Dimethyl dicarbamate

In certain cases, the FDA has applied a negligible risk concept for food additives. This is demonstrated in the case of dimethyl dicarbamate, a yeast inhibitor for use in beverages (FDA 2000). The additive evenmaUy decomposes to methanol and carbon dioxide, but in the presence of ammonium ions (not uncommon in certain beverages) a carcinogenic chemical may also be formed in small amounts. The FDA used formal quantitative risk assessment procedures to estimate the upper-bound limit of carcinogenic risk to humans posed by urethane generated by decomposition of the additive. It was concluded that the potential risk was sufficiently low that the additive would be safe for the requested use, and the FDA s final rule approved its use (56 FR 40502 1988). 

Having assembled the bicyclic framework, attention was directed toward introduction of the diylophile. Deprotection of the masked aldehyde in 46 and 47 was most efficiently accomplished using 70% aqueous acetic acid at 50-60 °C for 5 days (85% and 95% yield, respectively). The dimethyl dicarbamate was subjected to saponification with potassium hydroxide in refluxing ethanol for 1.5 hours, whereafter the in situ oxidation with potassium ferricyanide at 0 °C gave rise to the dizaene 48 in yields ranging from 76-86%. We were gratified to observe that treatment of 48 with triphenylphosphonium methylide in THF at room temperature led to the desired diyl precursor 41 in 56-83% yield. 

Chemicel Name Dimethyl) [2-(2.methoxyacetamido)-4.phenylthiophenyl]-imidacarbony ] -dicarbamate... 

The second objective of this study is to determine the feasibility of using diphenyl phosphinic acid as a catalyst for synthesis of dimethyl 4-methyl-1, 3-phenylene dicarbamate (DMPD) from 2, 4-diaminotoluene and DMC (step 6) as follows ... 

Azo compounds. A mild new synthesis of azo compounds from dicarbamates (prepared by Diels-Alder reactions with dimethyl azodicarboxylate) involves cleavage with LiSCHs to form a dilithium dicarbamate followed by oxidative didecarboxylation with K, Fe(CN)g at 0°. 

In this method, dimethyl carbonate (DMC) is reacted with IPDA to afford isophorone dicarbamate (IPDC). The IPDC is decomposed in the liquid phase in a high-temperature boiling solvent under reduced pressure to give high yields of IPDI. 

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