63- 25-2 Carbaryl

The poisoning effects from carbaryl take place very quickly, but lasts only for a short time. It is readily hydrolyzed to 1-naphthol which is excreted. Although its toxicity in hnmans is relatively low, the compound can prodnce strong effect on bees and aquatic species even in small quantities. 

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Environmental. The A/-methylcarbamates generally are biodegradable and of low soil persistence with half-Hves for carbaryl and aldicarb of 1—2 weeks and of carbofuran of 1—4 months. Certain carbamates are highly toxic to birds with oral LD qS for mallard, eg, pheasant, in mg/kg carbofuran, 0.40, 4.2 mexacarbate, 3.0, 4.5 and methomyl, 16, 15 compared to carbaryl >2000. Fish toxicity of carbamates is generally low, but these compounds are extremely toxic to bees. In cases of human poisoning, atropine is a specific antidote. 

Another large use of naphthalene is as a raw material for the manufacture of 1-naphthyl-A/-methylcarbamate [63-25-2] (carbaryl, Sevin). Cmde or semirefined coal-tar or petroleum naphthalene can be used for carbaryl manufacture. Carbaryl is used extensively as a replacement for DDT and other products that have become environmentally unacceptable (see InsectcontrolTECHNOLOGY). 

Naphthol is mainly used in the manufacture of the insecticide carbaryl (59), l-naphthyl A/-methyicarbamate/ iJ-2j5 - (Sevin) (22), which is produced by the reaction of 1-naphthol with methyl isocyanate. Methyl isocyanate is usually prepared by treating methylamine with phosgene. Methyl isocyanate is a very toxic Hquid, boiling at 38°C, and should not be stored for long periods of time (Bhopal accident, India). India has developed a process for the preparation of aryl esters of A/-alkyl carbamic acids. Thus l-naphthyl methylcarbamate is prepared by refluxing 1-naphthol with ethyl methylcarbamate and POCl in toluene (60). In 1992, carbaryl production totaled > 11.4 x 10 t(35). Rhc ne-Poulenc, at its Institute, W. Va., facihty is the only carbaryl producer in United States. 

Carbamate hydrolysis is frequendy observed as the initial reaction for pesticides having carbamate bonds, such as aldicarb, carbofuran, carbaryl, and benomyl (eq. 12) (19). Numerous genera of carbamate-hydroly2ing bacteria have been identified, including Pseudomonas, Jhihrobacter, Bacillus, Nocardia, Achromobacter, Flavobacterium, Streptomyces, Alcaligenes, A spirillum, Micrococcus, and Bhodococcus. 

High performance Hquid chromatography with electrochemical detection has been used to determine 2—7 ppb of carbamate pesticides in water (40). The investigated pesticides were aminocarb, asulam, j -butylphenyknethylcarbamate (BPMC), carbaryl, carbenda2im, chlorpropham, desmedipham, and phenmedipham. 

Atrazine, carbofuran, carbaryl, esfenvalerate, imidazole fungicides Industrial chemicals... 

Carbamates and dithiocarbamates (carbofuran, carbaryl, ziram, and benthiocarb)... 

The insecticide carbaryl can be produced by several routes, some of which do not use methyl isocyanate, or which generate only small quantities of this toxic material as an in-process intermediate (Kletz, 1991b). One company has developed a proprietary process for manufacture of carbamate insecticides which generates methyl isocyanate as an in-situ intermediate. Total methyl isocyanate inventory in the process is no more than 10 kilograms (Kharbanda and Stallworthy, 1988 Manzer, 1994). 

Oxygen -I- Methyl Formamide-1- a—Naphthol = Carbaryl + Water (12.2) which yields an economic potential of 39.99 million per year, and... 

Methyl Amine + a-Naphthol Chloroformate = Carbaryl -I- Hydrogen Chloride,... 

The product, carbaryl, was manufactured by reacting phosgene and methylamine to produce MIC, which was then reacted with alpha-naph-thol. The same product can be made from the same raw materials by reacting them in a different order and avoiding the production of MIC. Phosgene is reacted with alpha-naphthol, and then the intermediate is reacted with methylamine. 

CAPTAN SC , captan, 35 Carbachol chloride, 35 Carbagas, 156, 203 Carbamic acid ethyl ester, 35 Carbaryl, 35... 

Two major chenucal reactions dominate llie meiliyl isocyanate (MIC) reaction to form carbaryl tliat were occurring in ilie Bhopal pkuit. Briefly describe these two reactions. 

A practical application of SEE-CEST coupling is shown in Eigure 6.13, which displays the electropherogram obtained for a tomato sample contaminated with a pesticide, i.e. carbaryl. The sample was placed in the SEE cell, extracted with CO2... 

Figure 6.13 SEE-MEKC electropherogram of the pesticide carbaryl in a tomato sample the peak assigned number (4) coiresponds to the migration time of carbaryl. (from ref. 58).

The detection limits for catecholamines are 10 to 50 ng substance per chromatogram zone [11] and 50 ng substance per chromatogram zone for carbaryl and a series of other... 

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