Carbamoic acid

In 1906 Leuchs observed, first on glycine, that iV-carboethoxyamino acid chlorides at temperatures as low as 70 °C are transformed, with the loss of alkyl chloride, to the so called Leuchs schen Korper (Leuchs substances), N carbamoic acid amino acid inner anhydrides. As he noted in the case of the glycine derivative these AT-carboxyanhydrides (NCA-s) readily polymerize. For instance in the presence of a small amount of water they form poly-a-amino acids consisting, as shown by later studies, of several hundred residues. 

A further reagent for the relatively selective removal of the Z-group is a concentrated (33%) solution of hydrobromic acid in glacial acetic acid. This mixture, introduced by Ben Ishai and A. Berger in 1952, removes the benzyloxy-carbonyl group at room temperature within an hour through the catalyzed attack of the Br" anion on its benzyl moiety which is converted thereby to benzyl bromide with the liberation of an unstable carbamoic acid (Fig. 9). 

This opened up the attractive possibihty of incorporating the amino group into an ester of carbamoic acid. In the resulting urethane cleavage of the ester and the ensuing decarboxylation regenerate the free amine ... 

Polycondensation of highly reactive intermediates is usually described in a simple fashion. Ring opening by a trace of water yields a carbamoic acid which looses carbon dioxide and regenerates the amino acid ... 

AI3-26152 Bis(dibutyldithiocarbamato)nickel Carbamo-dithioic acid, dibutyl-, nickel(2-i-) salt Dibutyidithio-carbamic acid, nickel salt (Dibutyldithiocarbamato)-nickel(ll) EINECS 237-696-2 HSDB 2950 Naugard NBC NBC Nickel bis(dibutyldithiocarbamate) Nickel(ll) dibutyldithiocarbamate Nocrac NBC NSC 4797 Perkacil NDBC Rylex NBC UV Chek AM 104 Vanguard N. Nickel chelating UV stabilizer (dr polyolefins and accelerator for rubber. Akzo Chemie DuPont UK Uniroyal... 

Substitution of a carbonyl containing functional group generally decreases the antifungal activity in coumarins. For example carbamo-dithioic acid esters of 3-acetylcoumarins (54) do not show activity against Trichophyton sp. and Microsporum sp. [259]. 

The column medium is a polystyrene-divinylbenzene polymer with octylphenyl-N,N-diisobutyl carbamo-ylphosphine oxide extractant adsorbed on the hydrophobic polymer matrix. The carbamoylphosphine oxide functional group is an avid chelator for actinides in 0.16 M or higher concentration nitric acid, whereas alkali and alkaline earth metals are poorly bound. Lanthanides are only retained on the column at much higher nitric acid concentrations (>6 M). Therefore, even these are eliminated from the final matrix under the rinse conditions employed. A very hard base anion ligand is necessary to compete effectively with the carbamoylphosphine oxide ligands and elute actinides, including uranium, in a small volume. In Protocol 1, the fluoride ion from dilute hydrofluoric acid (HF) was chosen for this purpose. 

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