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The anion of 2-(2-nitroethyl)-l,3-dioxolane (4), prepared from the corresponding 2-bromo compound (3), undergoes condensation with acylimidazoles to give the 3-nitro-4-oxobutanal acetals (9), which can serve as valuable polyfimctional intermediates. Condensation with l-(methoxyoxalyl)imidazole gives the tetrafunctionalized methyl 4-(l,3-dioxolan-2-yl)-3-nitro-2-oxobutanoate (13), which, however, decomposed on attempted deprotection of the ester function. The syntheses in excellent yields of simple -nitro ketones and -nitro esters from acylimidazoles and nitroethane and 2-nitropropane are also described. 100-14-1; 2-(2-chloro-2-nitroethyl)-2-chloro-l,3-dioxolane, 82892-17-9.

Tropospheric lifetimes and ozone-depletion potentials (ODPs) are estimated for all 53 possible one-and twocarbon hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs). The relationships among C-H bond strength, activation energy for removal of H by OH, tropospheric lifetime, and ODP are examined. Algorithms are developed that are easy to apply and accurate enough for initial screening purposes. On the basis of extant theory and our analysis, the controlling variables for determining HCFC tropospheric lifetimes include number of hydrogen atoms, molecular weight, number of carbons, number of chlorine atoms a and ß to hydrogen, and number of fluorine atoms ß to hydrogen. The formula presented predicts lifetimes for molecules with atmospheric lifetimes below 30 years with a root mean square (rms) error of a factor of 2.4. An algorithm is also presented to calculate ODP based on tropospheric lifetime; the overall rms error for calculating ODP from the structure is a factor of 2.5. In many cases, ODPs of chlorine-containing compounds are predicted to be below 0.001. These estimates also aid in making tentative choices among alternative HFCs and HCFCs based on environmental considerations.

Sandia is a multiprogram laboratory operated by Sandia Corporation, A Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.

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