Korea Kumho Petrochemical Co., Ltd.

Jin-Eok Kim

Jeong-Im Won

Young J Joo

Kum-Ui Hwang

Sang Ho Park

Han Jin Kwag

Seoung-IL Kim

Kil-sun Lee

Seung-il Kim

Jung-hee Jang

Han-Jin Kwag

Young-J Joo

Hyung-Jae Lee

Jong-cheon Park

Provided is a method for preparing 4,4'-dinitrodiphenylamine (4,4&#x2032;-DNDPA) in high yield via the NASH reaction using a mixture of a bis-quaternary ammonium base and a base catalyst for the reaction of urea with nitrobenzene, and a method of preparing 4,4&#x2032;-bis(alkylamino)diphenylamine (4,4&#x2032;BAADA) in high yield and purity by hydrogenating the resulting 4,4&#x2032;-DNDPA with a ketone in the presence of hydrogen and hydrogenation catalyst. The catalyst complex used in the present invention allows easy recovery, provides superior alkaline stability and is capable of reducing production cost.

Method for preparation of 4,4'-dinitrodiphenylamine and 4,4&#x2032;-bis(alkylamino)diphenylamine with the base catalyst complex

Provided is a method of preparing 4,4'-dinitrodiphenylamine (4,4&#x2032;-DNDPA) in high yield by reacting 4-nitroaniline with excess nitrobenzene via the NASH reaction, and a method of preparing 4,4&#x2032;-bis(alkylamino)diphenylamine (4,4&#x2032;BAADA) in high yield and purity by hydrogenating the resulting 4,4&#x2032;-DNDPA with a ketone compound in the presence of hydrogen and hydrogenation catalyst. The disclosed process is simple, allows selective preparation of 4,4&#x2032;-DNDPA without byproducts, and thus allows preparation of 4,4&#x2032;-BAADA in high yield without a complicated purification procedure.

Method for preparation of 4,4'-dinitrodiphenylamine and 4,4&#x2032;-bis(alkylamino)diphenylamine by using 4-nitroaniline

The present invention relates to a method of preparing N-substituted maleimide in high purity and high yield, wherein, unlike a conventional method of preparing N-substituted maleimide after preparing N-substituted maleamic acid, an organic solvent, an acid catalyst, a dehydration co-catalyst and a stabilizer are added into a reactor without separately preparing N-substituted maleamic acid, and then a primary amine is added into the reactor to form an amine salt, maleic anhydride is added into the reactor, and the resulting mixture is subjected to a dehydration-cyclization reaction, wherein water produced during the reaction is azeotropically distilled with the organic solvent so as to effectively suppress formation of a maleimide polymer. Particularly, the invention simplifies the process, has high yield, minimizes side reactions, eliminates the introduction of expensive raw materials and the complicated treatment of the reaction solution and significantly shortens the time over which the raw materials and maleic anhydride are added.

Method for preparing N-substituted maleimides

The present invention relates to a process for preparing thiomethylphenol derivatives, and particularly to a simple process of preparing thiophenol derivatives by performing a reaction of a phenol derivative, a mercaptan derivative and paraformaldehyde in a solvent in the presence of a given amount of heterocyclic amine base and acids, thereby capable of maintaining a mild reaction condition and providing thiomethylphenol derivatives with an improved discoloration by purification using acids.

Method for preparing thiomethylphenols

4-aminodiphenylamine is prepared by reacting carbanilide and nitrobenzene in an adequate solvent, which may be nitrobenzene, in the presence of an appropriate organic base, which may be tetramethylammonium hydroxide, alone or in mixture with an inorganic base and subsequently reducing the reaction product in the presence of an appropriate catalyst and hydrogen gas. The subsequent reduction may be carried out on the reaction mixture before the reaction mixture is subjected to separation.

Method for preparing 4-aminodiphenylamine

Disclosed is a method for preparing a 4-nitroso-substituted aromatic amine that includes contacting an amide compound with a nitroaromatic compound in the presence of a base and a solvent to directly prepare 4-nitroso-substituted aromatic amine as a main product and 4-nitro-substituted aromatic amine as a by-product without producing 4-nitroso- or 4-nitro-substituted amide as an intermediate.

Method for preparing 4-nitroso-substituted aromatic amine

A method for preparing 4-nitrosoaniline, including reacting urea and nitrobenzene in a polar organic solvent in the presence of a base at a temperature of room temperature to 150&deg; C. The method uses a relatively cheap urea and nitrobenzene as the raw materials, and also a relatively cheap base, thereby decreasing the manufacturing cost. Urea used as an amine donor is excellent in a reactivity to nitrobenzene, and a reaction intermediate is unstable as compared with 4-(4-nitrophenyl)benzamide to easily decompose into 4-nitroaniline and 4-nitrosoaniline. This allows a reaction time and a process time to be shortened. Moreover, the method is advantageous in that waste hazardous to the environment is not produced as a byproduct.

Manufacturing method for 4-nitrosoaniline from urea and nitrobenzene

A method for preparing 4,4'-dinitrodiphenylamine, including reacting urea and nitrobenzene in a polar organic solvent in the presence of a base at a temperature of room temperature to 100.degree. C. The method employs a relatively cheap urea and nitrobenzene as the raw materials, and also employs a relatively cheap base, thereby decreasing the manufacturing costs. Moreover, the method does not produce by-products, thus eliminating a need for a post-treating process. Additionally, the method is advantageous in that the production of 4,4'-dinitrodiphenylamine can be achieved in high yield and selectivity even under non-intensive reaction conditions by appropriately controlling the amounts of urea and nitrobenzene.

Preparation of 4,4'-dinitrodiphenylamine from urea and nitrobenzene

A method for preparing 2-methyl-1,4-naphthoquinone (vitamin K.sub.3), in which 2-methyl-1,4-benzoquinone and 1,3-butadienes are subjected to a �2+4! Diels-Alder reaction and subsequently to oxidative dehydrogenation, using dimethylsulfoxide as both a dehydrogenating agent and a solvent in the presence of at least one Lewis acid or a Broensted acid, in a single pot, shows high selectivity and yield.

Method for preparing 2-methyl-1,4-naphthoquinone (vitamin K.sub.3)

A method for preparing anthraquinones, by which 1,4-benzoquinone or 1,4-naphthoquinone and 1,3-butadienes are subjected to a �2+4! Diels-Alder reaction and subsequently to oxidative dehydrogenation by using dimethylsulfoxide as a dehydrogenating agent in a single pot in the presence of a Lewis acid or Broensted acid shows high selectivity and yield.

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Daejeon, South Korea

Jin-Eok Kim