Carbonimidoyl dichloride

An interesting and novel method for the preparation of isocyanides (85) has been reported and represents a new method for the preparation of these compounds in excellent yields. Thus with a variety of alkyl and aryl carbonimidoyl dichlorides (84) cathodic reduction in the range -1.25 V to -1.90 V (see) provides a new, mild and reagent-free method for the preparation of isocyanides in 82-96% yields, as determined by gas chromatography (equation 49)71. 

Also, heating of carbonimidoyl dichlorides with primary amine hydrochlorides in an inert solvent at 180 °C under nitrogen affords carbodiimides. For example, arylcarbon-imidoyl dichlorides 122 react with propylamine to give N-aryl-N -propylcarbodiimides... 

Instead of the second equivalent of the primary amine, triethylamine can also be used. For example, reaction of the sugar carbonimidoyl dichloride 124 with cyclohexylamine and triethylamine gives a quantitative yield of the carbodiimide 125. ... 

The addncts derived from carbodiimides and nncleophiles also undergo thermal elimination reactions to regenerate the carbodiimide, and they are therefore of limited preparative value. For example, the elimination of hydrogen chloride from carbonimidoyl dichlorides is used in the synthesis of arenesulfonylcarbodiimides (see Section 9.2.2). Of course, isoureas and isothioureas also undergo elimination reactions. When the elimination of isothioureas is conducted in the presence of heavy metal ions, the insoluble metal mercaptides are precipitated to facilitate the in situ generation of the carbodiimides. 

The reaction of the ester carbonimidoyl dichloride 27 with primary amines affords the... 

Also, N-4-chlorophenylcarbonyl-N -t-butylcarbodiimide is obtained in a similar manner. The reaction of the bis-carbonimidoyl dichloride 29 with t-butyl amine affords the carbonyl dicarbodiimide 30. ... 

Chloroformamldines are intermediates in the above transformation of carbonimidoyl dichlorides with amines. Often, bases, such as triethylamine are used to affect their dehydrochlorination to give carbodiimides. For example, the substituted chloroformamidines 32 react with triethylamine to give the relatively stable imidoylcarbodiimlde 33 (R = Et,... 

The reaction of phosphorous substituted carbonimidoyl dichlorides 10 with arylamines in the presence of triethylamine affords the corresponding carbodiimides 11. The reaction proceeds via the intermediate chloroformamidines. The dehydrochlorination of the intermediate chloroformamidine occurs in diethyl ether at room temperature. 

In 1874 Sell and Zierold obtained phenylcarbonimidoyl dichloride I in the reaction of phenylisothiocyanate II with chlorine. Several years later, Nef ( 8,109 prepared carbonimidoyl dichlorides by addition of chlorine to isocyanides, such as phenyl isocyanide III. This relationship between I and isocyanides (isonitriles) led to the frequently used term isocyanide dichlorides for the compounds under discussion. 

In addition to the two classical methods of synthesis of carbonimidoyl dichlorides, several new methods were developed more recently. Thus, chlorination of imidoyl chlorides, generated from monosubstituted formamides and thionyl chloride, provides a useful new method to produce a great variety of carbonimidoyl dichlorides Likewise,... 

The carbonimidoyl dichloride structure VI was established recently for tetrameric cyanogen chloride (69.72,131,133 compound which can also be synthesized by chlorinating 2-dimethylamino-4,6-dichloro-l,3,5-triazine VII ( ). 

The synthesis of carbonimidoyl dihalides is not limited to compounds having the N=CX2 group attached to aliphatic and aromatic hydrocarbyl and heterocyclic moieties. Acyl ( 11 125 aroyl (4.55,56,114,125 fonyl (5.7,32,37,1 1 1,1 15 phosphoryl carbonimidoyl dichloridesC " ) have been synthesized, and a variety of other combinations can certainly be visualized. A recent survey of syntheses of carbonimidoyl dichlorides has been published by Kiihle and his co-workers... 

The addition of halogen to isocyanides to produce carbonimidoyl dichlorides was demonstrated by Nef (io8.io9j Guillemard ( ). 

The reaction proceeds in chloroform at room temperature however, no yields are reported. In the aliphatic series it is sometimes advantageous to conduct the reaction in diethyl ether, using sulfuryl chloride as the chlorinating agent. Thus, ethylcarbonimidoyl dichloride VIII is obtained in the reaction of ethyl isocyanide with sulfuryl chloride However, addition of chlorine to long-chain aliphatic isocyanides does not produce the corresponding carbonimidoyl dichlorides ( ). 

