- Preparation method of 3-acetylthio-2-methylpropionic acid
-
The invention discloses a preparation method of 3-acetylthio-2-methyl propionic acid. The preparation method comprises the following steps: carrying out a reaction on a compound (methacrylic acid) represented by a formula I and hydrogen halide to obtain a compound represented by a formula II, carrying out a reaction on the compound represented by the formula II and sodium hydrosulfide or sodium sulfide to obtain a compound represented by a formula III, and performing an acetylation reaction to obtain a compound represented by a formula IV (3-acetylthio-2-methylpropionic acid). The process forsynthesizing the 3-acetylthio-2-methyl propionic acid has the advantages of being low in cost, easy and convenient to operate, good in yield, environmentally friendly and suitable for industrial production.
- -
-
Paragraph 0037-0040
(2020/05/02)
-
- Preparation method for methyl methacrylate
-
The invention relates to a preparation method for methyl methacrylate. The preparation method comprises the following steps: introducing oxygen into isobutyraldehyde at a temperature of 50 to 60 DEG Cand a pressure of 0.1 to 0.3 MPa in the presence of a solid oxidation catalyst for oxidization of the isobutyraldehyde, carrying out a reaction at an oxygen space velocity of 1000 to 1200 hours for 10 to 36 hours, and separating the solid oxidation catalyst so as to obtain an isobutyric acid solution; adding a halogen element and acetic anhydride into the isobutyric acid solution, and carrying out a reaction at a normal pressure and a temperature of 80 to 100 DEG C for 1 to 5 hours so as to obtain a halogenated isobutyric acid solution; adding sodium hydroxide and first methanol into thehalogenated isobutyric acid solution, carrying out a reaction at a normal pressure and a temperature of 50 to 80 DEG C for 5 to 15 hours, and carrying out filtering to remove impurities so as to obtain a methacrylic acid solution; and adding second methanol, an ionic liquid catalyst and cyclohexane into the methacrylic acid solution, carrying out a reaction at 70 to 90 DEG C for 2 to 12 hours, andcarrying out filtering and separation so as to obtain the methyl methacrylate. The preparation method provided by the invention has simple preparation process and high yield.
- -
-
Paragraph 0036-0049
(2019/11/12)
-
- HYDROCHLORINATION OF ELECTRON-DEFICIENT ALKENES
-
The present invention pertains to a method for the hydrochlorination of electron deficient alkenes, particularly alkenes having the functional groups COOH, CONH2, and CN. Specific alkenes discussed include acrylic acid, crotonic acid, methacrylic acid, acrylonitrile, acrylamide, and methacrylonitrile. The alkene is combined with a primary or secondary alcohol (e.g., isopropanol) and an acid chloride (e.g., acetyl chloride) under conditions suitable to chlorinate the alkene. Products formed by the invention include 3-chorosubstituted carbonyl compounds such as 3-chlorpropionic acid (3-CPA), 3-chloropropionamide (3-CPAD), and 3-chloropropionitrile among other products.
- -
-
Page/Page column 5
(2012/07/31)
-
- Development of the conditions of synthesis of p-chlorophenyl methacrylate of the desired purity grade
-
The process of synthesis of p-chlorophenyl methacrylate by the reaction of p-chlorophenol with methacryloyl chloride was developed, identification and quantitative determination of admixtures in the targeted compound was carried out. The optimal conditions of the synthesis for obtaining the high quality monomer were developed.
- Kobyakova,Kuz'Mina,Beshenova,Beloded
-
experimental part
p. 123 - 127
(2009/09/06)
-
- Optically active units for the synthesis of the side chain of (R,R,R)-α-tocopherol and their preparation
-
(2R,6R)-1-Chloro-2,6,10-trimethyl-undecane I, (R)-(+)-β-chloro-isobutyric acid II, (S)-(+)-1-bromo-3-chloro-2-methylpropane IV and (2R)-(+)-1-chloro-2,6-dimethyl-heptane V are novel optically active units for the synthesis of the side chain of (R,R,R)-α-tocopherol. In the process according to the invention, the optically active C14 -chloride I is obtained in 6 simple reaction steps starting from II, via the novel intermediates IV and V, in accordance with the following equation: STR1
- -
-
-
- An improved synthesis of captopril
-
An improved synthesis of captopril using methacrylic acid as the starting material is described. Treatment of methacrylic acid (I) with a hydrogen halide gave the 3-halogeno-2-methylpropanoic acids II and III, which were treated with thionyl chloride to yield the corresponding 3-halogeno-2-methylpropanoyl chlorides IV and V. Treatment of IV or V with L-proline yielded the N-(R,S-3-halogeno-2-methylpropanoyl)-L-prolines VI and VII, which were separated into optically pure R- and S-diastereoisomers using dicyclohexylamine. Treatment of halides of VI or VII with methanolic ammonium hydrosulfide gave captopril in 28% yield.
- Nam,Lee,Ryu
-
p. 1843 - 1844
(2007/10/02)
-
- Process for preparation of an optically active β-mercaptoalkanoic acid
-
A process is disclosed wherein an optically active β-mercaptoalkanoic acid represented by formula (I): STR1 wherein R1 is lower alkyl having from 1 to 4 carbon atoms, is prepared by (1) reacting an optically active β-hydroxyalkanoic acid represented by formula (II): STR2 wherein R1 is the same as defined above, with a halogenating reagent to prepare an optically active β-haloalkanoyl halide represented by formula (III): STR3 wherein X is halogen and R1 is the same as defined above; (2) reacting the β-haloalkanoyl halide with water or an aqueous alkaline solution to prepare an optically active β-haloalkanoic acid represented by formula (IV): STR4 wherein X and R1 are each the same as defined above, or a salt thereof, respectively; and (3) reacting the β-haloalkanoic acid or the salt thereof with a reagent capable of converting the halogen into the thiol group, the configuration of the compound (II), (III), and (IV) being retained throughout the process to prepare the compound represented by formula (I). The product of the present invention is useful as an intermediate for preparation of an antihypertensive agent such as N-(3-mercapto-2-D-methylpropanoyl)-L-proline.
- -
-
-