Carbamide derivatives

A general process for the preparation of pyrimidines from diacetylene and carbamide derivatives RC(X)NH2 (X = NH, O, S R = Ph, OH, NH2) with fixation and subsequent cyclization of primary products has been patented (94GEP4308073). 

The formation of the pyrimidine ring is due to the addition of carbamide derivatives to the 1,3-positions of the diacetylene system, and according to Maretina et al. (81UK1252), the primary adducts 35 can be isolated in certain cases. 

Carbamate herbicides, 13 320 Carbamates, 13 108 amine, 16 359 Carbamic acid nitrile, 3 158 Carbamide derivatives, as cellulose solvents, 11 272 Carbamodiimide, 8 158 Carbamoylated gelatin, 12 444 Carbamoyl-methylphosphoryl family, extractants of, 10 789 Carbamyl chlorides, 12 180 Carbanion coordination, 13 656—657 Carbanions, 21 101... 

Dehydration of /3-hydroxy ketones [1, 235, before references]. Schmidt and Moos-miiller29 reported that the reaction of carbodiimides with primary and secondary alcohols is catalyzed by cupric chloride. Corey et al,30 in a synthesis of prostaglandins, found that the reaction of (8-hydroxy ketones with DCC catalyzed by cupric chloride is a useful method for dehydration to the a S-unsaturated ketone under mild, nonacidic, nonbasic conditions. Presumably the hydroxyl group reacts to form a carbamidate derivative which undergoes cycloelimination. 

Lyophyllin was isolated from Lyophyllum connatum (Tricholoma-taceae) by Fugmann and Steglich (368) along with two other carbamide derivatives AT -hydroxy-N,JV-dimethylurea and an amino acid, connatin. 

Carbamide-derived ligands 62a-e were reported by Kim through a well-designed synthetic route depicted in Scheme 15. The diallqrlated diamines 60a-e were prepared in a two-stage step process, involving Schiff-base formation and reduction. These molecules were converted into the corresponding diols 61a-e using l,l -carbonyldiimidazole (GDI). The phosphoramidites 62a-e were then synthesised by treatment of the... 

Urea. Urea (carbamide) CH4N2O, is the most important building block for amino resins because urea—formaldehyde is the largest selling amino resin, and urea is the raw material for melamine, the amino compound used in the next largest selling type of amino resin. Urea is also used to make a variety of other amino compounds, such as ethyleneurea, and other cyclic derivatives used for amino resins for treating textiles. They are discussed later. 

However, the physicochemical properties of nitrogen chloride give no grounds for the explanation of its stability under melt electrolysis conditions. The possibility of the formation of a chlorine derivative of carbamide according to the scheme ... 

The use of nitrourea is generally applicable to the preparation of urea derivatives and usually affords the required carbamide in excellent yield.3 4... 

An example of an expl resin formed from urea and formaldehyde is entered in Vol 5, D1337-R under Dimethylene Peroxide Carbamide . In Vol 6, F165-R it is mentioned under Formaldehyde and Derivatives . The information on this expl is updated in Vol 9 under Tetramethylene-Diperoxide Dicarbamide ... 

Experimental verification of Eq. (12) was carried out for a number of quite different systems curing both in a solution and bulk such as epoxy, epoxy silicone and silicone oligomers, melamine-formaldehyde and carbamide resins, derivatives of furan resins [11,28,32,63, 81]. Typical results plotted according to Eq. (12) are given in Fig. 18. After phase segregation (t > tp), the experimental dependences fl(t) are completely described by formula (12). The viscosity variation of the dispersion medium is a function of molecular mass andis calculated on the basis of Eq. (12). 

Table II summarizes those amino acids that contain more than an un-reactive aliphatic chain, namely a reactive site which may be a functional group in the traditional sense such as sulfhydryl, thiomethyl, hydroxyl, carboxyl, carbamide, amino, or guanido, or may be an activated aromatic ring or heterocycle such as the phenolic part of tyrosine, the pyrrole unit in troptophan, and the imidazole part in histidine. Phenylalanine would only be considered in this connection as the reactive di- or tetrahydro derivative ring. iV-Peptides derived from proline and hydroxyproline are in a separate class because they are tertiary amides carrying no proton at the nitrogen atom. It may be possible to utilize this special feature for a preferential cleavage under proper conditions.

Rq>lacing the amides by carbamide or its )S-alkyl or aryl derivatives, the general formula of the products becomes... 

By replacing the amides of ehloracetic acid by carbamide or its jS-alkyl or aryl derivatives in the reaction described in the preceding section, the carbamides and substituted carbamides of the arylglycine-arsinic acids may be obtained these have the general formula ... 

The chief interest in this group of acids centres around 3 4-diaraino-phenylarsinie acid. When diazotised tliis acid yields an azoimide, and condensation with gluconic acid, phosgene, and phenanthraquinone, yields, respectively, a digluconyl derivative, a carbamide, and an azine. Condensation with 1 2-diketones such as diacetyl, benzil and its Hi-nitro-, p-methoxy-, 2 -ethoxy-, and jj-dimethylamino-derivatives, also piperil and furil, yields arsenated quinoxalities, e.g. 

This acid is obtained bj reducing the corresponding nitro-acid (p. 171) with ferrous chloride and alkali. It is instantly soluble in an excess of normal hydrochloric acid, and with sodium nitrite gives an orange-brown solution which couples with j8-naphthol. The monohydrochloride of the arsinic acid crystallises in clear prisms calcium, magnesium and barium salts may be obtained. The acetyl derivative separates in small prisms, sparingly soluble in boiling water, readily soluble in acids, sym.-Carbamide of 3-amino-4-piperidinophenylarsinic acid,... 

Ureas. Urea adducts (and those of the closely related A-alkylated derivatives) may be prepared from nonaqueous solvents alternatively, preparation in aqueous alcoholic solution leads to the formation of hydrates. In contrast to the carbamides discussed above, there is relatively little variability in the coordination number of reported urea adducts of tetravalent actinides. Most complexes are either six- or seven-coordinate higher coordination numbers are observed for the larger thorium ion (Table 15). 

However, the compounds formed by the electrolysis of the carbamide-NIHCl melt exhibit a strong depassivating action, which is much stronger than that of Cf (this was proved when studying the electrochemical behavior of titanium in this melt) [10]. Therefore, it appears not very correct to consider that the chlorine derivatives of carbamide can have such properties. If one bears in mind that cyanamide is formed by carbamide electrolysis and taking into account that the formation of the compound is only observed if the melt contains ammonium ions, then the following reaction is possible at the anodic discharge potential ... 

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