Nitrile-Hydrogen Halide Systems

A scharfe Knick der Kurve at the 1 1 ratio was taken to indicate the formation of the monohydrohalide. But experiments with benzonitrile throw doubt on the validity 

PhCH2CN, HBr, PhCH=CHCN, HBr, although it was not clear how he prepared these. 

Hinkel and Treharne (1945) did not refer to Hantzsch s observation and stated that hydrogen chloride readily combines with acetonitrile at low temperatures (ice-salt) to form the crystalline acetamide dichloride MeCCl2NH2, mp 6°C, although it was stated that at 40 C/11 mm the solid dichloride lost its crystalline structure. At ordinary temperatures methyl cyanide, acetamide chloride [CH3C(C1)=NH], and hydrogen chloride were obtained, but there was no stated evidence for the existence of the monochloride. 

Janz and Danyluk (1959) described their conductance data for acetonitrile-hydrogen halide systems and declared that the hydrogen halides are weak electrolytes in acetonitrile, being only slightly ionized. Their data appear to place the acid function in the order HI HBr HCl, but the spacing is very different for the various sites of basic function. Assuming Ao to be 176 for HBr, the degrees of dissociation of 0.0001,0.001, and 0.01 M HBr solutions in acetonitrile were computed to be 0.13, 0.09, and 0.07, respectively. 

It was mentioned that Pleskov reported A for HCl as 178 for 0.001 m HCl, 200 times as large as Janz and Danyluk s value, a difference which could not be accounted for. 

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Nitrile oxides (R-C=N -0"), ° which can be generated by base-catalysed elimination of hydrogen halide from halo-oximes (RC(Hal)=NOH), or by dehydration of nitro componnds (RCH2NO2), readily add to alkenes and to alkynes, generating tive-membered heterocycles. Addition to an alkene produces an isoxazoline, unless the alkene also incorporates a group capable of being eliminated in a step after the cycloaddition, as shown below. However, isoxazolines can also be dehydrogenated to the aromatic system. ... 

CARBON SKELETON. The technique of precolumn catalytic hydrogenation can be applied to reduce certain unsaturated compounds to their parent hydrocarbons. Compounds analyzed by this technique include esters, ketones, aldehydes, amines, epoxides, nitriles, halides, sulfides, and fatty acids. Fatty acids usually give a hydrocarbon that, is the next lower homolag than the parent acid. For most systems utilizing hydrogenation, hydrogen is also used as the carrier gas. Usually 1% palladium or platinum on a non-adsorptive porous support such as AW-Chromosorb P is used as the catalytic packing material. 

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