Carbanilates

The acetyl content of cellulose acetate may be calculated by difference from the hydroxyl content, which is usually determined by carbanilation of the ester hydroxy groups in pyridine solvent with phenyl isocyanate [103-71-9J, followed by measurement of uv absorption of the combined carbanilate. Methods for determining cellulose ester hydroxyl content by near-infrared spectroscopy (111) and acid content by nmr spectroscopy (112) and pyrolysis gas chromatography (113) have been reported. 

The ether extract is separated, dried over sodium sulfate, and evaporated to an oily residue (40 g) which contains ethyl o-(p-chlorophenoxy) carbanilate and is used without further purification. The crude ethyl o-(p-chlorophenoxy)carbanilate is dissolved in 20 ml of benzene, and 20 ml of 1-methylpiparazine and a small amount of sodium methylate (approximately 25 to 50 mg) are added. Benzene is then removed by slow distillation and the mixture is heated overnight under reflux (approximately 16 hours). 

Phenylcarbamates, or carbanilates, generally exhibit low water solubilities, and thus they are almost immobile in soil systems. Chlorpropham and Propham are readily volatilized from soil systems, but Terbutol and Carbaryl (Fig. 10, Table 3) are not. Ester- and amide-hydrolysis, N-dealkylation and hydroxylation are among the chemical reactions that carbamates undergo. The N-methylcar-bamate insecticides (Fig. 10, Table 3) commonly used in soils are Carbaryl, Methiocarb,Aldicarb,and Carbofuran [74,173]. 

The photocatalytic degradation of widely used herbicides such as 2,4-D (2,4-dichlorophenoxyecetic acid), 2,4,5-T (2,4,5-trichlorophenoxyacetic acid), bentazon (3-isopropyl-1 H-2,l,3-benzothiadiazin-4(3H)-one 2,2-dioxide), S-tiazines, carbetamide ((R)-l-(ethylcarbamoyl)ethyl carbanilate), and monouron (3-(4-chlorophenyl)-l-methoxy-l-methylurea) in water have been... 

Carbanilic acid and derivs 2 C43—C44 carbanilic acid azide 2 C43 trinitrocarbanilic acid esters 2 C43-C44... 

Another carbanilate herbicide, 4-chloro-2-butynyl 3-chlorocarbanilate (barban), formed a water-soluble metabolic product in various plants. The metabolite could not be identified as any simple reaction-product, and it was tentatively proposed that the original herbicide might be associated with a plant component such as a flavonoid. 3-Chloroaniline could be distilled out after hydrolysis, and several hydrolytic fractions contained carbohydrates but no nitrogen.177... 

Carbanilic Acid or Pbenylcarbamic Acid(called Carbanilsaure Phenylcarbamidsaure or Anilinoameisensaqre in Ger), CgHg.NH.COOH mw 137.13, N 10.21% exists in the form of salts other derivs, some pf which are expl Ref Beil 12, 319, (218) [l84]... 

Trinitrocarbanilic Acid Ethyl Ester or Picryiurethane(called 2.4.6-Trinito-carbanilsaure -athylester or Pikrylurethan in Ger), (02N)3C6H2.NH.C00.C2Hs mw 300.19, N 18.67% It yel ndls (from dil ale) ot pltls(from coned ale), mp 144-47° can be prepd by nitration of carbanilic acid ethyl ester or of mono- dinitroderivs and by other methods. Its expl props were not reported Ref Beil 12, 768, (370) [423]... 

The thermolysis of ethyl azidoformate in excess azobenzene at 115-117°C gives, as the major product, ethyl 2-(phenylazo)carbanilate the proposed reaction mechanism suggests the formation of an azimine (8) (by attack of the nitrene on the azo group) which rearranges to the carbanilate via a bicyclic A3-triazoline ring system,18 apparently formed by a 1,5-electrocyclization19 of 8 (Scheme 4). 

Oxidizing Effects of Carbanilation Mixtures Containing DMSO. 191... 

The final section addresses degradation and oxidation reactions in a commonly used derivatization system for cellulose, a mixture of DMSO and phenyl isocyanate to achieve cellulose carbanilation, e.g. for analytical purposes. Mechanistic studies were aimed at verifying the assumed oxidative action of this reaction system, and trapping methodology was employed to detect responsible intermediates. 

It was the main goal of our studies to verify the existence of an oxidizing effect of DMSO-based carbanilation mixtures on cellulose, and - if this effect existed - to clarify the responsible reactive intermediates. Trapping reactions were again the key elements in these mechanistic studies. 

The oxidative power of carbanilation mixtures containing DMSO and isocyanates was concluded from cellulose degradation in these mixtures. The mechanism of cellulose degradation was proposed to be a combination of oxidation and subsequent chain cleavage at the oxidized positions according to a /3-elimination mechanism triggered by auxiliary bases [ 106]. 

Indeed, the oxidizing effect of a DMSO/PhNCO mixture under standard cellulose carbanilation conditions, i.e. reaction times of 2-3 d at tem-... 

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