Carbamates, N-methyl

Determination of Aldicarb and other N-methyl carbamates in Waters (by HPLC or Confirmation of total Aldicarb residues and other N-methyl carbamates in waters by GC), 1994... 

After having been cooled it is washed three times in water, three times in a 5% solution of caustic soda, and then another three times in water. The solution in xylene is dried over sodium sulfate and the xylene is completely distilled off in vacuo. Thus 11.0 parts of hexa-methylene-bis-(N-methyl carbamic acid-3-pyridyl ester) are obtained. 

Soils treated with Carbamyl and Carbofuran have been analysed by gas chromatography following conversion of N-methyl carbamates to their pentafluorobenzyl derivatives [84],... 

Conditions-. Reflux temperature. 90°C Amine/Base/DMC molar ratio 1/1.2/40. AfterlSh, 73% of N-methyl carbamate. 

The general chemical structure of N-methyl carbamate is shown in Fig. 4.4. Common N-methyl carbamates in use today include aldicarb, carbofuran, methiocarb, oxamyl, and carbaryl. N-methyl carbamates share with organophosphates the capacity to inhibit cholinesterase enzymes and, therefore, share similar symptomology during acute and chronic exposure. 

The N-methyl carbamate esters cause reversible carbamylation of the acetylcholinesterase enzyme, allowing accumulation of acetylcholine, the neuromediator substance, at parasympathetic neuroeffector junctions (muscarinic effects), at... 

It tends to limit the duration of N-methyl carbamate poisoning. 

N-methyl carbamates are absorbed by inhalation and ingestion, and somewhat by skin penetration, although the last tends to be a less toxic route. 

Figure 1. Plot of obsd for ring closure of phenyl N-(2-hydroxyphenyl)-N-methyl carbamate to N-methyl-2 benzoxazolinone and phenoxide ion at 25° in H O with m - 0 5 M (with KCl).

Pyridinol carbamate has been used as an anri-inflammatory/anti-arteriosderotic. This compound 2,6-pyridinedimethanol-bis-(N-methyl carbamate) is also known as Anginin. See rhe formula below1. 

Ethyl N-benzylcarbamate and its nitroso compound have been prepared by methods similar to those described for ethyl N-methylcarbamate and its nitroso compound.2 3 2-Phenylcyclo-heptanone has been prepared by the reaction of ethyl N-nitroso-N-benzylcarbamate4 with cyclohexanone,5 by the reaction of phenyldiazomethane with cyclohexanone,6 by the reaction of ethyl N-nitroso-N-methyl carbamate with 2-phenylcyclohexa-none,6 and by the rearrangement of l-phenyl-2-cyclohexylethylene oxide.7... 

N 36.84%, OB to CO, -42.1%. Ndls(from ether), mp 38°, d 1.2433 at 48.6°, nD 1.46162 at 48.6°(Ref 2) expl violently when heated in a capillary(Ref 3) Easily sol in w, ale, chlf benz less sol in eth very si sol in petr eth. Was first prepd by Franchi-mont Klobbie(Ref 2) by nitration and hydrolysis of methyl-N-methyl-carbamate, CH,COa NH-CHj. Other methods are known (Refs 1 4). Johnson(Ref 5) prepd it in 66% yield by nitration and hydrolysis of ethyl-N-methyl-carbamate-. Detailed description of procedure is given. It is a powerful expl, with a Trauzl test value of 144%PA. Its toxicity is probably similar to that of amino-methane(qv)... 

In California, mixer-loaders and spray applicators who work with toxicity category I and II organophosphates or N-methyl carbamates more than 30 hours per 30-day period are required to have medical supervision. Supervision consists of an interview and a medical examination to determine if a medical condition exists which would make the worker unusually susceptible to poisoning due to cholinesterase inhibition, and to caution the individual about the use of certain drugs such as the pheno-thiazine tranquilizers vdtich potentiate the effects of cholinesterase (ChE) inhibition. Two blood samples, taken several days apart, are analyzed to determine the individual s preexposure plasma and red blood cell (RBC) ChE activity (baseline value). The physician arranges a routine ChE testing program and provides for extra ChE tests should the worker be accidently exposed to OP s. If ChE activity is depressed to 50 percent of the baseline value, the physician may ask the employer to place the worker on... 

Studies on the Effectiveness of Closed-Transfer Systems for Mixing and Loading Toxicity Category I and II Products Containing Organophosphates and N-methyl Carbamates... 

Work Item D determination of N-methyl carbamate residues. 

A solution of 11.9 parts of m-dimethylaminophenol in 90 parts of xylene (isomer mixture) is added to a solution of sodium methylate consisting of 2.0 parts of sodium and 25 parts of methanol. The methanol is then completely removed by distillation and the temperature raised until the boiling point of the xylene is reached. The decamethylene-bis-(N-methyl carbamic chloride) is added to the remainder which contains the sodium salt of m-... 

---