Search results
Results From The WOW.Com Content Network
Most diethyl ether is produced as a byproduct of the vapor-phase hydration of ethylene to make ethanol.This process uses solid-supported phosphoric acid catalysts and can be adjusted to make more ether if the need arises: [9] Vapor-phase dehydration of ethanol over some alumina catalysts can give diethyl ether yields of up to 95%.
S N 1 ether cleavage is generally faster than S N 2 ether cleavage. However, reactions that would require the formation of unstable carbocations (methyl, vinyl, aryl or primary carbon) proceed via S N 2 mechanism. The hydrohalic acid also plays an important role, as the rate of reaction is greater with hydroiodic acid than with hydrobromic acid.
A good example is the formation of adducts between the Lewis acid borane and the oxygen atom in the Lewis bases, tetrahydrofuran (THF): BH 3 ·O(CH 2) 4 or diethyl ether: BH 3 ·O(CH 3 CH 2) 2. Many Lewis acids and Lewis bases reacting in the gas phase or in non-aqueous solvents to form adducts have been examined in the ECW model. [3]
A cyclic ether and high-boiling solvent (b.p. 101.1 °C). Tetrahydrofuran (THF) A cyclic ether, one of the most polar simple ethers that is used as a solvent. Anisole (methoxybenzene) An aryl ether and a major constituent of the essential oil of anise seed. Crown ethers: Cyclic polyethers that are used as phase transfer catalysts. Polyethylene ...
Alkenes can be made from alcohols by dehydration. This conversion, among others, is used in converting biomass to liquid fuels. [2] The conversion of ethanol to ethylene is a fundamental example: [3] [4] CH 3 CH 2 OH → H 2 C=CH 2 + H 2 O. The reaction is accelerated by acid catalysts such as sulfuric acid and certain zeolites.
The reaction mechanism of the Mitsunobu reaction is fairly complex. The identity of intermediates and the roles they play has been the subject of debate. Initially, the triphenyl phosphine (2) makes a nucleophilic attack upon diethyl azodicarboxylate (1) producing a betaine intermediate 3, which deprotonates the carboxylic acid (4) to form the ion pair 5.
Often as a solution in diethyl ether and followed by an acid workup, it will convert esters, carboxylic acids, acyl chlorides, aldehydes, and ketones into the corresponding alcohols (see: carbonyl reduction). Similarly, it converts amide, [24] [25] nitro, nitrile, imine, oxime, [26] and organic azides into the amines (see: amide reduction).
The most common solvents used are tetrahydrofuran and diethyl ether. Whatever solvent is used should be anhydrous and pure. Alkoxyaluminium hydrides should be kept as dry as possible and represent a significant fire hazard, particularly when an excess of hydride is used (hydrogen evolves during workup).