Tetracyanoethylene oxide

Caution Both tetracyanoethylene and tetracyanoethylene oxide slowly evolve hydrogen cyanide when exposed to water. Therefore all operations should he conducted in an efficient hood and contact with the skin should he avoided. 

Tetracyanoethylene may be purchased from the Columbia Organic Chemicals Co., the Eastman Kodak Co., or prepared by the method of Carboni. This procedure has been simplified in this laboratory as follows.  

Eastman Kodak Co. practical grade is sufficiently pure for the reaction. 

The rate of addition of hydrogen peroxide is fairly fast initially but is slowed to maintain the indicated temperature. It is important to get the reaction over in a short time (5-7 minutes) for the best yield. 

It is wise to use a mechanical or magnetic stirrer in order to induce rapid crystallization of the product. Prolonged contact of the product with water at this stage diminishes the yield markedly. The presence of anions, e.g., chloride, can lead to more rapid decomposition of the product, and it is best to use distilled water and ice prepared from distilled water at this point. If the oil cannot be induced to crystallize rapidly, more ice water should be added. 

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Tetracyanoethylene oxide [3189-43-3] (8), oxiranetetracarbonitnle, is the most notable member of the class of oxacyanocarbons (57). It is made by treating TCNE with hydrogen peroxide in acetonitrile. In reactions unprecedented for olefin oxides, it adds to olefins to form 2,2,5,5-tetracyanotetrahydrofuran [3041-31-4] in the case of ethylene, acetylenes, and aromatic hydrocarbons via cleavage of the ring C—C bond. The benzene adduct (9) is 3t ,7t -dihydro-l,l,3,3-phthalantetracarbonitrile [3041-36-9], C22HgN O. 

The stable dicyanomethylides 274, made directly from the triazolopyridines and tetracyanoethylene oxide (TCNEO) reacts more slowly with MEP in acetonitrile to give mainly indolizines, with cyclazines as secondary products formed... 

The ylide 44, prepared from the corresponding diazine and tetracyanoethylene oxide, rearranges in methanol the give the 1,3-diazepine 45 <96TL1587>. The x-ray geometry for 45 is reported. 

Tetracyanoethylene oxide (100) added to allene through cleavage of the epoxide ring to give 3-methylene-2,2,5,5-tetracyanotetrahydrofuran (101) in good yield [90]. 

Tetracyanoethylene oxide, with n-butyl sulfide to give carbonyl cyanide,... 

The distillate is treated with tetracyanoethylene oxide to remove the small amount of w-butyl sulfide that codistills with carbonyl cyanide. 

The yield is based on the amount of tetracyanoethylene oxide initially charged. 

Triazines react with tetracyanoethylene oxide to afford the stable triazinium 2-dicyanomethy-lides (72). 

The only other dipolar species that has been added to thiophene is the carbonyl ylide (287). Thus tetracyanoethylene oxide, as the carbonyl ylide, reacts with thiophene to form the adduct (288) in 70% yield (65JA3657, 68T2551). Several monosubstituted thiophenes have been used in this reaction. From competitive experiments it has been shown that the rate of cycloaddition to furan and benzo[6]furan is greater than that to thiophene and benzo[6]thiophene respectively (75ACS(B)441). 

Linn and Benson discovered in 1963 the ability of tetracyanoethylene oxide (145) to react with alkenes and alkynes at elevated temperatures in [3 + 2] cycloadditions.139 The kinetics of the reaction of (145) with styrene revealed that the formation of (147) is preceded by a first-order step consisting of the electrocyclic ring opening to the carbonyl ylide (146 Scheme 33). 

The decomposition of (18) in the presence of electron-deficient oxygen acceptors such as tetracyanoethylene forms the tetracyanoethylene oxide (19)51, with 60% yield. The oxygen atom transfer may be considered a general reaction of carbonyl oxides in ozonolysis of C=C double bonds when oxygen-accepting substrates are present. 

Tetracyanoethylene oxide (TCNEO) not only oxidizes sulfides to sulfoxides but also reduces sulfoxides to sulfides with generation of two molecules of carbonyl cyanide (17). The reduction mechanism involves a zwitterion intermediate (15) that produces sulfide and two molecules of (17) by simultaneous cleavage of the C—C and O—S bonds. A mechanism (Scheme 14) that involves a zwitterion (16) as a common intermediate is proposed for the formation of ylide and sulfoxide.311... 

A series of symmetrical and unsymmetrical active methylene compounds was reacted with salt 20 to give 5-alkylydene-l,2,3-dithiazoles 83 <1999T9651>. More surprisingly, tetracyanoethylene oxide gives under these conditions dicyanomethylene derivative 42 (Scheme 8) <1998J(P1)2505>. 

Naphthyridine with tetracyanoethylene oxide gave l,6-naphthyridin-6-ium-6-dicyanomethanide (12) (substrate, THF, <5°C synthon/THFJ, dropwise, <5°C, 24 h 63%) 857 also analogous reactions.101,857... 

Pyrazine gave 1,4-pyrazinediium bis(dicyanomethylide) (9) (tetracyanoethylene oxide, PhMe, reflux, 6 h 45% X-ray confirmation of structure).62, cf 573... 

A solution of 5,10,15,20-tetraphenylporphyrin (0.08 mmol) and tetracyanoethylene oxide (0.34 mmol) dissolved in 2 ml 1,2-dibromoethane were refluxed 1 hour. The solvent was evaporated in vacuo and the product isolated by chromatography on silica using hexane/chloroform, 1 1. H-NMR, UV-Vis, MS, and elemental analysis data supplied. 

When 5,15-diphenylporphyrin was refluxed 3 hours in toluene with tetracyanoethylene oxide, two compounds were formed by a /3-addition as illustrated in Eq. 1. In a subsequent investigation by the author (4), however, it was discovered that if the mixture was refluxed 24 hours, only the tetracyano derivative would be obtained. 

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