Organic Chemistry Exam 3

AlkEne reacted with

H2O, H2SO4

Hydration

H and OH add across double bond; Markovnikov

AlkEne reacted with

1. B2H6, diglyme

2. H2O2, HO-

Hydroboration-oxidation

H and OH add across double bond, Anti-Markovnikov

AlkEne reacted with

H2O, H2SO4

Hydration

H and OH add across double bond; Markovnikov

AlkEne reacted with

1. B2H6, diglyme

2. H2O2, HO-

Hydroboration-oxidation

H and OH add across double bond, Anti-Markovnikov

Alkyl halide reacted with

H20, Ca(OH)2, heat

Hydrolysis

OH replaces X

Grignard/organolithium reacted with formaldehyde

Primary alcohol

Grignard/organolithium reacted with aldehydes

Secondary alcohol

Grignard/organolithium reacted with ketones

Tertiary alcohol

Effect of C-C bond on oxidation state

0

Effect of C-H bond on oxidation state

-1

Effect of C-O, C-N, C-X, etc. bond on oxidation state

+1

AlkEne reacted with

H2, Pd

Hydrogenation

H2 added across double bond to form alkAne

AlkYne reacted with

H2, Pd

Hydrogenation

H2 added across double bond to form alkAne

AlkYne reacted with

H2, Lindlar Pd

Partial Hydrogenation

H2 added across double bond to form alkEne

Speed of hydrogenation of alkEnes and alkYnes

Fast

Speed of hydrogenation of aldehydes and ketones

Slow but reactive enoughSp

Speed of hydrogenation of carboxylic acids, esters, amides

No reaction

Factors affecting electrophilicity of carbonyl groups (RCOR)

Sterics and electronics

EDG (increases/decreases) electrophilicity of carbonyl

Decreases

EWG (increases/decreases) electrophilicity of carbonyl

Increases

Metal hydride examples

NaBH4 and LiAlH4

Is NaBH4 or LiALH4 a stronger reducing agent?

LiAlH4

Aldehyde reacted with

NaBH4, H2O/methanol/ethanol

Primary alcohol

Ketone reacted with
NaBH4, H2O/methanol/ethanol

Secondary alcohol

NaBH4 and LiAlH4 ability to reduce aldehydes and ketones

NaBH4 - Yes

LiAlH4 - Yes

NaBH4 and LiAlH4 ability to reduce acids, esters, amides

NaBH4 - No

LiAlH4 - Yes

Solvent for reduction via NaBH4

Aqueous, alcohol

Solvent for reduction via LiAlH4

Anhydrous, non-protic (diethyl ether, THF)

NaBH4 and LiAlH4 compatibility with acid, alcohol, water

NaBH4 - Yes

LiAlH4 - No

What is the intermediate formed during the reduction of amides by LiAlH4

Iminium ion

Iminium ion is (more/less) electrophilic than amide and reduces (fast/slow)

More; fast

Reducing agent for aldehyde → primary alcohol

LiAlH4 or NaBH3

Reducing agent for ketone → secondary alcohol

LiAlH4 or NaBH3

Reducing agent for acid → primary alcohol

LiAlH4

Reducing agent for ester → primary alcohol

LiAlH4

Reducing agent for amide → amine

LiAlH4

Reagent for epoxidation of alkEnes

peroxy acid (mCPBA)

Types of anionic nucleophiles

RLi, RMgX, R2CuLi, LiAlH4 (H-), RS-, RO-, NaCN, NaN3

When preparing alcohols from epoxides, C-Nu is (cis/trans) to C-O

Trans

Can you have an anionic nucleophile in acidic conditions?

No

Diol

2 alcohols in one molecule

AlkEne reacted with

OsO4, (CH3)3COOH, tert-butyl alcohol, HO-

Vicinal diol

During the reaction of an alkEne and OsO4, the two alcohols add to (same/different) side(s)

Same side

Acid-catalyzed condensation of an alcohol and carboxylic acid is known as __________.

Fisher esterification

Is Fisher esterification reversible?

Yes

Alcohol and acid chlorides reacted with pyridine

Esterification

Alcohol and acid anhydrides reacted with pyridine

Esterification

Primary alcohol reacted with

K2Cr2O7

H2SO4, H2O

Oxidation

Carboxylic acid

Primary alcohol reacted with

PCC (or PDC), CH2Cl2

Oxidation

Aldehyde

Secondary alcohol reacted with

K2Cr2O7

H2SO4, H2O

or

PCC (or PDC), CH2Cl2

Oxidation

Ketone

Oxidation of alcohols with DMSO-oxalyl chloride is known as __________.

Swern oxidation

Primary alcohol reacted with

1. (CH3)2S=O, (COCl)2

   CH2Cl2, -50 C

2. (CH3CH2)3N

Swern oxidation

Aldehyde

Secondary alcohol reacted with

1. (CH3)2S=O, (COCl)2

   CH2Cl2, -50 C

2. (CH3CH2)3N

Swern oxidation

Ketone

Vicinal diol reacted with HIO4

Oxidative cleavage

Ethers can form __________ complexes with metal ions.

Lewis acid/Lewis base

Crown ethers

Have multiple oxygens that can bind to a Lewis acid at multiple points

Is KF soluble in benzene

Only if 18-crown-6 is present

What happens when KF forms a complex with 18-crown-6

K+ dissolves in benzene and also carries F-, F- is unsolvated (naked)

Since F- becomes unsolvated, it can __________.

Better express anionic character

RBr reacted with

KF, ethanol

No reaction

RBr reacted with

18-crown-6

KF, benzene

RF

An important property of 18-crown-6 is its ability to

• Act as a coenzyme in biological oxidation-reduction reactions

• Oxidize primary alcohols to aldehydes

• Form a stable Lewis acid-Lewis base complex with benzene

• Form a stable Lewis acid-Lewis base complex with K+

form a stable Lewis acid-Lewis base complex with K+

Which reaction is the best candidate for catalysis by 18-crown-6?

• Bromobutane + KCN (in benzene)

• Phenol + Br2 (in water)

• Butanol + H2CrO4 (in water)

• CH3CH2CH2CHO + H2 (in ethanol)

Bromobutane + KCN (in benzene)

Reaction of RO- and R-X to form an ether is known as __________.

Williamson ether synthesis

Does Williamson ether synthesis prefer primary, secondary, or tertiary alkyl halides and why?

Primary; to avoid E2

Ethers are relatively (reactive/unreactive)

Unreactive

You should always test for __________ when working with ethers.

Peroxides

AlkEnes reacted with mCPBA

Epoxides

When synthesizing a vicinal halohydrin, H2O will attack on the (more/less) substituted carbon.

More

AlkEne reacted with

Br2, H2O

Vicinal halohydrin

Vicinal halohydrin reacted with base

Epoxide

What happens when the nucleophile attacks a vicinal halohydrin?

Stereochemistry at that carbon inverts (SN2)

For epoxidation, OH must be (anti/syn) to X

Anti

Two ways of opening epoxides

1. Reaction with anionic nucleophiles

   1. Acid catalyzed ring-opening

Why do epoxides react rapidly with anionic nucleophiles?

To relieve angle strain

Anionic nucleophiles attack epoxides at the (more/less) substituted carbon.

Less

When opening epoxides, C-Nuc is (cis/trans) to C-O

Trans

Neutral nucleophiles attack epoxides at the (more/less) substituted carbon.

More

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