N 3-Dimethylaminopropyl)carbonimidoyl dichloride To a solution of 1.44 g of 3-dimethylaminopropyl isocyanide in 11ml of chloroform chlorine is added with ice-cooling until a yellow color is observed. The precipitated 1.45 g (62%) of N-(3-dimethylaminopropyl)carbonimidoyl dichloride, m.p. 130.5-132°C, is collected and dried in vacuo. The compound is very hygroscopic. 

The chlorination of isothiocyanates is the classical synthesis of carbonimidoyl dichlorides. Sell and Zierold in 1874 obtained phenyl-carbonimidoyl dichloride (IX) upon chlorination of phenyl isothiocyanate in chloroform at 0°C, and Nef ( ° ) observed that under the conditions... 

In addition to isothiocyanates, compounds having the configuration RN=C(SX)2 (X = alkyl or K) react rapidly with chlorine to produce carbonimidoyl dichlorides. Thus, Neidlein and his co-workers and Gompper and Kunz ( )obtained arylsulfonylcarbonimidoyl dichlorides X in the reaction of S,S-dialkyl-N-sulfonyldithiocarbonimides XI with chlorine. 

Similarly, carbonimidoyl dichlorides X are obtained upon chlorination of dithiocarbamate salts XIII (5.32,93,98 benzoyldithiocarbamates ( ). 

The chlorination of isothiocyanates and dithiocarbamates is a general method and good yields of carbonimidoyl dichlorides are obtained. However, on attempted conversion of o-nitrophenyl isothiocyanate a reaction mixture was obtained, which decomposed violently upon heating... 

Isothiocyanato groups attached to phosphorus are also readily converted to the corresponding carbonimidoyl dichlorides. For example, chlorination of the phosphorus isothiocyanates XVII yields the carbonimidoyl chlorides XVIII (2.3,i9,64j... 

The mechanism of the chlorination of isothiocyanates involves initial addition of one mole of chlorine to the C=S bond to produce the l-(chloro-thio)formimidoyl chlorides XIX (26.56a,95imidoyl chlorides and demonstrated that addition of a second mole of chlorine converts the intermediate XIX to the carbonimidoyl dichloride. 

The reaction of isocyanates with phosphorus pentachloride, and the reaction of secondary carbamoyl chlorides with chlorine, yield carbonimidoyl dichlorides. Gumpert in 1885 investigated the reaction of phenyl... 

A recent patent describes the formation of carbonimidoyl dichlorides in the reaction of several aliphatic and aromatic isocyanates with phosphorus pentachloride. This reaction can be conducted using phosphorus oxychloride as solvent, or without a solvent however, only from aliphatic isocyanates diisocyanates are good yields of... 

While alkyl and aryl isocyanates are only converted to carbonimidoyl dichlorides by phosphorus pentachloride, arylsulfonyl isocyanates can be directly chlorinated to produce arylsulfonylcarbonimidoyl dichlorides. For example, chlorination of benzenesulfonyl isocyanate at 60 C yields benzene-sulfonylcarbonimidoyl dichloride (XXIX) in unspecified yield ( ). 

In addition to isocyanates secondary carbamoyl chlorides are readily converted to carbonimidoyl dichlorides by high-temperature chlorination, provided one of the alkyl substituents is a methyl group (31.49-52,54 ... 

N,N-dialkylimidoyl derivatives are also converted by high-temperature chlorination into carbonimidoyl dichlorides C ). For example, 4-dimethyl-amino-2,6-dichloro-l,3,5-triazine (XXXVII) reacts with chlorine via two pathways to yield the traizinylcarbonimidoyl dichloride XXXVIII and chloroform, or cyanuric chloride (XXXIX) and trichloromethylcarbon-imidoyl dichloride (" ). 

Chlorophenylcarbonimidoyl dichloride ( ). To a solution of 67.5 g (0.5 mole) of sulfuryl chloride in 150 ml of thionyl chloride, 77.5 g (0.5 mole) of N-(4-chlorophenyl)formamide is added portionwise at 15-20°C. After stirring for several hours at room temperature the reaction mixture is heated slowly to 80°C, and the thionyl chloride is removed by distillation. Vacuum distillation of the residue yields 89 g (86%) of 4-chlorophenyl-carbonimidoyl dichloride, b.p. 110-113V10 mm. 

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