Search results
Results From The WOW.Com Content Network
Alcohol oxidation is a collection of oxidation reactions in organic chemistry that convert alcohols to aldehydes, ketones, carboxylic acids, and esters. The reaction mainly applies to primary and secondary alcohols. Secondary alcohols form ketones, while primary alcohols form aldehydes or carboxylic acids. [1] A variety of oxidants can be used.
The sulfuric acid must be added dropwise or the reaction must be actively cooled because the reaction itself is highly exothermic. CH 3 CH 2 OH + H 2 SO 4 → CH 3 CH 2 OSO 3 H + H 2 O. If the temperature exceeds 140 °C, the ethyl sulfate product tends to react with residual ethanol starting material, producing diethyl ether.
Due to the strongly alkaline reaction conditions, aldehydes that have alpha hydrogen atom(s) instead undergo deprotonation there, leading to enolates and possible aldol reactions. Under ideal conditions the reaction produces 50% of both the alcohol and the carboxylic acid (it takes two aldehydes to produce one acid and one alcohol). [5]
Esters react in the presence of an acid or base to give back the alcohol and a salt. This reaction is known as saponification because it is used in the preparation of soap. Ethanol can also form esters with inorganic acids. Diethyl sulfate and triethyl phosphate are prepared by treating ethanol with sulfur trioxide and phosphorus pentoxide ...
In terms of reaction mechanism, metal hydrides effect nucleophilic addition of hydride to the carbonyl carbon. The ease of addition of hydride to the carbonyl is affected by electrophilicity and bulk of the carbonyl as well as the corresponding electronic and steric properties of the hydride reagent.
The reaction mechanism [5] begins with the protonation of the alcohol which leaves in an E1 reaction to form the allene from the alkyne. Attack of a water molecule on the carbocation and deprotonation is followed by tautomerization to give the α,β-unsaturated carbonyl compound. Edens et al. have investigated the reaction mechanism. [6]
The reaction usually requires a catalyst, such as concentrated sulfuric acid: R−OH + R'−CO 2 H → R'−CO 2 R + H 2 O. Other types of ester are prepared in a similar manner−for example, tosyl (tosylate) esters are made by reaction of the alcohol with 4-toluenesulfonyl chloride in pyridine.
Ether cleavage refers to chemical substitution reactions that lead to the cleavage of ethers. Due to the high chemical stability of ethers, the cleavage of the C-O bond is uncommon in the absence of specialized reagents or under extreme conditions. [1] [2] In organic chemistry, ether cleavage is an acid catalyzed nucleophilic substitution reaction.