The analogy between dialkylmonoamine-carbon disulfide and the homologous N ,N'-dialkyldiamine-carbon disulfide reactions was discussed in Part I. We will show that a parallelism also is found between the dialkylmonoamine-formaldehyde-carbon disulfide and the N , N'-dialkyldiamine-formaldehyde-carbon disulfide reactions. These have been summarized in Chart I ; as in Part I, the compounds with related structures have the same number with the "A" series representing the cyclic types.Dialkylamine-aldehyde-carbon disulfide products have been patented (1, 2,3) as accelerators for the vulcanization of rubber, although the patents contain no suggestion of molecular structures of the reaction products.Three methods are available for the synthesis of amine-aldehyde-carbon disulfide accelerators. For example, we have found that the compound obtained from methylene-bis-piperidine (I, R and R' = cyclopentamethylene) and carbon disulfide is identical with the compound prepared by Levi (4) from piperidinium N ,N-cyclopentamethylenedithiocarbamate (111, R and R' = cyclopentamethylene) and formaldehyde. Furthermore, we have prepared the same compound from the dithiocarbamate (111) and piperidinomethanol. This would indicate that the order of addition of formaldehyde and carbon disulfide to the amine does not affect the nature of the final product.The third method, which involves the use of an alkylaminomethanol, also makes possible the synthesis of the same type of compound in which the N and N' alkyl groups are dissimilar. The reaction of piperidinomethanol with morpholinium W , N-oxadiethylenedithiocarbamate and with dicyclohexylammonium N , N-dicyclohexyldithiocarbamate resulted in products having dissimilar N , N'alkyl substituents. These also were found to have activity in accelerating the vulcanization of rubber. The structure of the above compounds, which result from the three methods of preparation just described, has not been clearly elucidated. Levi proposed an electrovalent, salt type of structure for his product, namely, methylenepiperidinium N , N-cyclopentamethylenedithiocarbamate (11-alternate, R and R' = cyclopentamethylene) . However, there is also the possibility that the methylene group can act as a purely covalent link between the dithiocarbamic acid and m i n e radicaIs thereby forming a dithioester, N' ,N'-dialkylaminomethyl N , Ndialkyldithiocarbamate (11). In fact similar compounds have been patented by Presented before the Division of Organic Chemistry a t the 110th meeting of the American Chemical Society, Chicago, Ill., Sept., 1946. 952CARBON DISULFIDE WITH MONO-AND DI-AMINES. 11

The literature is replete with reactions of dialkylmonoamines and carbon disulfide; the products are dialkylammonium salts of dialkyldithiocarbamic acids (I) and may be oxidized to thiuram disulfides (II). These compounds are used widely in the rubber industry as vulcanization accelerators. More recently Smith, Alliger, Carr, and Young (1) of this laboratory have shown that, under certain conditions, the oxidation of dialkyldithiocarbamates in the presence of primary or secondary amines may produce thiocarbamylsulfenamides (III). The decomposition of this type of compound by loss of sulfur results in an N,N'disubstituted thiourea (IV).However, analogous reactions of , '-dialkyldiamines with carbon disulfide have received only scant attention and the purpose of this investigation was to study this field of chemistry.It was found that, in general, the reactions of N, N'-dialkylethylenediamines with carbon disulfide follow the same pattern as similar reactions in the dialkylmonoamine series. However, in the diamine series the products are cyclic by virtue of the ethylene chain which links the nitrogen atoms. The analogies between reactions of mono-and di-amines with carbon disulfide are summarized in Chart I; compounds possessing related structures bear the same number with the "A" series representing the cyclic types.The reaction of ethylenediamine and carbon disulfide was first reported by Hofmann (2) who obtained a product shown to be N-(/3-aminoethyl)dithiocarbamic acid (I-A, R = H). He thermally decomposed this acid and obtained hydrogen sulfide and 2-imidazolidinethione (IV-A, R = H). Subsequently these reactions were extended to N-substituted ethylenediamines by Ristenpart (3), Lob (4), van Alphen (5), Sebrell and Clifford, (6, 7), Zienty and Thielke (8), Zienty (9), Newman (10), and Schinzel and Benoit (11).Using similar reactions we have prepared other 1,3-dialkyl-2-imidazolidinethiones from the thermal decomposition of the corresponding N-alkyl-N-(0-alkylaminoethyl)dithiocarbamic acid inner salts (I-A). Furthermore, it was found that the dithiocarbamic acid inner salts could be oxidized to a new type of compound, the tetrahydro-1,2,5-thiadiazine-6-thiones (III-A), and these new compounds likewise could be thermally decomposed to the same 2-imidazolidinethiones. The new heterocyclic compounds, the tetrahydro-1,2,5-thiadiazines, may be considered to be cyclic thiocarbamylsulfenamides, and their mode of