Carbamic acid derivatives

These reactions can be opened up to all substances that can yield aniline derivatives in acid or basic medium. Carbamic acid derivatives, numerous variations of which are used as plant treatment agents, provide a striking application. As do urea herbicides and a variety of drug substances e. g. benzodiazepines or phenylbutazone derivatives. 

In the case of 271a and 271b, covalently bound adducts of 271a, b and CO2 (e. g., carbamic acid derivatives) were detected. This was absent in the case of thiol derivative 271c. The concentration of this material could be reduced by heating (a solution to 90 °C for 1 h) and increased by exposing to a CO2 atmosphere. 

Collector TX26 is composed of dialkyl sulphosuccinamate and a mixture of phosphoric acid ester modified with carbamic acid derivative (OMC123) in a ratio of 50 25 25. 

While insect control is more often a limiting factor in tropical bean production, there are several diseases that are serious in certain seasons and locations. Bean rust is one of the most widespread diseases, and it can be controlled effectively with protective fungicides, such as elemental sulfur and certain of the carbamic acid derivatives. The economics of bean production usually preclude any costly applications, however, and the problem has generally been turned over to the plant breeder to solve with resistant varieties. At present, the most practical control of bean anthracnose and the bean blights is through the use of clean seed and resistant varieties. Control with fungicides has always proved difficult and of doubtful value. 

R-NH-COOH), followed by decarboxylation to the aromatic amine, was an important pathway in humans. However, in contrast to loratadine, the carbamic acid metabolite appeared to be sufficiently stable to be detectable in fair amounts in human urine. It can be postulated that the aromatic nature of the amine accounts for the relative stability of its carbamic acid derivative. 

In the reaction of 2-isopropylidene-l-cyclopentanone 201 with carbon disulfide and ammonia, the perhydrocyclopenta[e][l,3]thiazine-2-thione derivative 204 was formed. The probable intermediates of the reaction are the Michael adduct 202 and the 2-imino-l-cyclopentanedithiocarbamic acid derivative 203. Under similar conditions, the related alkylidene derivatives gave the corresponding 3-substituted-2-imino-l-cyclopentanedithio-carbamic acid derivatives. Further substituted derivatives and homologs of 204 were also synthesized (74AKZ319), but the stereochemistry of these compounds was not investigated [73JCS(P1)1009]. 

Reactions of Carbamic Acid Derivatives to Give Semicarbazides 198... 

REACTION OF CARBAMIC ACID DERIVATIVES TO GIVE SEMICARBAZIDES... 

Carbamates, transesteriflcation, 243 IV-Carbamates, 223-234 O-Carbamates, 235-245 Carbamic acid derivatives, reactions to give semicar bazides, 198-199 Carbamoyl chloride, 244 Carbamyl chlorides, 198-200 Carbanilide, see jym-Diphenylurea Carbenes, 52, 62... 

This chapter deals with the kinetics and mechanisms of the hydrolysis of carboxylic acid derivatives of general formula RCOX. These include carboxylic acid halides, amides, and anhydrides with small sections on carboxylic acid cyanides etc. Many recent developments in this field have been made with acid derivatives in which R is not an aliphatic or aromatic group, for example, carbamic acid derivatives, and these are reported where relevant, as are reactions such as ethanolysis, aminolysis, etc. where they throw light on the mechanisms of hydrolysis. 

Volume 10 is devoted to formation and solvolysis of esters and related reactions, with discussion of the effect of neighbouring groups and biological implications, e.g. enzyme action, where appropriate. The first chapter deals mainly with esters of the inorganic acids of phosphorus and sulphur, Chapter 2 with the formation and solvolysis of esters of organic acids and the final chapter with the solvolysis of related derivatives of carboxylic acids, e.g. halides, amides, anhydrides, cyanides, carbamic acid derivatives. 

The most versatile reagent of this group is diethyldithiocarbamic acid (40), which forms coloured and extractable complexes with very many metals, selectivity being assured by control of the pH and the presence of masking agents.52 Here again the practical disadvantages stem from the ease of oxidation and many alternate carbamic acids derived from pyrrolidine and other dialkylamines have been studied. 

Sulfonylureas undergo hydrolysis as shown in the mechanistic scheme in Figure 64 (106). Under acid-catalyzed conditions, water addition leads to loss of an amine and formation of a carbamic acid derivative. Acid-catalyzed loss of CO2 from the carbamic acid derivative yields the corresponding sulfonamide. It was proposed that initial protonation is the rate-determining step in the hydrolysis. 

Reaction with water to the unstable carbamic acid derivative which will undergo spontaneous decarboxylation ... 

