Kyowa Gas Chemical Industry Company, Ltd.

Mitsui Toatsu Chemicals, Incorporated

Kuraray Co., Ltd.

Hirozo Segawa

Morimasa Kuragano

Katsuji Yoguchi

Akira Nakamura

Takeshi Isobe

Minoru Koshibe

Toshiei Ataka

Tetsuo Takematsu

Yoshihiro Sezaki

Kozo Iwasaki

Takamaro Miura

Michio Chatani

Isao Fukada

Rensuke Ikarashi

Nobutaka Ueda

Yoshio Koyama

Shin-ichi Tadokoro

Norio Ishikawa

Matsuo Ono

Hideo Shirakawa

Shizuo Noguchi

A process is provided for the purification of methacrylic acid. The process can easily remove dibasic acids and aldehydes containing in trace amounts as impurities. According to the process, crude methacrylic acid obtained as an aqueous solution by vapor-phase catalytic oxidation of isobutylene, tertiary butanol, methacrolein or isobutyl aldehyde is treated with at least one compound selected from the group consisting of m-aminophenol, m-phenylenediamine, 2,4-diaminotoluene and 2,4-diamino-diphenylamine, followed by distillation, optionally, in the presence of a p-phenylene diamine.

Purification process of methacrylic acid

Provided is a process for producing chlorosulfonyl isocyanate by reacting sulfur trioxide with cyanogen chloride, which comprises feeding sulfur trioxide and cyanogen chloride simultaneously to the reaction zone and maintaining the temperature of the reacting zone at 10.degree. to 50.degree. C. This is a commercially very simple process and can produce chlorosulfonyl isocyanate with high purity in high yield.

Process for producing chlorosulfonyl isocyanate

A purification process for methyl methacrylate (MMA) and a recovery process for methanol are disclosed. A mixture, which contains water, methanol and methyl methacrylate (MMA) as principal components along with at least one of methyl acrylate, methyl propionate and methacrylic acid, is azeotropically distilled together with hexane to obtain MMA in a form substantially free of water, methanol methyl acrylate, methyl propionate and hexane and a low boiling-point fraction. The low boiling-point fraction is cooled and separated into a water phase and an oil phase. Methanol can be recovered from the water phase by adding an alkaline substance to it and then distilling the resultant mixture. A preparation process of MMA is also disclosed. MMA can be prepared by esterifying methacrylic acid or methacrylamide with methanol and then applying the above purification process.

Purification and preparation processes for methyl methacrylate

In order to recover methacrolein and/or methacrylic acid by quenching a reaction product gas obtained by catalytic oxidation of isobutylene or the like, the reaction product gas is charged into a quench column through a double-wall pipe and is then brought into contact with a condensate as a cooling medium. Deposition of terephthalic acid and the like inside the column is prevented by controlling the temperature of a bottom in the quench column and that of an overhead gas of a quench column unit. An aromatic carboxylic acid, aromatic aldehyde, metal powder is added to an aqueous solution of methacrylic acid, which contains terephthalic acid and the like, so that the terephthalic acid and the like are caused to precipitate for their removal.

Quenching process of reaction product gas containing methacrylic acid

This invention provides a method for the prevention of oxidation of resulting methacrolein immediately after its discharge from a reaction tube upon production of the methacrolein by vapor-phase oxidation of isobutylene, tertiary butanol or methallyl alcohol with a molecular-oxygen-containing gas in the presence of a catalyst. An inert gas and/or recirculated reaction gas or a mixed gas of an inert gas and/or recirculated reaction gas and air is fed and mixed with a reaction product gas immediately after an outlet of the reaction tube.

Method for the prevention of post oxidation of methacrolein

Novel 2,3-dicyanopyrazine derivatives of the formula ##STR1## wherein A represents a hydrogen atom, a lower alkyl group, an unsubstituted or substituted phenyl group, a benzyl group, or a group of the formula --ZR.sub.1 in which Z represents an oxygen or sulfur atom and R.sub.1 represents an unsubstituted or substituted lower alkyl group, a lower alkenyl group, a lower alkynyl group, an unsubstituted or substituted phenyl group, or an unsubstituted or substituted benzyl group; and B represents a halogen atom, an alkyl group containing at least 3 carbon atoms, a phenyl group having a substituent at the ortho- and/or meta-position of the benzene ring, a group of the formula ZR.sub.1 in which Z and R.sub.1 are as defined, or a group of the formula ##STR2## in which R.sub.2 and R.sub.3, independently from each other, represent a hydrogen atom, an unsubstituted or substituted lower alkyl group, a lower alkenyl group, a cycloalkyl group, an unsubstituted or substituted phenyl group, or an unsubstituted or substituted benzyl group, with the proviso that R.sub.2 and R.sub.3 do not represent a hydrogen atom at the same time, and R.sub.2 and R.sub.3 together may form a 3- to 7-membered heterocyclic ring together with the nitrogen atom to which they are bonded, said heterocyclic ring optionally containing an additional hetero atom; and processes for production thereof. These compounds have high herbicidal activity, and are useful as active ingredients of herbicides.

2,3-Dicyano 6 phenyl pyrazine herbicides

A neutron shielding polymer composition comprising a polymerization product of a base monomer ingredient containing as an essential ingredient at least one monomer selected from the group consisting of alkyl methacrylates containing 1-4 carbon atoms in the alkyl group and styrene in admixture with a saturated boric acid ester which contains as an essential constituent component a polyol containing 3-16 carbon atoms and in which a molar ratio A of said polyol to boron atoms in said boric acid ester formed from said polyol being in the range of 0.6&lt;A&lt;4, the boron content B (wt. %) in the total monomer mixture being in the range of 1.ltoreq.B&lt;6.

Neutron shielding polymer composition and a process for producing the

Novel 2,3-dicyanopyrazine derivatives of the formula ##STR1## wherein A represents a hydrogen atom, a lower alkyl group, an unsubstituted or substituted phenyl group, a benzyl group, or a group of the formula -ZR.sub.1 in which Z represents an oxygen or sulfur atom and R.sub.1 represents an unsubstituted or substituted lower alkyl group, a lower alkenyl group, a lower alkynyl group, an unsubstituted or substituted phenyl group, or an unsubstituted or substituted benzyl group; and B represents a halogen atom, an alkyl group containing at least 3 carbon atoms, a phenyl group having a substituent at the ortho- and/or meta-position of the benzene ring, a group of the formula ZR.sub.1 in which Z and R.sub.1 are as defined, or a group of the formula ##STR2## in which R.sub.2 and R.sub.3, independently from each other, represent a hydrogen atom, an unsubstituted or substituted lower alkyl group, a lower alkenyl group, a cycloalkyl group, an unsubstituted or substituted phenyl group, or an unsubstituted or substituted benzyl group, with the proviso that R.sub.2 and R.sub.3 do not represent a hydrogen atom at the same time, and R.sub.2 and R.sub.3 together may form a 3- to 7-membered heterocyclic ring together with the nitrogen atom to which they are bonded, said heterocyclic ring optionally containing an additional hetero atom; and processes for production thereof. These compounds have high herbicidal activity, and are useful as active ingredients of herbicides.

2,3-Dicyanopyrazines

Growing community of inventors

Niigata, Japan

Hirozo Segawa