Reaktion #344842

Reaktionsgleichung

9-fluorenone

paraformaldehyde

sulfuric acid

sodium hydroxide

2-nitro-2'-hydroxy-5'-t-octylazobenzene

→

2-(2-hydroxy-5-t-octylphenyl)benzotriazole

Ausbeute 81.0%

Lösungsmittel

water

Methanol

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGthe reaction liquor is further stirred at the boiling point (73° C. ) for 6 hours
2. 2
   Sonstigethus the reduction reaction
3. 3
   Sonstigeto precipitate a crystal
4. 4
   SonstigeThe crystal thus obtained
5. 5
   Filtrationis filtered by suction
6. 6
   Sonstigeto separate the crystal
7. 7
   Waschenthe separated crystal is fully washed with water and further with methanol
8. 8
   SonstigeThe washed crystal is then dried

Vorschrift

Example 11 of U.S. Pat. No. 4,780,541 is duplicated. This is an example of the use of an aldehyde reducing agent and the aromatic ketone 9-fluorenone as a catalyst. Methanol (110 ml), water (20 ml), 97% sodium hydroxide (12.4 g), and 2-nitro-2'-hydroxy-5'-t-octylazobenzene (17.8 g) are mixed and stirred. After adding 9-fluorenone (2.4 g) to the resultant mixture at 65° to 70° C., 80% paraformaldehyde (6 g) is added to the mixture for 4 hours, and then the reaction liquor is further stirred at the boiling point (73° C. ) for 6 hours, thus the reduction reaction having completed. Thereafter, water (50 ml) is added to the reaction liquor, and the reaction liquor is neutralized to pH 8 with 62% sulfuric acid (16 g) to precipitate a crystal. The crystal thus obtained is filtered by suction to separate the crystal, and the separated crystal is fully washed with water and further with methanol. The washed crystal is then dried, thus producing 13.1 g of 2-(2-hydroxy-5-t-octylphenyl)benzotriazole having a melting point of 103° to 105° C. at the yield of 81.0%. One can see that the reaction takes over 10 hours to complete.

Quelle