摘要:
A method has been disclosed of obtaining high purity, colourless monochloroacetic acid encompassing the chlorination of acetic acid with chlorine in the presence of a catalyst, followed by the recovery of the catalyst through vacuum distillation and purification of the obtained liquid raw product by its hydrodehalogenation by hydrogen in the presence of a palladium catalyst and then vacuum distillation.
摘要:
Provided is a method of preparing and recovering 2-methyl-5-iodobenzoic acid. The method utilizes o-methylbenzoic acid as raw material, iodinating via iodine/potassium persulfate in a mixed acid solvent to obtain a mixture of 2-methyl-5-iodobenzoic acid, 2-methyl-3-iodobenzoic acid, and 2-methyl-3, 5-diiodobenzoic acid; refining to obtain 2-methyl-5-iodobenzoic acid and recoverable mother liquor, the recoverable mother liquor being a mixture of 2-methyl-5-iodobenzoic acid, 2-methyl-3-iodobenzoic acid, and 2-methyl-3, 5-diiodobenzoic acid; conducting catalytic hydrogenation and deiodination to recover o-methylbenzoic acid and iodide ions; and oxidating the iodide ions to recover iodine. The whole process is recycled. The preparation and recovery method has cheap and easily available raw materials, and is easy of operation, has low requirements for equipment, and is suitable for large-scale industrial production.
摘要:
Described herein is a method for preparing methacrylic acid, comprising the following steps: Halogenating isobutyric acid to obtain 3-haloisobutyric acid, and dehalogenating the 3-haloisobutyric acid to obtain methacrylic acid.
摘要:
The invention relates to a method for the coupling production of acetic acid or propionic acid reaction products and a vinyl ester of formula R-C(O)O-CH = CH2 by a transvinylation reaction of a carboxylic acid of formula R-C(O)OH with a transvinylation reagent of formula R 1 -C(O)O-CH = CH 2 wherein R represents an aliphatic, cycloaliphatic or aromatic radical and R 1 is methyl or ethyl and the transvinylation reaction is continuously carried out without removing a reaction partner in the presence of a transition metal catalyst containing at least one transition metal selected from the group comprising ruthenium, osmium, rhodium, iridium, palladium and platinum, the obtained reaction mixture being separated from its components, the vinyl ester of formula R-C(O)O-CH = CH2 and the carboxylic acid of formula R 1 -C(O)-OH being separated and the thus obtained carboxylic acid R 1 -C(O)-OH being converted into a derivative of formula R 1 -C(O)-X, R 1 -CH 2 -OH or R 6 -C(O)-OH.
摘要:
The present invention provides a novel method for the preparation of 18 F-fluoride ( 18 F) for use in radiofluorination reactions. The method of the invention finds use especially in the preparation of 18 F-labelled positron emission tomography (PET) tracers. The method of the invention is particularly advantageous where bulk solutions are prepared and stored in prefilled vials rather than being freshly prepared on the day of synthesis. Also provided by the present invention is a radiofluorination reaction which comprises the method of the invention, as well as a cassette for use in carrying out the method of the invention and/or the radiofluorination method of the invention on an automated radiosynthesis apparatus.
摘要:
A process for producing 4-methyl-2,3,5,6-tetrafluorobenzyl alcohol comprising the following steps (A) to (D): Step (A): a step for fluorinating 2,3,5,6-tetrachloroterephthaloyl dichloride to obtain tetrafluoroterephthaloyl difluoride, Step (B): a step for reducing tetrafluoroterephthaloyl difluoride to obtain 2,3,5,6-tetrafluoro-1,4-benzenedimethanol, Step (C): a step for chlorinating the 2,3,5,6-tetrafluoro-1,4-benzenedimethanol to obtain 4-chloromethyl-2,3,5,6-tetrafluorobenzyl alcohol, Step (D): a step for hydrogenating the 4-chloromethyl-2,3,5,6-tetrafluorobenzyl alcohol.