Alkyl chlorides synthesis from alcohols

Olefin synthesis from alcohols. Primary and secondary alcohols containing a /3-hydrogen can be converted into olefins by conversion into the alkoxide (sodium hydride, DMF) and then reaction of the alkoxide with N,N-dimethylthiocarbamoyl chloride to form an O-alkyl dimethylthiocarbamate. These derivatives on heating to 180-200° for 2 hours decompose to form olefins. The other product is dimethylammonium dimethylthiocarbamate (2). The complete sequence is formulated as follows ... 

Synthesis.—The radical anion from di-t-butylbiphenyl is found to be superior to lithium naphthalene for the reductive removal of halogen from alkyl chlorides (Table la). Alcohols are reduced directly to the corresponding hydrocarbon by the addition of a silane R3SiH to the alcohol in methylene chloride followed by... 

Both reactants m the Williamson ether synthesis usually originate m alcohol pre cursors Sodium and potassium alkoxides are prepared by reaction of an alcohol with the appropriate metal and alkyl halides are most commonly made from alcohols by reaction with a hydrogen halide (Section 4 7) thionyl chloride (Section 4 13) or phosphorus tri bromide (Section 4 13) Alternatively alkyl p toluenesulfonates may be used m place of alkyl halides alkyl p toluenesulfonates are also prepared from alcohols as their imme diate precursors (Section 8 14)... 

A considerable amount of hydrobromic acid is consumed in the manufacture of inorganic bromides, as well as in the synthesis of alkyl bromides from alcohols. The acid can also be used to hydrobrominate olefins (qv). The addition can take place by an ionic mechanism, usually in a polar solvent, according to Markownikoff s rule to yield a secondary alkyl bromide. Under the influence of a free-radical catalyst, in aprotic, nonpolar solvents, dry hydrogen bromide reacts with an a-olefin to produce a primary alkyl bromide as the predominant product. Primary alkyl bromides are useful in synthesizing other compounds and are 40—60 times as reactive as the corresponding chlorides (6). 

Aldono-1,5-lactones and free aldonic acids react with alcohols in the presence of hydrogen chloride to give the corresponding alkyl aldonates (84). The reaction is slower with 1,4-lactones. Because esterification takes place very slowly in the absence of an acidic catalyst, aldonic acids and their lactones may be recrystallized from boiling alcohols without appreciable esterification (85). However, in some instances, alkyl esters are formed under these conditions. For example, essentially pure ethyl L-mannonate was isolated (6.4% yield) from the mother liquors of crystallization L-man-nono-1,4-lactone, obtained by Kiliani synthesis from L-arabinose (86). Similarly, repeated recrystallization from ethanol of crude 2,3,4,6-tetra-O-acetyl-D-glucono- 1,5-lactone afforded the corresponding ethyl gluconate derivative (87). 

Reaction XLIII. (a) Formation of Esters by the action of Acid Anhydrides or of Acid Chlorides on an Alcohol in the presence of Magnesium Alkyl Halide (Grignard). (B., 39, 1738.)—This application of the Grig-nard reaction to the preparation of esters is of theoretical rather than practical interest as illustrating the wide applicability of this many-sided reaction. The steps in the synthesis will be clear from the examples given they are somewhat different from the usual phases of a Grignard reaction. 

Williamson synthesis of phenyl alkyl and dialkyl ethers. Phenols react with alkyl halides in 20% aqueous NaOH containing 1 equiv. of this surfactant at 80° to form phenolic ethers in 85-97% yield. There is no reaction in the absence of CTAB. This procedure is not useful for preparation of dialkyl ethers from alcohols and alkyl halides. Instead, the alkyl chloride, alcohol, a trace of water, and CTAB are heated in THF at 70° with NaOH (2 equiv.). 

In a similar fashion, chromium tricarbonyl complexes of aryl ketones are exclusively alkylated and reduced from the exo face relative to the metal. For example, addition of vinyl magnesium chloride to the substituted tetralone complex (42) affords the alcohol (43) exclusively with an antirelationship between the incoming nucleophile and the chromium tricarbonyl group (Scheme 83). This was used in a synthesis of 11-epi-helioporin B. 2-Trimethylsilyl-substituted benzaldehyde complexes undergo an interesting... 

Williamson ether synthesis. A German patent9 noted that ethers could be prepared from an alcohol, sodium hydroxide, and an alkyl chloride (the Williamson synthesis ordinarily involves the use of sodium metal). Canadian chemists10 have confirmed this observation and found further that the reaction time is decreased... 

Condensations. The transformation of acid chlorides to anhydrides by (Ph3P)2CoCl2 and the direct synthesis of unsymmetrical carbonic esters from alcohols, CO2, and alkyl halides by solid-liquid phase-transfer reactions are most expedient. 

Unsaturated hydrocarbons are readily prepared from ketonet and alkyl chlorides by Grignard s synthesis. The reaction first yields a tertiary alcohol, which at a higher temperature loses water and passes into a hydrocarbon. Diphenyl ketone, for example, gives with magnesium methyl iodide diphenylethylene —... 

A new synthesis of alkyl chlorides consists of the interaction of 2-alkoxy-3-ethylbenzoxazolium salts (54a), formed in situ from alcohols and a 2-chloro-3-ethylbenzoxazolium salt (Scheme 32), with tetraethylammonium chloride. This... 

A mixture of octanol, a little hexadecyltrimethylammonium bromide, and 37% aq. HCl heated at reflux overnight 1-chlorooctane. Y 87% (Y 47% in the absence of micelles). Solubility of alcohols in coned, aq. HCl is considerably enhanced in micellar media, thereby effecting an inexpensive conversion to alkyl chlorides in high yield. F.e.s. B. Jursic, Synthesis 1988, 868-71 halogenative cleavage of ethers, inch dichlorides from cyclic ethers, and phenols and alkyl chlorides from phenolethers, s. J. Chem. Res. (S) 1989, 284 5. 

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