Au Organic Chem Exam 2

Front 1

What is special about E2 reactions in cyclohexanes

Back 1

requires leaving groups be axial

Front 2

For each class of alkyl halide, list the factors in SN1 vs. E1

Back 2

Primary - cannot undergo

Secondary - Both

Tertiary - Both but figure shows more SN1 (this is good since no SN2)

Front 3

For each class of alkyl halide list the factors in SN2 vs. E2

Back 3

Primary - mostly substitution unless there is steric hindrance in the alkyl halide or base then elimination is favored

Secondary - both, the stronger and bulkier the base, the higher the temp, the more elimination

Tertiary - only elimination

Front 4

2 ether cleavage pathways

Back 4

ethers are cleaved by an SN1 (nucleophile goes with carbocation) pathway unless the instability of the carbocation requires SN2 (the nucleophile goes with less sterically hindered carbon)

Front 5

What does chromic acid (H2CrO4) do to primary etoh

Back 5

oxidize twice, first to aldehyde then to carboxylic acid

Front 6

2 types of halides that can undergo SN2 and SN1

Back 6

benzyllic and allylic

Front 7

2 types of halides that cannot undergo SN2 and SN1

Back 7

vinylic and arylic

Front 8

3 things that affect SN2

Back 8

leaving group - weaker base better leaving group

nucleophile - stronger base, better nuclophile

solvent - aprotic favors more basic nucleophiles, protic favors less basic nucleophiles

Front 9

2 polar protic solvents

Back 9

H2O, mtoh

Front 10

2 polar aprotic solvents

Back 10

DMSO, DMF

Front 11

In terms of stereochemistry, SN2 proceeds with complete _________ and SN1 proceeds with complete ______.

Back 11

inversion, racemization

Front 12

3 factors that affect SN2 vs SN1

Back 12

Nucleophile concentration, nucleophile reactivity, solvent

Front 13

How does polarity of the solvent affect SN1

Back 13

more polar means faster since the charged intermediate is stablized

Front 14

intermolecular vs. intramolecular, what two factors affect which reaction is dominant.

Back 14

High concentration of the molecule increases intermolecular and size of the ring formed (3 above 4, 5 and 6 above everything else)

Front 15

3 exceptions to zaitzev's rule

Back 15

bulky bases that cannot reach the more substituted beta carbon

conjugated alkenes

fluorine leaving groups - transition state is more like a carbanion which is more stable as primary

Front 16

2 factors in E2 vs E1

Back 16

primary alkylhalides can only undergo E2

with sec and tert, E2 is favored with high conc. of strong base in aprotic polar solvent

Front 17

4 factors affecting SN2/E2 competition

Back 17

steric hindrance of a.h. or base favors elimination

strong base favors elimination

high temp favors elimination

tert-alkylhalide favors elimination

Front 18

important thing to remember in williamson ether synthesis

Back 18

less hindered group should be provided by the alkyl halide

Front 19

How do alcohols react

Back 19

Sec and tert by SN1, primary by SN2

Front 20

What does HCl require to react with etoh

Back 20

ZnCl2

Front 21

2 addtional methods for converting etoh to a.h.

Back 21

phosphorous tribromide(or chloride), thonyl chloride

Front 22

alternatives to a.h. for leaving groups from etoh

Back 22

sulfontate ester, tosylate

TsCl in pyradine

Front 23

how are alcohols dehydrated

Back 23

with phosporic or sulfuric acid

sec. tert by E1, primary by E2

Front 24

dehydration under milder conditions

Back 24

POCl3 (phosphorous oxychloride) pyridine, 0 degrees

Front 25

how do you make ketones from alcohol

Back 25

you need a secondary alcohol and chromic acid

Front 26

how do you make carboxylic acid from alcohol

Back 26

primary alcohol oxidized twice by chromic acid

Front 27

how do you make an aldehyde from alcohol

Back 27

single oxidation of a primary alcohol by PCC/CH2Cl2

Front 28

what happens when you oxidize tertiary alcohols

Back 28

nothing there is no hydrogen to take

Front 29

describe how ethers react with hydrogen halides

Back 29

By SN1 when a secondary or tertiary carbocation can form. Otherwise by SN2 where the nucleophile attacks the less sterically hindered carbon

Front 30

how are griniard reagents made

Back 30

Mg/diethylether or THF

Front 31

Two components of a diels alder reaction.

Back 31

diene and dienophile

Front 32

draw the following: bromobenzene, chlorobenzene, nitrobenzene, ethylbenzene, toluene, phenol, aniline, benzenesulfonic acid, anisole, styrene, benzaldehyde, benzoic acid, benzonitrile, isopropylbenzene, sec-butylbenzene, tert-butylbenzene, 2-phenylbenzene, 3-phenylbenzene

Back 32

last page of Lec. 20

Front 33

describe what is needed for halogenation of benzene

Back 33

Br2/FeBr3 (or Cl), lewis acid catalyst, the Fe pulls on the Br2 while the benzene attacks the Br

Front 34

describe what is needed for nitration of benzene (nitrobenzene)

Back 34

H2SO4 generates nitronium ion (NO2+) from nitric acid (HNO3) by adding a proton and water falls off

Front 35

describe what is needed for the sulfoniation of benzene (benzenesulfonic acid)

Back 35

H2SO4 and heat, one of the sulfuric acids adds a proton to the other and a water falls off leaving a sulfonium that is open to attack

Front 36

describe what is used in friedel crafts acylation

Back 36

a benzene with an acyl chloride and AlCl3/H20, this pops off the chloride the positively charged acylium ion then is open to attack by electrophilic aromatic substitution

Front 37

describe what is used in a friedel crafts alkylation

Back 37

benzene and 1-chlorobutane with AlCl3 at zero degrees, this pops off the chlorine and makes a primary carbocation which is open to attach by electrophilic aromatic substitution

Front 38

How can you insert a bromine at the benzylic position of an alkylbenzene

Back 38

with NBS heat and peroxide