Instead of the anticipated formation of the triazolopyrimidine derivative 13 [30-33], the reaction of 8a with ethylchloroformate, through nucleophilic displacement followed by spontaneous hydrolysis of the ester intermediate 11, led to the corresponding carbamic acid derivative 12 (Scheme 4). 

B. Amino and Carbamic Acid Derivatives of 6-Methylergolene and 6-Methyl-... 

A distinctive reaction that uses CO2 is the synthesis of enol carbamate, in which carbamic acid derived from CO2 and amines is added to acetylenes, catalyzed by mthenium complexes. 

Yields are improved in this reaction, relative to phosgene, where the R substituents are small alkyl groups such as methyl or ethyl, although in other cases the reaction was found to be better when phosgene was used. Ring-formed carbamic acid derivatives have been similarly prepared using phenyl chloroformate [806] ... 

Amino groups can be acylated,296,323,348 reaction with sulfonyl chlorides affords the sulfonylamino-substituted products while aryl isocyanates yield carbamic acid derivatives.296, 348,349... 

Carbaryl is a very potent contact and respiratory poison and its spectrum of action is different from that of most of the carbamic acid derivatives. It is very efficient against chewing insects, and proved particularly successful for the control of insect pests in orchards. It is 70 times more toxic than DDT towards bees, but is inefficient against red spider mite (Georghiou and Metcalf, 1962 Haynes et al., 1957 Johnson and Stansbury, 1965). 

Of the carbamic acid derivatives two compounds with similar range of action should be mentioned. 

Carbamic acid derivatives are the group of pesticide compounds with the most varied biological action. They include compounds with insecticidal, fungicidal, and herbicidal action and plant-growth modifiers as well. 

An important application of hydrogenating ester cleavage is involved in Bergmann s benzyloxycarbonyl method of synthesizing peptides.79 In this an amino acid is treated with benzyl chloroformate and then coupled with another amino acid molecule the benzyl group of the resulting benzyl carbamate residue produced is finally removed as toluene, the carbamic acid derivative that results decomposing immediately to carbon dioxide and the desired peptide ... 

The CM anticholine.sterases are thought to inhibit AChE and BuChE in a manner similar to that of OPs. However, instead of an electrophilic pho,sphorus, as in the case of the OPs, CMs contain an electrophilic carbonyl carbon, which undergoes nucleophilic attack by the active. site. serine oxygen (Fig. 2). The resulting carbamylatcd enzyme intermediate inhibits enzyme activity until a water molecule attacks the carbonyl carbon to reactivate enzyme and produce a carbamic acid derivative (Fig, 2). This rate of reactivation is considerably faster than that of phospylated enzyme, although it is not as rapid as reactivation of the acetylated intermediate. 

By treatment with gaseous CO2, a layer containing the amino derivative (X = NH) exhibited new signals at 1560 and 1540 cm in the infrared spectra due to formation of carbamic acid derivatives [7] (Scheme 4). By treating a cured layer containing the thioether moiety (X = S) with gaseous SO2 a new signal at 320 nm was observed by UV-Vis spectroscopy this is attributed to the formation of a thioether/S02 adduct [8] (Scheme 4). 

Derivatization has also been applied to generate UV-absorbing compounds from amphetamines [27]. The reagent used was FMOC, which reacts with primary and secondary amines to form derivatives which provided selective and sensitive UV detection during packed column SFC with modified COj as mobile phase. David and Sandra noted [28] that COj is able to react with amines at elevated temperatures and pressures to give carbamic acid derivatives insoluble in supercritical CO2. Formation of the trifluoroacetyl derivatives, however, gave excellent peak shapes in capillary SFC for a variety of Cift-Cii amines with COj mobile phase and FID. 

Carbonyl azides react with alcoholic hydroxy compounds to form the corresponding urethanes. In the same manner, ferrocenoyl azide, and 3-fe-rrocenylpropionyl azide can derivatized, hydroxy-steroids and the resultant derivatives are determined electrochemically by LC with the detection limits at subpicomole levels. 2-[2-(Azidocarbonyl)ethyl]-3-methyl-1,4-naphthoquinone (AMQ) reacts with primary and secondary alcohols to produce carbamic acid derivatives and is used in LC with BCD and FL detections. 7-Methoxycoumarin-4-carbonyl azide (7-MC-4-CON3) and 3,4-dihydro-6,7-dimethoxy-4-methyl-3-oxoquinoxaline-2-carbonyl azide (DMEQ-CON3) are also applied to LC with FL detection as precolumn reagents. 

The following chemical reaction takes place the water reacts with the isocyanate end groups of the prepolymer to form a carbamic acid derivative. This is converted into an amine by the elimination of carbon dioxide (CO2) and is then cross-linked with a fiorther isocyanate group to form a polyurea (Fig. 54). 

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