CHEM 2312 Exam 2 Adsila Reagent cards

LiAlH4

Lithium aluminum hydride is a very strong reducing agent. It will reduce aldehydes, ketones, esters, and carboxylic acids to alcohols, and amides and nitriles to amines. It will also open epoxides.

NaBH4

Sodium borohydride is a mild reducing agent for the reduction of ketones and aldehydes, it will also reduce acid halides. It is used in the oxymercuration reaction to replace mercury with H.

PCC, CH2Cl2

A mild oxidizing agent that will oxidize a primary alcohol to give an aldehyde, rather than a carboxylic acid. Secondary alcohols are oxidized to give ketones.

Na2Cr2O7, H2SO4, H2O

A mixture of sodium dichromate and sulfuric acid gives chromic acid, which is a strong oxidizing agent. Primary alcohols are oxidized to give carboxylic acids, while secondary alcohols are oxidized to give ketones. Tertiary alcohols are generally unreactive.

Wittig Reaction

*converts a ketone to an alkene.

*phosphorous ylide used.

*the ketone first undergoes nucleophilic addition from the ylide to form a betaine.

*the betaine is unstable and quickly breaks down to a triphenylphosphine oxide and the alkene.

Grignard Reaction

Synthesize an alcohol from an ether with R-MgX in acid via nucleophilic attack on the carbonyl carbon. Also works on C＝O, C≣N, S＝O, N＝O.

Nucleophilic Acyl Substitution

Reaction where a nucleophile attacks an acyl carbonyl and a leaving group is expelled

Baeyer-Villiger Oxidation

*Oxidizes ketone to ester

*mcPBA (peroxyacid) /Ch2Cl2

*Carboxylic acid is a side product

Examples of carbon nucleophiles

RMgX

RLi

R2CuLi

R-C=-C-+Na

Examples of oxygen nucleophiles

H2O

RCOO-

OH-

etc

General Mechanism of Nucleophilic Acyl Substitution

Nucleophile attacks carbonyl → tetrahedral intermediate forms → leaving group leaves → carbonyl reforms

Driving Force of Nucleophilic Acyl Substitution

Expulsion of the best leaving group (weakest base)

Common Nucleophiles in Acyl Substitution

RO⁻, HO⁻, H₂O, NH₃, RNH₂

Common Leaving Groups in Acyl Substitution

Cl⁻, RCOO⁻, RO⁻, NH₂⁻

Reactivity Order of Carboxylic Acid Derivatives

Acid chloride > Anhydride > Ester > Amide

Acid Chloride Hydrolysis

Acid chloride + H₂O → carboxylic acid

Ester Hydrolysis (Acidic)

Ester + H₂O + H⁺ → carboxylic acid + alcohol

Saponification

Base hydrolysis of an ester forming carboxylate + alcohol

Fischer Esterification

Carboxylic acid + alcohol + H⁺ → ester + water

Transesterification

Exchange of the alkoxy group of an ester using another alcohol.

Carbonyls That Undergo Addition

Aldehydes and ketones