Alkyl reactions with strong acids

REACTIONS OF ALKYL CHLORIDES WITH STRONG ACIDS... 

Alcohols can be dehydrated with strong acid catalysts and high reaction temperatures to produce ethers. This method is particularly useful for the preparation of symmetrical lower alkyl ethers, such as ethyl ether. 

Kinetic and thermodynamic parameters have been measured for the chlorination of simple aliphatic and aryl alkyl ketones in strong acid media by chloramine-B (sodium A-chlorobenzenesulfonamide). Catalysis of the monochlorination of acetaldehyde in anhydrous carbon tetrachloride by trichloroacetic acid, and by hydrogen chloride, are reported. IR and UV spectroscopy have been used to probe the reaction of acetaldehyde with trichloroacetic acid in carbon tetrachloride. " Two cyclic 1 1 intermediates have been identified, and are found to be in equilibrium. 

Only a few reactions of imidazo[2,l-h][l,3,4]oxadiazoles have been reported. The basicity of these compounds is rather low hydrohalides cannot be isolated (69ZC337). Protonation of 23 with strong acids occurs at position 7, giving, for example, 24 (mp 212°C with explosion ). With aqueous base 24 is converted back to 23 (72BSF3968). On alkylation of 23 the quaternary salts 25 are obtained (72BSF3968). Reaction of 25 (R = Et) with ethyl cyanoacetate (Et3N/EtOH) yields 26, albeit in low yield (3.8%) (72BSF3968). 

Typical electrophilic reactions, such as nitration, halogenation with a Lewis acid (as a carrier ), Friedel-Crafts C-alkylation and -acylation, that work well with benzene, cannot be applied to pyrrole, because heating with strong acids, or a Lewis acid, destroys the heterocycle. However,... 

Triphenylmethyl acetate67-84 and benzoate75 are solvolyzed with alkyl-oxygen fission even under neutral conditions, and the reaction is strongly acid-catalyzed in each case. The hydrolysis of triphenylmethyl acetate in 80% dioxan-water has been studied by Bunton and Konasiewicz 7. The reaction involves near-quantitative alkyl-oxygen fission in both acidic and initially neutral solution, as shown by the incorporation of l80 from enriched H20 into the triphenylmethyl alcohol produced, and by the lack of incorporation into the acetic acid. The rate of the acid-catalyzed reaction at 25°C is about 40% slower in 90% dioxan than in the more aqueous solvent. ... 

Due to the lability of the alkyl-oxygen bond in alkyl cyanates, the direct trimerization reaction to 2,4.6-trialkoxy-l,3,5-triazines runs into difficulties. Often side reactions, such as isomerization to isocyanates (Lewis acid catalysis)242 or alkylation reactions with nucleophilic catalysts or anions,243 are observed. Steric hindrance or strongly electron-accepting substituents enhance the stability of alkyl cyanates in these cases selective trimerization to the corresponding... 

Alkylation occurs at sulfm 22,104). jbe reaction with Hg(OAc)2 and with strong acids n) probably starts by attack at the sulfur center. 

Good yields of 5-oxo-l,3-oxazines (212) have been obtained by treatment of the diazo-ketones (211) with strong acid. The reaction of jV-alkyl-cyanamides (RNHCN) with diketen gives oxazin-4-ones (213), which may be transformed into uracils (214) by refluxing in acetic acid. ... 

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