Cyanide, tetraethylammonium

Dichloroanthaquinones have also been converted into the corresponding dicyano derivative, via what has been claimed to be the disulphonic acid (vide supra) [76]. Chloropurines have been converted into the corresponding cyano compounds using tetraethylammonium cyanide [77]. 

Reactions between aromatic hydrocarbon radicabcations and cyanide ions, with few exceptions, give low yields of nuclear substitution products [76], In some cases, better results have been obtained by anodic oxidation of the aromatic compound in an emulsion of aqueous sodium cyanide and dichloromethane with tetra-butylammonium hydrogen sulphate as a phase transfer agent [77, 78]. Methoxy-benzenes give exceptionally good yields from reactions in acetonitrile containing tetraethylammonium cyanide, sometimes with displacement of methoxide [79, 80]... 

Caution. Tetraethylammonium cyanide is a hygroscopic solid that is readily absorbed through skin and is toxic by this route, via inhalation of the dust or if swallowed. Use suitable protective clothing and handle in a well-ventilated hood. 

The solubility of the components in the solvent must be sufficient. To improve the solubility, cosolvents can be used. Another possibility is the application of a two-phase system or an emulsion in the presence of phase-transfer catalysts. A two-phase system also has advantages in product isolation and continuous electrolysis procedures. A typical example is the synthesis of p-methoxy benzonitrile by anodic substitution of one methoxy group in 1,4-dimethoxybenzene by the cyanide ion (Eq. 22.21). The homogeneous cyanation system (acetonitrile, tetraethylammonium cyanide) [24] can be efficiently replaced by a phase-transfer system (dichloro-methane, water, sodium cyanide, tetrabutylammonium hydrogen sulfate) [71]. 

A column, identical to that described in part 1 of Sec. A, is packed with 1 lb of IRA-400 resin and charged with 454 g (9.26 moles) of sodium cyanide dissolved in 4 1. of 50% aqueous methanol. The column is then rinsed with 5 1. of anhydrous methanol. A solution of 44 g (0.21 mole) of tetraethylammonium bromide in 400 ml of anhydrous methanol is prepared and placed on the charged anhydrous column. The collection and purification of the tetraethylammonium cyanide are carried out exactly as described for the cyanate, except that purification of the cyanide is always necessary. After the product is isolated from the acetonitrile-ethyl acetate solution, it is dried under dynamic vacuum at ambient temperature for 24 hr. The yield, based on tetraethylammonium bromide, is 20 g (60%). Anal. Calcd. for C9H20N2 C, 69.23 H, 12.82 N, 17.95. Found C, 69.1 H, 12.7 N, 17.7. 

Since direct substitution of 4-chloroquinazolines with cyanide without a suitable catalyst has no preparative value (cf. p 131), displacement of the 4- or 2-trimethylammonium group in 1 with cyanide using potassium cyanide or tetraethylammonium cyanide is the most convenient method for the preparation of quinazoline-4-carbonitriles 2B and quinazoline-2-carbonitriles 2A, respectively. Trimethylquinazolinylammonium chlorides are easily obtained from respective chloroquinazolines and trimethylamine. ... 

Direct synthesis of quinoxalinecarbonitriles 10 is possible by reaction of chloroquinoxalines 9 with tetraethylammonium cyanide under mild reaction conditions. ... 

Chloropurines are less reactive and the displacement with cyanide under these conditions was unsuccessful. However, the use of tetraethylammonium cyanide with trimethylamine as catalyst allows this conversion to be carried out very readily at room temperature an example is the formation of 7. ... 

The tellurocyanate ion is stabilized by bulky onium cations. The reactions of tellurium with tetraethylammonium cyanide in dimethylformamide or acetonitrile , with tetramethyl-ammonium cyanide in acetonitrile , with tetraphenylarsonium cyanide in acetonitrile , or with bis[triphenylphosphane]iminium cyanide in acetone produced onium tellurocyanates that were isolated by evaporation of the solvent. The dry salts are reported to be unaffected by oxygen . Moist air and wet solvents decompose the tellurocyanates with depostion of tellurium . 

