Sulfur-containing carbamates

Closely related are the syntheses from various sulfur-containing derivatives of 2-pyridylhydrazine by which it is possible to obtain the 3-thiol (or thione) 6180 or 3-methylaminotriazolopyridine (62).88 By use of dithio-carbamates instead of acylhydrazines, the iminoether synthesis gives the tetrahydrotriazolopyridine-3-thiol (or thione) 63.89-92 Cyclization of the amidine 64 gives 3-anilinotriazolopyridine (65).93... 

Carbamate pesticides can be determined using different detectors in GC or HPLC analysis. A characteristic feature of a carbamate molecule is the nitrogen atom, which can form the bases for quantitation and some carbamates also contain chlorine, sulfur, or other heteroatoms in the molecule. This allows the use of various detection techniques for their determination (139,140), such as electrical conductivity (165), alkali flame (141) photometry, and mass spectrometry (44,166). 

Similarly, on-column methylation has been applied to carbamate pesticides containing an active N-H group. Wien and Tanaka (41) showed that N-aryl carbamates are methylated on-column with tri-methylanilinium hydroxide-methanol to give the intact N-methyl and N-aryl derivatives. On the other hand N-methyl, 0-aryl carbamates such as carbaryl or carbofuran yielded only the methyl ethers of their respective phenols. This work has now been extended to sulfur-containing carbamates such as methomyl, methio-carb, aldicarb, etc. (42-43). Here the oxime hydrolysis products of these carbamates are chromatographed as the 0-methyl oximes. 

The advantageous biological properties of aldicarb stimulated a search for further oxime carbamates which contain a sulfide-sulfur atom as an electronegative part of the molecule. 

To 40 mL of the above solution of crude fluorodinitroethylcarbamoyl chloride 626, 2-fluoro-2,2-dinitroethanol 630 (5.6 g) was added, followed, dropwise and with cooling in an ice bath, by pyridine (3.1 g). The mixture was stirred at room temperature for 2 h, diluted with dichloromethane (100 mL), washed with dUute sulfuric acid, dried, and concentrated. Repeated chilling, filtration, and concentration of the mother liquor gave several fractions of N,0-his(2-Jluoro-2,2-dinitroethyl)-carbamate 631 containing diminishing amounts of N,N -bis(2-fluoro-2,2-dinitro-ethyl)urea as an impurity. The yield of crude product amounted to 3 g. The product was purified by recrystallization from dichloromethane/hexane mp 63-64 °C. 

Poly(ethylenimine S-alkyldithiocarbamate) polymers were prepared from respective poly(ethylenimine sodium dithiocarbamate) and alkyl chlorides, aralkyl chlorides, substituted alkyl esters of chloroacetic acid, p-chloroethyl esters of carbamic and carboxylic acids, and N-substituted chlorocarboxamides. The derivatives thus obtained were decomposed both physically and chemically to release sulfur and sulfur-containing substances which acted as controlled-release herbicides or fungicides. One author has proposed reactions of the pesticide 2,6-dichlorobenzaldehyde with diols and amines to form polyamide polycondensation products. ... 

Amine Cross-Linking. Two commercially important, high performance elastomers which are not normally sulfur-cured are the fluoroelastomers (FKM) and the polyacrylates (ACM). Polyacrylates typically contain a small percent of a reactive monomer designed to react with amine curatives such as hexamethylene-diamine carbamate (Diak 1). Because the type and level of reactive monomer varies with ACM type, it is important to match the curative type to the particular ACM ia questioa. Sulfur and sulfur-beating materials can be used as cure retarders they also serve as age resistors (22). Fluoroelastomer cure systems typically utilize amines as the primary cross-linking agent and metal oxides as acid acceptors. 

Chapter 5 Compounds which contain either an ester or an amide link in a single macrocyclic ring. This includes lactones, lactams, carbonates, carbamates, ureas, phosphates, etc. including sulfur, nitrogen and other atoms in the ring. 

A more conventional route is the acid-catalyzed cyclodehydration of amides already containing the appropriate numbers of atoms. For example, carbamates (213) may be cyclized to oxazinediones (214) with concentrated sulfuric acid (76JCS(Pl)1969) and the dihydrobenzoxazin-4-ones and -thiazin-4-ones (216) can be prepared from the appropriate benzamides (215), again by treatment with acidic reagents (53AP437). 

Elemental selenium is an excellent catalyst for fhe carbonylation of a variety of nucleophiles such as amines, alcohols, water, and carbon nucleophiles in the presence of oxygen under mild conditions [114]. In fhe synfhesis of ureas from primary amines and CO, for example (Scheme 15.42), the turnover number reaches ca. 10", giving ureas in almost quantitative yields. Successful applications of this Se/CO system include not only synfhetic reactions with a variety of carbamates, carbonates, and sulfur- or selenium-containing compounds but also metallurgical refining of selenium and several important processes as exemplified by isocyanate synfhesis, fhe water-gas shift reaction, and separation of carbon monoxide [115]. 

OP insecticides having phosphonate and carbamate structure that contain thioether bonds are good substrates for FMO. These enzymes participate in oxidative desulfuration (P=S P=0) of OPC such as fonofos and phenylfonofos [22, 23]. It has been shown that FMO requires P-C bond in OPC since it acts directly on phosphorus atom, while oxidative desulfuration with P450 occurs on sulfur that is bound to phosphorus (P=S). For that reason parathion and some phosphorodithionates are not FMO substrates. Compounds of trivalent phospho-... 

In addition to cytochrome P450s, hepatic microsomes contain another class of mono-oxygenases, the flavin-containing mono-oxygenases (FMO). These enzymes catalyse oxidation at nucleophilic nitrogen, sulfur and phosphorus atoms rather than oxidation at carbon atoms, e.g. for phenothiazines, ephedrine, norcocaine and the mono-ether and carbamate-containing pesticides. 

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