Untitled

Abstract

A combined study of the OH gas phase reaction and uptake on aqueous surface of two carbonates, dimethyl and diethyl carbonate has been carried out to determine the atmospheric lifetimes of these compounds. Rate coefficients have been measured for gas phase reactions reported data show that the OH reaction is the major atmospheric loss process of these two carbonates with lifetimes of 33 and 5 days, respectively, while the wet deposition is a negligible process.

Reactivity of ditert-butyldimethoxystannane with carbon dioxide and methanol: X-ray structure of the resulting complex

“…The third one had characteristic resonances at d Sn À113 with 2 J 119 Sn, 117 Sn value of 928, d C-ðCH 3 Þ 3 at 38.86 ( 1 JC-119,117 Sn = 497, 475) and d OCH 3 at 53.90. Bearing methoxy ligands, this specie is tentatively assigned to the distannoxane [tert-Bu 2 (CH 3 O)Sn] 2 O that disproportionates to some extent in solution giving 1 and (tert-Bu 2 SnO) 3 . Precedents on the instability of other distannoxanes in the tert-butyl series can be found in the recent literature [19].…”

“…The 13 C{ 1 H} spectrum revealed three signals for the Sn-C and CCH 3 carbons, respectively, and two methoxy resonances at d 54.71 and 53.90. Accordingly, two species have been identified as 1 and (tert-Bu 2 SnO) 3 . The third one had characteristic resonances at d Sn À113 with 2 J 119 Sn, 117 Sn value of 928, d C-ðCH 3 Þ 3 at 38.86 ( 1 JC-119,117 Sn = 497, 475) and d OCH 3 at 53.90.…”

“…However, dimethyl carbonate (DMC) has low toxicity, rapid biodegradability [2], low impact on air quality [3], and new applications are foreseen in different sectors (e.g., polymers, fuels, organic synthesis) [4] provided friendly processes are available for its production. Accordingly, the three synthetic approaches currently under active scrutiny are: (i) carbonate transesterification, (ii) urea methanolysis, and (iii) methanol carbonation [5].…”

Viscosities of dimethyl carbonate with alcohols at several temperatures

“…Organic carbonates have been suggested as fuel additives because their use may reduce the vapour pressure of fuels and in turn reduce their emissions to the atmosphere by evaporation [1]. DMC has about three times the oxygen content that MTBE this fact focus it as a strong contender to help the refining industry.…”

Synthesis of Linear and Cyclic Carbonates

“…Yet, today, DMC production is expanding rapidly in other countries, with China forecasting a production capacity in the range of 20 000 tons [16] . Currently, much attention is being focused on DMC applications due to its low toxicity, an absence of any irritant or mutagenic effects, its high biodegradability [17] , and low atmospheric loss [18] . Consequently, DMC is today considered as a chemical feedstock that fulfi ls the " green " chemistry and engineering criteria [19,20] that are aimed at handling safer chemicals, and at selecting the safest and most effi cient way in which to synthesize those chemicals.…”