摘要:
Alkylisothiocyanic acid esters having the formula R--N.dbd.C.dbd.S can be prepared by reacting N-alkyldithiocarbamates with hydrogen peroxide in aqueous phase at 95.degree. to 130.degree. C. The aqueous solution of N-alkyldithiocarbamate is reacted with a 20 to 40% by weight aqueous solution of hydrogen peroxide in a volumetric ratio of 1 to 0.8 to 1 while maintaining a pH of 1.5 to 4.5. The solutions are preferably sprayed into a reactor, at which time the alkylisothiocyanate formed distills off in vapor form and an aqueous phase containing the byproducts collects in the reactor. The method is capable of significantly increasing the space-time yield because much less sulfur is formed in comparison to the previously known method, which takes place at pH 5 to 9, thereby minimizing the shutdown times previously required for cleaning the reactor.
摘要翻译:具有式RN = C = S的烷基异硫氰酸酯可以通过N-烷基二硫代氨基甲酸酯与过氧化氢在95〜130℃的水相中反应来制备。N-烷基二硫代氨基甲酸酯水溶液与20〜40重量% 过氧化氢水溶液,其体积比为1至0.8至1,同时保持pH为1.5至4.5。 溶液优选喷雾到反应器中,此时形成的异硫氰酸烷基酯以蒸气形式蒸馏出来,含有副产物的水相收集在反应器中。 与先前已知的在pH5至9下进行的方法相比,该方法能够显着增加空时产率,因为形成的硫少得多,从而使先前清洗反应器所需的关机时间最小化。
摘要:
A quantitative enrichment of volatile compounds from substances of the macro- to submicro field in a short time is realized by capillary distillation in a system which includes an evaporator vessel, on the bottom of which one or more filter plates are provided and which is connected to a condensing vessel by means of a capillary tube. The presence of filter plate(s) guarantees a uniform and constant boiling which facilitates the quantitative isolation of the volatile compounds.
摘要:
Methyl isocyanate is prepared by reacting an alkali cyanate with dimethyl sulfate in the presence of an alkaline earth metal oxide and in an inert organic liquid. There can also be present an alkali metal or alkaline earth metal salt.
摘要:
Isothiocyanates of the formula (I)r -- n.dbd.c.dbd.s (i)in which R is a straight or branched alkyl group with 1 to 18 carbon atoms, preferably methyl, and wherein the alkyl group can be substituted once or more by --OH, --OR.sup.1 or --SR.sup.1 and where R.sup.1 is an alkyl group of 1 to 6 carbon atoms or R is cycloalkyl with 3 to 8 carbon atoms, benzyl or phenyl in which the aromatic nucleus can be substituted once or more by a chlorine atom, a bromine atom, a hydroxyl group, or --R.sup.1, --OR.sup.1 or --SR.sup.1 or R is a pyridyl or thiazolyl group prepared by reacting (1) a dithiocarbamate of the general formula (II) ##STR1## where R is as defined above and Me is an alkali atom, one valence of an alkaline earth metal atom or the ammonium group whose hydrogen atoms can be substituted by R with (2) a cyanogen halide, preferably cyanogen chloride, in the presence of water. There is employed one mole of a dithiocarbamate of formula II as a 5 to 50 weight % aqueous solution in the presence of an inert organic solvent which is not miscible with water, and preferably in the presence of a base at a temperature from about -10.degree. C to about +50.degree. C, preferably between 0.degree. C and 25.degree. C. There is employed at least one mole of cyanogen chloride per mole of dithiocarbamate. The isothiocyanate produced is isolated from the organic phase.
摘要:
A heavy concentration of volatile substances and high degree of purity are achieved in a short time in a closed system by transferring the volatile substances from a vessel containing the gas phase into a condensation vessel by means of a capillary with a small inner diameter. Preferably there is a temperature drop from the vessel containing the gas phase to the condensation vessel.