Benzyl cyanide nitration

In a round-bottomed flask (capacity 0-5 1.) 8 g. of sodium are dissolved in 120 c.c. of absolute alcohol. Into the solution, which is kept cool in water (precipitation of ethoxide is not detrimental) a mixture of 36 g. of benzyl cyanide (p. 137) and 32 g. of ethyl nitrate (p. 148) is poured in small portions. The salt formulated above separates gradually in the shape of almost colourless crystals. In order to allow the reaction to proceed to completion, the flask is left for one hour without cooling, but with exclusion of moisture the precipitate is then collected at the pump and subsequently washed first with alcohol-ether (1 1) and then with ether alone. Yield 40-45 g. 

Finning nitric acid may be used in nitrating benzyl cyanide, but the method here described is cheaper. 

Alkaline nitration with alkoxide bases and nitrate esters was first explored by Endres and Wislicenus who synthesized phenylnitromethane by treating ethyl phenylacetate with potassium ethoxide in ethanol, followed by addition of ethyl nitrate and hydrolysis-decarboxylation of the resulting a-nitroester with aqueous acid. Phenylnitromethane is synthesized in a similar way via alkaline nitration of benzyl cyanide, followed by treatment of the resulting a -nitronitrile with aqueous base. ° Wieland and co-workers used alkali metal alkoxides and nitrate esters for the nitration of cyclic ketones but the yields and purity of product are often poor. ° ... 

In the presence of sodium ethoxide tertiary butyl nitrate reacts with benzyl cyanide to form exclusively butyl ethyl ether and sodium nitrate. In this case no transesterification occurs. Thus the reaction proceeds in accordance with eqn. (56). 

Experimental details for the nitration of benzyl cyanide are also included (Expt 6.21). The product is largely p-nitrobenzyl cyanide (some of the ortho isomer is also formed) the cyanomethyl substituent (as a substituted alkyl group) is thus an ortho/para directing and weakly activating group. 

All samples were analyzed using a gas chromatograph equipped with a flame Ionization detector and a 200 x 0.01" squalane-coated capillary column. Analyses were also made on conventional packed columns In chromatographs equipped with thermal conductivity detectors. Feeds were analyzed on a silver nitrate-benzyl cyanide column. Products were analyzed on a 10 X 1/4" column packed with 25% hexatrlacontane on Chromosorb R. After the Cg s had been eluted, the hexatri-acontane column was backflushed through the detector to determine the heavies content of the sample. 

Light hydrocarbon products were analyzed with a P E F-ll gas chromatograph with a benzyl cyanide-silver nitrate column and flame ionization detector. No effort was made to recover and analyze heavy hydrocarbons. 

A number of a-nitro carboxylic acids are easily dicarboxylated to furnish nitro compounds. The synthesis of nitromethane in this manner is a classical example (38%). Nitroethane and higher homologs have been similarly prepared from the a-bromo acids and sodium nitrite. Another example is found in the synthesis of phenylnitromethane. Treatment of benzyl cyanide with methyl nitrate in the presence of sodium ethoxide gives the sodium salt of the aci-niao compound, which is then hydrolyzed and decarboxylated. ... 

Preparation of phenylnitromethane. A solution of sodium ethoxide prepared from 2 g. atoms of sodium and 400 ml. of absolute ethanol is treated with 100 ml. of absolute ethanol and cooled to 0°, when the sodium ethoxide separates as a hard cake. A second 100 ml. portion of ethanol is added, and a chilled mixture of 2 moles of benzyl cyanide and 2.8 moles of methyl nitrate is added with shaking at 5-15°. The reaction proceeds smoothly, with separation of the nci-nitro sodium salt (1). I he salt is collected (300-320 g.), placed in a 4-1. beaker, and treated with a solution... 

Phenylnitromethane has been prepared by the nitration of toluene with dilute nitric acid in a sealed tube, by the interaction of benzenediazonitun chloride and nitromethane in alkaline solution,2 by the action of silver nitrite on benzyl chloride or iodide, and by the condensation of ethyl rdtrate with benzyl cyanide and subsequent hydrolysis. The use of methyl nitrate, which can be prepared with less danger and difficulty than ethyl nitrate, is advantageous. 

Silver nitrate—benzyl cyanide Specific for cis and trans alkenes 50... 

For example, dropping a mixture of benzyl cyanide and methyl or ethyl nitrate into a cooled alkoxide solution leads to an 80% yield of 2- a-nitro-2-phenylacetonitrile, which gives phenylnitromethane on hydrolysis and decarboxylation.155,156 Ethyl phenylacetate also gives phenylnitromethane analogously and in the same yield.157 Further examples are described by Wislicenus and Wren.158 Wieland et al.159 have converted cyclohexane by this method into the potassium salt of 2-aa-nitrocyclohexanone in about 40% yield, and cyclo-pentanone almost quantitatively into the dipotassium salt of 2,5-di-fla-nitrocyclopentanone. 

If sodium ethoxide is used, only butyl ethyl ether and sodium nitrate are produced in the reaction between tert-butyl nitrate and benzyl cyanide. Transesterili-cation reaction would not happen in this circumstance. 

In Table 13.3.12, k pp approached a constant value when nitrobenzene (1.0 M) was added. This result indicates that solvation of die transition structure for the reaction of benzoyl chloride with sodium nitrate reached an upper limit. Benzyl cyanide is a polar solvent. The value of k pp increased with increased content of benzyl cyanide. Further, highly basic diethylaniline (QH5N(Et)2) could increase the eoneenlration of free PNO and also the reaction rate. However, this compound is less polar flian diehloromethane and the polarity decreased with increased proportion of diefliylaniline, which caused the value of k pp to de-... 

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