Hydrogen halides industrial synthesis

When applied to the synthesis of ethers the reaction is effective only with primary alcohols Elimination to form alkenes predominates with secondary and tertiary alcohols Diethyl ether is prepared on an industrial scale by heating ethanol with sulfuric acid at 140°C At higher temperatures elimination predominates and ethylene is the major product A mechanism for the formation of diethyl ether is outlined m Figure 15 3 The individual steps of this mechanism are analogous to those seen earlier Nucleophilic attack on a protonated alcohol was encountered m the reaction of primary alcohols with hydrogen halides (Section 4 12) and the nucleophilic properties of alcohols were dis cussed m the context of solvolysis reactions (Section 8 7) Both the first and the last steps are proton transfer reactions between oxygens... 

Elimination of hydrogen halide from haloalkanes to produce alkenes is an important process in organic synthesis and industry. Realization of this reaction under PTC conditions requires continuous transfer of base (OH anions) into the organic phase ... 

Elimination of hydrogen halides from haloalkanes and haloalkenes is an important process of synthesis of alkenes and alkynes, widely used in laboratories and industry. It is usually executed via action of strong bases NaOH, KOH, alkoxides, or trialkylamines on haloalkanes in homogeneous media. 

Aliphatic Ethers. The aliphatic ethers used in industry are made usually by the action of sulfuric acid on an alcohol. Ethyl ether and isopropyl ether are thus prepared. However, more ethyl ether than the market usually absorbs is obtained as a by-product of the hydration of ethylene to alcohol. Alkyl halides react on a hydroxyl group either directly, in the presence of an alkali, or after the hydrogen of a hydroxyl group has been replaced by sodium. This is the Williamson synthesis which is particularly applicable to making mixed ethers ... 

The units 49 and 50 used in the synthesis of vitamin A are also used in many ways in carotenoid syntheses and are produced industrially in large scale. p-Ionone (17) can be converted into vinyl-p-ionol (51) by ethynylation to 52 and partial hydrogenation [42]. This conversion is also achieved in one step by 1,2-addition of vinylmagnesium chloride 55[43]. The two routes are, in principle, equivalent, and which one is used in practice is decided by conditions on site. In this example, the main considerations are the availability of acetylene (4) and vinyl chloride, operating experience, and permits for handling these materials. The Ci5-phosphonium salt 49 is formed directly from 51 by the action of triphenylphosphine and acid [44,45]. A step involving labile P-ionylidene-ethyl halide is thus avoided. Crystalline (lE,9E)-49 is obtained in excellent yield by reaction of 51 with triphenylphosphine and sulphuric acid in isopropanol/heptane [46]. 

The electrochemical coupling of chlorosilanes with organic halides appears to be an attractive pathway for the synthesis of organosilicon compounds. Regarding industrial applications, the use of our specially developed hydrogen anode [1] is of particular interest, as it produces HCl instead of metal salts. Thus, starting from a work of Bordeau et al. on the trimethylsilylation of o-dichlorobenzene [2], we tested the applicability of electrochemical reduction for the synthesis of phenylated and /-butyl-substituted silanes. 

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