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

• US 5,770,774 A
• Filed: 12/02/1996
• Issued: 06/23/1998
• Est. Priority Date: 04/25/1996
• Status: Expired due to Fees

• Current Assignee: Korea Kumho Petrochemical Co Limited (Korea Kumho Petrochemical)
• Original Assignee: Korea Kumho Petrochemical Co Limited (Korea Kumho Petrochemical)
• Inventors: Kim, Jin-Eok, Joo, Young J., Won, Jeong-Im, Hwang, Kum-Ui
• Primary Examiner(s): Geist, Gary
• Assistant Examiner(s): Vollano, Jean F.
• Application Number:
  US08/758,921
• Time in Patent Office: 568 Days
• Field of Search: 568/317, 568/312, 568/328
• US Class Current: 568/317
• CPC Class Codes: C07C 45/69 by addition to carbon-to-carbon double or triple bonds
• CPC Class Codes: C07C 46/02 by oxidation giving rise to quinoid structures
• CPC Class Codes: C07C 49/637 the condensed ring system containing ten carbon atoms
• CPC Class Codes: C07C 50/10 the quinoid structure being part of a condensed ring system containing two rings

Abstract

A method for preparing 2-methyl-1,4-naphthoquinone (vitamin K₃), 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.

Claims

1. A method for preparing 2-methyl-1,4-naphthoquinone through a 2+4! Diels-Alder reaction of 2-methyl-1,4-benzoquinone with 1,3-butadiene to obtain 2-methyl-4a,5,8,8a-tetrahydro-1,4-naphthoquinone and a dehydrogenation of the obtained 2-methyl-4a,5,8,8a-tetra-hydro-1,4-naphthoquinone in the presence of a dehydrogenating catalyst, the dehydrogenating catalyst selected from the group consisting of a Lewis acid and a Broensted acid, the method comprising the step of:

carrying out simultaneously the 2+4! Diels-Alder reaction and a dehydrogenation in a single pot by using dimethylsulfoxide as a dehydrogenating agent and as a solvent for the 2+4! Diels-Alder reaction.

2. The method in accordance with claim 1, wherein at least one Lewis acid is selected from the group consisting of SnCl₄.nH₂ O, FeCl₃.nH₂ O, AlCl₃ and BF₃ and said Broensted acid is p-toluenesulfonic acid.

3. The method in accordance with claim 1, wherein said dehydrogenation catalyst is used in an amount of 1 to 70% by weight relative to 2-methyl-1,4-benzoquinone.

4. The method in accordance with claim 1, wherein said 2+4! Diels-Alder reaction and said dehydrogenation are carried out at a temperature ranging from 100°

to 150°

C.

5. The method in accordance with claim 1, wherein said reaction solvent is a mixture of dimethylsulfoxide and an organic solvent.