3 results about "Alkaline hydrolysis" patented technology

The invention relates to the field of dyeing and finishing and discloses a method for dyeing a carboxymethyl chitosan silicon-modified cotton fabric with natural dyes. The method adopts a chitin alkaline hydrolysis approach for oxidoreduction to obtain chitosan after drying; glycidyl trimethoxy siloxane is added into a carboxymethyl chitosan solution to prepare a carboxymethyl chitosan silicon-hybrid system solution; a cotton fabric is soaked in the solution in a constant-temperature vibration dyeing machine, washed with water and then dried for later use; absolute ethyl alcohol is adopted forextracting a radix lithospermi dye mother liquor, and the pretreated cotton fabric is put into the radix lithospermi dye mother liquor for dyeing through an ethyl alcohol dissolution assistance approach; the temperature is lowered after dyeing is finished, and washing and drying are performed. When the method is used for dyeing the cotton fabric with the natural dyes, the advantages of simple operation, high dyeing rate, energy conservation and environmental protection are achieved.

The invention provides a sucralose-6-ester purification method, which comprises: adding an oxidizing agent to a mother solution to be purified, carrying out an oxidation reaction under a first preset condition, adding an alkaline hydrolysis agent, and carrying out an alkaline hydrolysis reaction under a second preset condition to convert target impurities into sucralose-6-ester so as to obtain an oxidation alkaline hydrolysis reaction solution, adjusting the pH value of the oxidation alkaline hydrolysis reaction liquid to be neutral, keeping for a period of time, then heating and filtering to remove insoluble impurities, and then separating liquid to obtain a first water phase and a first organic phase; extracting the first water phase by adopting an extracting agent, and combining a second organic phase obtained by extraction with the first organic phase to obtain mother liquor to be crystallized; and a crystallization step: concentrating the mother liquor to be crystallized, and crystallizing under a third preset condition to obtain a sucralose-6-ester crude product and a first filtrate. According to the method, the impurity content is effectively reduced, and meanwhile, the yield of a target product is greatly improved.

The invention discloses a preparation method of tetraalkylthiuram monosulfide, which comprises the following steps: preparing a mixed solution from water, monohydric alcohol and carbon disulfide, sequentially dropwise adding secondary amine, hydrogen peroxide, a sodium cyanide aqueous solution and a triphenylphosphine alcohol solution into the mixed solution for reaction, and finally carrying out solid-liquid separation, drying and crushing on reactants to obtain the tetraalkylthiuram monosulfide. According to the method, a mixed solvent is adopted as a reaction medium, dimethylamine, carbon disulfide and hydrogen peroxide are adopted as raw materials, and the tetraalkylthiuram monosulfide is prepared in a mode that two desulfurization reagents are superposed. The reaction is carried out in a uniformly dispersed neutral system, alkaline hydrolysis of tetraalkylthiuram monosulfide is effectively controlled, the product yield is increased from about 85% to more than 98.5%, the purity is greater than or equal to 99.0%, and by-products sodium thiocyanate and triphenylphosphine sulfur can be used as chemical raw materials for resource utilization; and the method can be carried out on conventional equipment, adopts low-temperature reaction, and is high in safety.