Trimethylene Cyanide

Several procedures for making glutaric acid have been described in Organic Syntheses starting with trimethylene cyanide (28), methylene bis (malonic acid) (29), y-butyrolactone (30), and dihydropyran (31). Oxidation of cyclopentane with air at 140° and 2.7 MPa (400 psi) gives cyclopentanone and cyclopentanol, which when oxidized further with nitric acid at 65—75° gives mixtures of glutaric acid and succinic acid (32). 

The lower boiling fraction is mainly unchanged trimethylene chlorobromide and amounts to 15-20 g. It may be refractionated or used directly in a subsequent run. The high boiling residue is mainly trimethylene cyanide. If the residues from several runs are combined and redistilled an average of 6-7 g. per run of product boiling at 160-165°/26 mm. is obtained. 

Larger runs have been made and the yields are proportional thus a five-mole run gives 210-245 g. of chlorobutyroni-trile and 30-35 g. of trimethylene cyanide. 

The preparation of glutaric acid by the hydrolysis of trimethylene cyanide has been described in a previous article in this series,2 which includes a bibliography of the literature. The present method is a modification of that of Knoevenagel.3... 

Many methods have been mentioned in the literature for the preparation of glutaric acid. Of these, the only methods of preparative interest are the hydrolysis of trimethylene cyanide with acids or alkalies,1 the hydrolysis of methylene dimalonic ester2 or methylene dicyanoacetic ester,3 and the oxidation of cyclopentanone with nitric acid.4 In this country the cheapness of trimethylene glycol makes it the best source for glutaric acid. The method described in the procedure is a modification of that originally described by Reboul.5... 

In a 5-I. round-bottom flask fitted with a stopper holding a reflux condenser and a separatory funnel, are placed 294 g. (6 moles) of sodium cyanide and 300 cc. of water. The flask is heated on a steam bath until most of the sodium cyanide is in solution. This requires two to three hours. A solution of 500 g. (2.47 moles) of trimethylene bromide (Note 1) in 11. of 95 per cent alcohol is then added through the separatory funnel over a period of forty to sixty minutes. The mixture is refluxed for thirty to forty hours (Note 2) on a steam bath. Then the solvent is removed, preferably under reduced pressure. The residue, consisting of sodium bromide, sodium cyanide, and trimethylene cyanide, is extracted with 300-400 cc. of ethyl acetate, which dissolves the trimethylene cyanide and does not dissolve the inorganic salts. This solution is filtered and the salt washed once with about 100 cc. of ethyl acetate. The ethyl acetate is distilled at ordinary pressure (Note 3) and the residual liquid is distilled under reduced pressure. The yield of trimethylene cyanide boiling at i44-i47°/i3 mm. or i3i-i34°/io mm. is 180-200 g. (77-86 per cent of the theoretical amount). 

The only practical method of preparation for trimethylene cyanide is the action of potassium cyanide on trimethylene bromide.1... 

Polymethylene dicyanides are readily prepared from the corresponding dibromides, as illustrated by the preparation of trimethylene cyanide, CN(CH,),CN (86%). The o- and p-o),ct) -dibromoxylenes react rapidly to give only the corresponding phenylenediacetonitriles (70-90%) with the meta isomer, the reaction may be controlled to yield the bromonitrile (90%). - ... 

Cyanides bearing a second group in a suitable position may undergo ring closure on hydrogenation, as illustrated by the formation of piperidine from trimethylene cyanide and pyrrolidines from /3-cyapo esters (cf. method 574). 

Glutiurlc Add. Pentanedioic acid 1,3-propane-dicarboxylic acid. C5H 04 mol wt 132.11. C 45.45%, H 6.10%, O 48.44%. COOH(CHj)3COOH. Occurs in green sugar beets is found in water extracts of crude wool. Manuf from cydopentanone by oxidative ring fission with hot 50% nitric acid in the presence of vanadium pentoxide. Lab prepn by acid hydrolysis of trimethylene cyanide Marvel. 

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