| 摘要 |
1,220,851. Production of #-lactones. MITSUBISHI CHEMICAL INDUSTRIES Ltd. 16 Jan., 1968 [27 Jan., 1967; 4 Nov., 1967; 21 Dec., 1967], No. 2386/68. Heading C2C. #-Lactones of the Formula I wherein R 1 and R 2 are each C 1 -C 4 alkyl are prepared by contacting a carboxylic acid of formula wherein R 1 and R 2 are as before and X is halogen, hydroxy or C 1 -C 6 aliphatic acyloxy, at elevated temperature and subatmospheric pressure, with a catalyst which is at least one metal compound or a boron compound in solution or suspension in a liquid reaction medium which is the said carboxylic acid or an inert organic medium having a boiling point higher than the said #-lactone, to eliminate a compound of formula HX and produce the required #-lactone, the weight of catalyst remaining substantially unchanged during the course of the reaction. The catalyst may be an organic or inorganic acid salt, oxide, hydroxide, hydrated oxide or co-ordination compound of a metal of Groups I to VIII or boron. Typical metals are Al, Li, V, Cr, Ti, Mn, Li, Ba, Zr, Sn, Bi, Mn, Co, Na, K and Hg; preferred compounds are boric acid and chromium acetate. An inert gas, e.g. nitrogen, may be passed through the reaction mixture, the #-lactone and the by-product HX distilling over with the inert gas. The pressure may be 0.1 to 500 mms. Hg and the temperature from 100‹ to 350‹ C. Reference has been directed by the Comptroller to Specifications 1,104,183, 1,145,589 and 1,135,820. |
