摘要:
Chemical Corn m u n i cat ions NUMBER 12/1965 23 JUNE Trifluoromethyl Fluoroformate By P. J. AYMONINO (Instituto Superior de Investigaciones, Facultad de Quimica y Farmacia, Universidad Nacional de La Plata, Argentina) LOW-TEMPERATURE fractionation of the products of the photochemical reaction between trifluorome- thoxyl fluoridel and a slight excess of carbon monoxide gave high yields (86%) of a new sub- stance with the analytical and molecular-weight properties expected for trifluoromethyl fluorofor- mate. The irradiations were performed at 35" in a quartz vessel with U.V. light from a Q 700 lamp (Quarzlampen Gesellschaft m.b.H., Hanau, Ger- many), filtered through the Pyrex wall of a water bath. The pressure decrease during the reaction was slightly less than the initial pressure of trifluoromethoxyl fluoride.Minor products were carbonyl fluoride, carbon dioxide, silicon tetrafluoride, and a substance ( M , 310), not yet identified, but apparently containing six fluorine atoms per molecule and showing in the infrared spectrum (gas) carbonyl stretching (maxima at 1842 and 1828 cm.-l) and other bands assignable to C-F and C-0 stretching vibrations and deformations. Trifluoromethyl fluoroformate melts near - 120" ; its vapour pressure obeys the equation: logp (mm.) = 8.701-1380/T (OK) between -50 and - 100 OC. The extrapolated boiling point is -36" and latent heat of vaporization 6.3 kcal./mole. The infrared spectrum of the gaseous substance at low pressure (NaC1 optics) shows strong absorp- tion maxima in the carbonyl(l906 and 1901 cm.-l), C-F (1296, 1260, and 1174 cm.-l) and G O (1026 and 1021 cm.-l) stretching regions, in addition to other weaker peaks at lower frequencies (768, 677, 672, and 655 cm.-l), assignable to deformations.The spectrum appears as a combination of those of trifluoromethoxyl fluoride,2 bistrifluoromethyl per- oxide,3 and bisfluoroformyl peroxide.3 Trifluoromethyl fluoroformate decomposes on strong heating in a quartz vessel producing carbonyl fluoride, silicon tetrafluoride, carbon dioxide, and carbon tetrafluoride. Experiments with trifluoromethoxyl fluoride alone or mixed with carbonyl fluoride [main reaction product : bistrifluoromethyl peroxide] under the same experimental conditions show that the photodissociation of trifluoromethoxyl fluoride is a slow reaction. Therefore, the formation of trifluoromethyl fluoroformate, which is faster than the former reaction, should be a chain reaction involving F,C.OCO- radicals. Interaction between trifluoromethoxyl fluoride and carbon monoxide did not take place in the dark at 35" but at 90°, for instance, an equimolecular mixture (total pressure 400 mm.) reacts with maximal rate of pressure decrease of 1-3 mm./min. (Received, March 29th, 1965.) 1 K. B. Kellogg and G. H. Cady, J . Amer. Chem. SOL, 1948,70, 3986. 8 A. J. Arvia and P. J. Aymonino, Seectrochim. Acta, 1962, 18, 1299. R. T. Lagemann, E. A. Jones, and P. J. H. Woltz, J . Phys. Chem., 1952,20, 1768.
ISSN:0009-241X
DOI:10.1039/C19650000241
出版商:RSC
年代:1965
数据来源: RSC