Reaktion #415492

Reaktionsgleichung

4'-n-pentyl-4-acetylbiphenyl

hydrochloric acid

hypobromous acid

sodium bisulfite

bromine

→

4'-n-pentyl-4-biphenylcarboxylic acid

Ausbeute 84.0%

Lösungsmittel

sodium hydroxide

water

p-dioxane

p-dioxane

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigeprovided with a stirrer, a reflux condenser and a funnel
2. 2
   workup.ADDITIONfor dropwise adding),
3. 3
   workup.DISSOLUTIONdissolved
4. 4
   Temperaturcooled to 10°-15° C
5. 5
   workup.STIRRINGby stirring at 35°-40° C for 3 hours
6. 6
   workup.WAITto stand over one night
7. 7
   workup.STIRRINGstirring
8. 8
   Sonstigeseparating the resulting solid
9. 9
   Filtrationby filtration, water-
10. 10
    Waschenwashing
11. 11
    Sonstigedrying
12. 12
    Sonstigerecrystallizing from 6 l of acetic acid
13. 13
    Sonstigeto give

Vorschrift

883 Gram of 4'-n-pentyl-4-acetylbiphenyl was introduced into a 30 l stainless steel reactor (provided with a stirrer, a reflux condenser and a funnel for dropwise adding), added 3.75 l of p-dioxane and dissolved with stirring. On the other hand, 1.8 kg of bromine was dropwise added to and dissolved in a solution of 2 kg of sodium hydroxide dissolved in 7.5 l of water, cooled to 10°-15° C. The resulting hypobromous acid solution was maintained at about 10° C. This solution was dropwise added to the above-mentioned p-dioxane solution over 50 minutes, followed by stirring at 35°-40° C for 3 hours, allowing to stand over one night, adding 250 g of sodium bisulfite, stirring, neutralizing with 2.8 l of conc. hydrochloric acid, separating the resulting solid by filtration, water-washing, drying and recrystallizing from 6 l of acetic acid, to give 747 g of 4'-n-pentyl-4-biphenylcarboxylic acid of m.p. 177° C (smectic liquid crystal being formed) (Yield 84%).

Quelle