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    • 4. 发明专利
    • NL144304B
    • 1974-12-16
    • NL6607233
    • 1966-05-25
    • BAYER AG
    • C08G8/28C08G73/06C08G5/18C08G15/02C07C119/04
    • Phenolic resins are converted into their cyanate esters by reaction with cyanogen chloride or bromide in water or an inert organic solvent i.p.o. a base which is present throughout the reaction in an amount less than that equivalent to the cyanogen halide added. Suitable resins are novolak and resole resins, and also adducts of phenols and e.g. vinyl ethers. Preferred are novolak resins of 600-1500 molecular weight. The base may be an alkali metal hydroxide, carbonate, bicarbonate, alcoholate, an alkaline earth metal hydroxide, or a tertiary amine, e.g. NaOH, KOH, Ca(OH)2, Ba(OH)2, NaHCO3, Na2CO3, K2CO3 Li2CO3, NaOCH3, trimethylamine, triethylamine, tripropylamine and diethylcyclohexyl amine. Suitable solvents are alcohols, ketones, ethers, esters, nitriles, amides, sulphoxides, sulphones and aromatic and aliphatic hydrocarbons, which may be nitrated or halogenated, and water. Mentioned are MeOH, EtOH, acetone, Et2O, MeCN, ethyl acetate, dimethyl formamide, benzene, petroleum ether, nitrobenzene, nitromethane, CHCl3, CCl4, chlorobenzene, and dimethylsulphoxide. The reaction may be conducted between - 30 DEG and 70 DEG C. In examples, novolaks from phenol and from p-t-butylphenol and formaldehyde, and a resorcinol/formaldehyde condensate are reacted in acetone i.p.o. triethylamine with cyanogen chloride or bromide equivalent to all or part of the OH groups of the resin.