Reaktion #344831

Reaktionsgleichung

2-nitro-2'-hydroxy-3', 5'-di-t-amylazobenzene

sodium hydroxide

sulfuric acid

9-fluorenone

glucose

→

2-(2'-hydroxy-3', 5'-di-t-amylphenyl)benzotriazole

Ausbeute 85.0%

Lösungsmittel

water

methanol

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigethe reduction reaction
2. 2
   Sonstigeto precipitate a crystal
3. 3
   SonstigeThe crystal thus obtained
4. 4
   Sonstigeis separated by filtration
5. 5
   Waschenthe separated crystal is fully washed with water and further with methanol
6. 6
   SonstigeThe washed crystal is then dried

Vorschrift

Example 1 from EP 0,257,151 is duplicated. 2-nitro-2'-hydroxy-3', 5'-di-t-amylazobenzene (12.8 g) is added to a mixture of methanol (41 g), water (10 g) and 97% sodium hydroxide (11 g), and the resultant mixture is stirred at 65° C. for 30 minutes. Thereafter, 9-fluorenone (2.0 g) and then glucose (12 g) are added to the mixture at 60° to 65° C. over 4 hours. The resultant mixture is further stirred for 4 hours at the boiling point (70° C.), thus completing the reduction reaction. Thereafter, water (50 ml) is added to the reaction liquor, and the reaction liquor is neutralized with 62% sulfuric acid (13 g). The liquor thus neutralized is cooled to 20° C. to precipitate a crystal. The crystal thus obtained is separated by filtration, and the separated crystal is fully washed with water and further with methanol. The washed crystal is then dried, thus producing 9.9 g of 2-(2'-hydroxy-3', 5'-di-t-amylphenyl)benzotriazole having a melting point of 77° to 79° C. at the yield of 85.0%. One can see that the reduction reaction with the aromatic ketone 9-fluorenone takes over 81/2 hours to complete and requires three times as much catalyst.

Quelle