Thallium(I) cyanide was introduced by Taylor and McKillop as a reagent. Aromatic and heteroaromatic acyl cyanides are produced in go yield, whereas aliphatic acid halides lead under these conditions mainly to dimerization products. 18-Crown-6 is a good catalyst for the preparation of cyanoformate in methylene chloride with potassium cyanide and chloroformates. Similarly, tetraethylammonium cyanide gives cyanoformates in high yield under very mild conditions. Aroyl cyanides are generated easily by phase transfer catalysis with tetra-n-butylammonium bromide. Tri- -butyltin cyanide proved successful only with aromatic acid halides, leading to dimerization products with aliphatic compounds. ... 

In a two-phase system (water/cyclohexane) amidinium salts react with alkali metal cyanides to form bis(dialkylamino)carbonitriles (519 equation 231). With the aid of tetraethylammonium cyanide the aziridinium salt (520 equation 232) was transformed to the nitrile (521). ... 

Finch et al. [93FIN/GAR] determined the enthalpy of formation of the cyanide ion from the enthalpies of combustion of tetramethyl- and tetraethylammonium cyanide. The molar enthalpies of formation so obtained were combined with experimental determinations of the enthalpies of dissolution of the salts and the enthalpies of formation of (CH3)4N and (C2H5)4N as auxiliary data. The consistent results so obtained yielded Af//° (CM", 298.15 K) = (140.3 +2.2) kJ-mol" as the mean. As this result is significantly smaller than the result obtained from the hydrogen cyanide route it was not included in the selection. 

Tetraethylammonium cyanide, (C2Hs)4N CN light, hygroscopic. Supplier Fluka. 

NITRILES 18-Crown-6. Dichloromethylenedimethylammonium chloride. 0-2,4-Dinitro-phenylhydroxylamine. N-Ethylacetonitrilium tetrafluoroborate. Hydroxylamine-O-sul-fonic acid. Methyltricarylylammonium chloride. Phenyl chlorsulfite. Phosphonitrilic chloride. Tetraethylammonium cyanide. Tosylmethyl isocyanide. Triethyl orthoformate. Triphenylmethylisocyanide. 

Tetrachlorobenzyne, 523, 524 Tetrachloroethylene, 413 Tetracyanoethylene, 271, 567-568 Tetracyclines, 109 Tetracyclone, 489, 490, 548, 577 9,11-Tetradecadien-l-yl acetate, 546 E-7-Tetradecene-l-ol acetate, 12 1,2,4,5-Tetraenes, 146 Tetraethylammonium bromide, 568-569 Tctraethylammonium chloride, 480 Tetraethylammonium cyanide, 569... 

Tetraethylammonium cyanide, (C2Hs)4N CN . Mol. wt. 156.26. Sensitive to light, hygroscopic. Supplier Fluka. 

An alternative procedure involves the electrolysis of acetonitrile solutions of tetraethylammonium cyanide containing aromatic substrates. Two types of... 

The chlorine in 2-chloropyrimidines and 2-chloroquinazolines is also replaced by cyano, following conversion to the trimethylammonio-derivatives and subsequent reaction with tetraethylammonium cyanide. ... 

Stoichiometric amounts of tetraethylammonium cyanide react with aliphatic bromides in dichloromethane, acetonitrile or DMSO to give reasonable yields of the corresponding nitriles [13]. These reactions are clearly related to, but not actually examples of, phase transfer catalysis. It is interesting, however, that under these homogeneous conditions, tetraethylammonium cyanide reacts in acetonitrile with neopentyl bromide to give the corresponding nitrile (see Eq. 7.3). Bimolecular displacements on such sterically hindered substrates are usually quite difficult to effect. 

Typical cyano quench Iodine monochloride (l.OM in DCM, 1.3 equiv) is added dropwise to a solution of the MOM or BOM protected homoallylic alcohol (1 equiv) in toluene (0.01 M) at —78°C. In a separate flask, tetraethylammonium cyanide (1.5 equiv) is dissolved in acetonitrile (0.8 M) containing 4-A molecular sieves (MS) (Ig/mmol). Toluene (0.4M) is added and the Et4NCN solution transferred to the reaction mixture... 

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