2, CCl4

HBr

H2SO4

H2O, H+

Br2 (aq.)

dimerization

trans-1,2-dibromocyclohexane

Markovnikov

n

OH

OH

Br

+

O

HF

H2O,Hg(OAc)2 NaBH4

(BH3)2 H2O2, NaOH

HBr, perox.

polymer.

CH2CO,hv

PBA

Markovnikov

anti-Markovnikov

anti-Markovinikov

OH

OH

OH

OH

Br

KMnO4

HCO3H

Br2, heat

O3 Zn, H2O

KMnO4, heat

O=CHCH2CH2CH2CH2CH=O

HO2CCH2CH2CH2CH2CO2H

cis-1,2-cylohexanediol

trans-1,2-cyclohexanediol

Epoxides

nomenclature

syntheses

1. epoxidation of alkenes

reactions

1. addition of acids

2. addition of bases

Epoxides, nomenclature

CH2H2CO

HCH2C

OCH3 O

O

ethylene oxide propylene oxide cyclopentene oxide

(oxirane) (methyloxirane)

C6H5CO3H

Synthesis:

β-butylene oxidecis-2-butene

epoxides, reactions:

1) acid catalyzed addition

CH2H2CO

CH2H2CO

CH2H2CO

H2O, H+

CH3CH2OH, H+

HBr

OHCH2CH2

OH

OHCH3CH2-O-CH2CH2

OHCH2CH2

Br

CH2H2CO

CH2H2CO

CH2H2CO

CH2H2CO

NaOH, H2O

NaOCH2CH3

CH3CH2OH

NH3

1. CH3CH2MgBr

2. H2O

OHCH2CH2

OH

CH3CH2-O-CH2CH2-OH

H2N-CH2CH2-OH

CH3CH2CH2CH2-OH

2. Base catalyzed addition

Mechanisms:

Free radical substitution

SN2

SN1

E2

E1

ionic electrophilic addition

free radical electrophilic addition

Memorize (all steps, curved arrow formalism, RDS) and know which reactions go by these mechanisms!

Free Radical Substitution Mechanism

initiating step:

1) X—X 2 X•

propagating steps:

2) X• + R—H H—X + R•

3) R• + X—X R—X + X•

2), 3), 2), 3)…

terminating steps:

4) 2 X• X—X

5) R• + X• R—X

6) 2 R• R—R

Substitution, nucleophilic, bimolecular (SN2)

CH3 > 1o > 2o > 3o

SN2

Z: + C W Z C + :WRDS

Substitution, nucleophilic, unimolecular (SN1)

3o > 2o > 1o > CH3

C WRDS

C + :W

C + :Z C Z

carbocation

1)

2)

Mechanism = elimination, bimolecular E2

3o > 2o > 1o

base:

C

W

C

H

C C + H:base + :WRDS

C C

H W

RDSC C

H

1) + :W

2) C C

H

- HC C

Elimination, unimolecular E1

3o > 2o > 1o

Ionic electrophilic addition mechanism

1) C C + YZRDS

C C

Y

+ Z

2) C C + Z C C

YZY

Free radical electrophilic addition of HBr:

Initiating steps:

1) peroxide 2 radical•

2) radical• + HBr radical:H + Br• (Br• electrophile)

Propagating steps:

3) Br• + CH3CH=CH2 CH3CHCH2-Br (2o free radical) •4) CH3CHCH2-Br + HBr CH3CH2CH2-Br + Br• •

3), 4), 3), 4)…

Terminating steps:

5) Br• + Br• Br2

Etc.