Hydrogen halides nitriles

Synthesis of Heterocycles by Intramolecular Acylation of Nitrile-Hydrogen Halide Adducts ... 

Intramolecular azomethine ylide cycloaddition to the C—O double bond of an aldehyde was reported in 197369 and cycloaddition to the C—C double bond was first reported in 1975.70 Competition between 1,1- and 1,3-cycloaddition is observed in intramolecular reactions, although intermolecular reactions give only 1,3-cycloaddition. Photolysis of 2//-azirines is one generation method of nitrile ylides applicable to intramolecular cycloaddition.70 Another method involves the base-catalyzed 1,3-elimination of hydrogen halide from alkenyl imidoyl halides. Still other procedures involve thermolytic and photolytic cycloreversions of oxazolinones and dihydrooxazaphospholes. 

The cycloaddition of 1-halogeno-l-nitroethene with nitrile /V-oxides leads to the nitro derivatives of isoxazole [520-524], Thus, for example, the reaction of equimolar amounts of 1-chloro- or 1-bromonitroethene with benzonitrile /V-oxidc gave 5-nitro-3-phenylisoxazole [520], The same compound is formed in the reaction of nitrile /V-oxides with ra .s-2-chloro-1 -nitrocthcnc [485], The formation of nitroisoxazoles in these reactions can be explained by the fact that the initial products from the cycloaddition of halogenonitro-A2-isoxazolines more readily eliminate a molecule of hydrogen halide and not HNOr... 

Synthesis of heterocycles, by intramolecular acylation of nitrile-hydrogen halide adducts ... 

Boyd, R. J., Hydrogen bonding between nitriles and hydrogen halides and the topological properties of molecular charge distributions, Chem. Phys. Lett. 129, 62-65 (1986). 

Isocyanato- and 2-isothiocyanatobenzonitriles 1 react with hydrogen halides in dibutyl ether to give 4-haloquinazolin-2(li/)-ones and -quinazoline-2(l//)-thiones 2, respectively. The ring closure is based on a nucleophilic attack of the intermediary nitrile-halide adducts at the carbamic or thiocarbamic acid chloride function. 

The C=0, —COOH, —COOR, and —CN groups are powerful electron-withdrawing groups, and therefore would be expected to deactivate a carbon-carbon double bond toward electrophilic addition. This is found to be true a,j8-unsaturated ketones, acids, esters, and nitriles are in general less reactive than simple alkenes toward reagents like bromine and the hydrogen halides. 

The formation of alkanenitriles from alcohols and HCN is of no interest for laboratory preparations. However, a large number of publications, particularly patents, have appeared, which deal with technical applications of this procedure. A few review articles " serve very well as introductions to this field. Under particularly mild conditions allyl and propargyl alcohols can be transformed into the corresponding nitriles with hydrogen halides in the presence of Cu salts. - The possibility of generating nitriles from alcohols via the analogous halides needs no further treatment at this stage. 

The formation of amide chlorides from nitriles and hydrogen halides under anhydrous conditions is a well-known reaction of wide scope7- There has been some confusion on the nature of the reaction products, but it has turned out that the isolable species are amide chlorides. The thermal stability of the addition products strongly depends on the acidity of the hydrogen halide used. Iodides are more stable than bromides, which in turn are more stable than the chlorides. As a consequence, thermally stable HQ adducts (38 equation 22) can be prepared if Lewis acids ate present, which incorporate the chlorine anion to give a less basic anion (39). 

Thiols and benzenethiols add to nitriles in the presence of hydrogen halides to give iV-unsubstituted iminium salts, e.g. (118, equation 74). The reaction seems to have no advantage over other known preparative procedures. 

Alkylmercaptomethyleneiminium salts (267 Scheme 39), which are accessible either by addition of thiols to the nitrile function in the presence of hydrogen halides or by reaction of chloroformic acid thioethyl ester with thioamides, can also be transformed to the corresponding thioimidates (268). 

Zil berman, E. N. Reactions of nitriles with hydrogen halides and nucleophilic reagents. Russ. Chem. Rev. 1962, 31, 615-633. 

The course of the reaction between halogenoboranes and the aminoben-zonitriles depends upon the position of the NH2 group.169 With the 3- and 4-amino-derivatives the products are the corresponding amine-boranes and compounds obtained by loss of hydrogen halide, (25) and (26). With the 2-amino-benzonitrile, however, the nitrile group is inserted into a B-halogen... 

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. ... 

Examples include high-pressure hydrolysis of a nitrile paraffin autoxidation homogeneous aldehyde hydrogenation olefin hydroformylation to alcohol with paraffin by-product formation, aldehyde condensation to heavy ends, and olefin isomerization cyclo-addition reactions and hydrogen-halide reactions. 

In this respect, both free nitrile molecules and their complex salts with acidic catalysts can take part in the formation of the triazinc.146 Hydrogen chloride, sulfuric acid, Lewis acids and complexes of Lewis acids and hydrogen halides are generally used as catalysts the complexes usually have the best catalytic potential.147-150... 

Addition of hydrogen halide to unsaturated alcohols, ethers, carbonyl compounds, and nitriles... 

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