P-chlorobenzonitrile

Cations, cyclopropeny1, 54, 97 o-Chlorobenzaldehyde, by reduction of o-chlorobenzonitrile with Raney nickel alloy in formic acid, 51, 23 p-Chlorobenzaldehyde, by redaction of p-chlorobenzonitrile with Raney nickel alloy, 51, 22... 

Addition of a suspected intermediate. If a certain intermediate is suspected, and if it can be obtained by other means, then under the same reaction conditions it should give the same products. This kind of experiment can provide conclusive negative evidence if the correct products are not obtained, the suspected compound is not an intermediate. However, if the correct products are obtained, this is not conclusive since they may arise by coincidence. The von Richter reaction (3-25) provides us with a good example here too. For many years it had been assumed that an aryl cyanide was an intermediate, since cyanides are easily hydrolyzed to carboxylic acids (6-5). In fact, in 1954, p-chlorobenzonitrile was shown to give p-chlorobenzoic acid under normal von Richter conditions.29 However, when the experiment was repeated with 1-cyanonaphthalene, no 1-naphthoic acid was obtained, although... 

The following couples were tested p-chlorobenzonitrile/p-chloro-acetophenone, p-chloroacetophenone/p-chlorodiphenyl, p-chlorodiphenyl /chlorobenzene, p-chlorodiphenyl/p-chlorofluorobenzene, chlorobenzene /p-chlorotoluene, chlorobenzene/p-chloroanisole, p-chloroacetophenone/ methyl ester of m-chlorobenzoic acid, chlorobenzene/m-chlorotoluene, p-chlorodiphenylether/p-chlorotoluene, m-chlorodiphenylether/chloroben-zene, m-chlorodiphenylether/p-chlorotoluene, chlorobenzene/methyl ester of m-chlorobenzoic acid, chlorobenzene/p-bromoanisole, p-bromoaceto-phenone / p-chlorobenzonitrile, p-bromobenzonitrile / p-chloroacetophe-none, bromobenzene/p-chlorodiphenyl, m-bromotoluene/chlorobenzene, and p-chlorodiphenyl/p-bromotoluene. 

Figure 21.1 Cyclic voltammograms in DMF-0.1 M Et4NC104 at a scan rate of 80.6 mV/s on a planar platinum electrode (top) 2.15 x l O 3 M p-chlorobenzonitrile (bottom) 1.44 x 10 3 M benzonitriie. Numbers 1 and 2 represent cycles 1 and 2, respectively. [From Ref. 1, reprinted with permission.]...

D. The chronoamperometric results can also be used to ascertain the number of electrons involved in the formation of benzonitrile from p-chloro-benzonitrile. In order to translate the chronoamperometric data into a meaningful n value, a compound is selected that has a diffusion coefficient very similar to that of p-chlorobenzonitrile and that gives a stable, known product upon electroreduction. Tolunitrile, which satisfies these criteria, is known to be reduced to its radical anion at a diffusion-controlled rate. Since this one-electron process gives a value of 168 pA s1/2- M x cm 2 for it1/2/CA, the corresponding value of 480 pA s1/2 A/ 1 cm-2 for the reduction of p-chlorobenzonitrile to benzonitrile anion radical must represent an overall three-electron process. When we subtract the one electron that is required to reduce benzonitrile to its radical anion from this total, we immediately conclude that two electrons are involved in cleavage of the carbon-chlorine bond in p-chlorobenzonitrile. A scheme that is consistent with these data is described by Equations 21.1 to 21.6. 

Similar enamines were obtained from a- and (3-naphtonitriles,180 and the same ASMA has been prepared from p-chlorobenzonitrile.181... 

The reactions of monoanions of /Fdicarbonyl and / -cyanocarbonyl compounds with aryl halides have been induced electrochemically187. Thus 4-bromobenzophenone and p-chlorobenzonitrile give, with 138 in DMSO, good yields of substitution products. 

Pyrrole anion is unreactive in liquid ammonia under irradiation with PhBr or 1-chloro-naphthalene. However, the reactions of aryl chlorides (p-chlorobenzonitrile, 3- and 4-chloropyridines and 4-chlorodiphenyl sulphone) with 2,5-dimethylpyrrole anion under electrochemical inducement in the presence of a redox mediator gave the C3-substituted product in moderate yields (35-40%) (equation 120)225. The rate constant of the coupling reaction between this nucleophile and aryl radicals is about 5-8 x 109 M"1 s 1 determined by electrochemical methods225. 

With PhTe" ions the symmetrical telluride (/ -NCC6H4)2Te was formed. With p-chlorobenzonitrile, whose radical anion has a slow rate of fragmentation, the yield of 254 was 70%309a. However, with o- and m-chlorobenzonitriles the yields of the products were low, but in the presence of l,2-di(4-pyridyl)ethylene as redox catalyst, the yields could be improved310. 

No thiolate substitution of p-dichlorobenzene, 1,2,4,5-tetrachloro-benzene, or pentachlorophenylanisole in alcohol was observed Substitution of 2,3,4- and 2,4,5-trichlorobenzonitrile, 2,3-, 2,5- and 3-4-dichlorobenzonitrile and o- and p-chlorobenzonitriles with sodium hydrogen sulphide in liquid ammonia afforded the cyanothiophenols. Preferential replacement of the p-Cl was observed. Meto-chlorobenzo-nitrile did not undergo nucleophilic substitution under these conditions, but was rather hydrolysed by the water present in the NaSH . ... 

Figure 6.18 shows a voltammogram for p-chlorobenzonitrile [16]. The main features are an irreversible peak at —1.96 V and a reversible process at more negative potentials, = —2.32 V. The first peak remains irreversible at all sweep rates investigated even if the scan is reversed at —2.20 V (i.e. before... 

A soln. of p-chlorobenzonitrile and a moderate excess of Na-hypophosphite in a pyridine-acetic acid-water mixture acid to litmus treated with Raney-Ni and stirred 2 hrs. at 40-45° p-chlorobenzaldehyde. Y 80%.—This procedure requires neither special apparatus nor particular precautions. F. e. and limitations s. O. G. Backeberg and B. Staskun, Soc. 1962, 3961. 

A suspension of triphenylbenzylphosphonium chloride in benzene converted to the ylid by refluxing with n-butyl- (or methyl-) lithium for 1 hr., powdered anhydrous Lil added, refluxing continued 1 hr., a soln. of p-chlorobenzonitrile in benzene added gradually, refluxed 2 days, the solvent removed, treated successively with methanol, water, and HGl, then refluxed 2 hrs. 4 -chloro-desoxybenzoin. Y 81%. - The nitrile is activated by Li-ion as a Lewis acid. This method seems to be superior to the usual Grignard method in the case of alkyl cyanides with a-hydrogen atoms. F. e. s. R. G. Earnhardt, Jr., and W. E. McEwen, Am. Soc. 89, 7009 (1967). 

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