NaBrO3 combined with NaHSO3 was found to be an excellent oxidizing reagent of alcohols, diols, and ethers under mild conditions. A variety of aliphatic and cyclic diols were selectively oxidized with satisfactory yields to the corresponding hydroxy ketones and/or diketones, which are difficult to selectively prepare due to a concomitant formation of cleaved products. For example, 2-hydroxycyclohexanone and 1,2-cyclohexanedione were selectively formed by allowing 1,2-cyclohexanediol to react with NaBrO3/NaHSO3 reagent in a selected solvent. On the other hand, an alkyl ether, such as dioctyl ether, reacted with NaBrO3/NaHSO3 in water at room temperature to give octyl octanoate in 82% yield. The same oxidation at higher temperature (60 °C) produced the α-brominated ester, octyl 2-bromooctanoate, which is considered to be formed through an alkenyl alkyl ether as the intermediate. The treatment of 1-ethoxy-1-heptene with NaBrO3/NaHSO3 afforded ethyl 2-bromoheptanoate and 2-bromoheptanoic acid as the major products.
Coating compositions stabilized against damage by light, heat and oxygen
申请人:Ciba Specialty Chemicals Corporation
公开号:US06706215B1
公开(公告)日:2004-03-16
Coatings comprising
A) a binder based on an organic polymer and
B) as stabilizer against damage by light, heat and oxygen, a 2-(2′-hydroxyphenyl)-1,3-pyrimidine of the formula I
in which the radicals R1 to R6 are as defined in claim 1 have an outstanding resistance to the damaging effects of light, oxygen and heat. Compounds of the formula Ib defined in claim 18 are suitable in general for the stabilization of organic material.