4-(5-chloro-2-benzoxazolyl)Benzenamine synthesis

Yield:293737-78-7 74%

Reaction Conditions:

with phosphoric acid at 80 - 145;

Steps:

3.2

Step 2: add 480ml polyphosphoric acid to the 1000ml reactor,120ml phosphoric acid, heated to 80 ,Start stirring, then add 2-amino-4-chlorophenol 100.0g (molecular weight 143.57, 0.70mol)After stirring for half an hour, add p-aminobenzoic acid 105.1g (molecular weight 137.14, 0.77mol);heated to 145°C,After 1-5 hours of reaction, the temperature was lowered to 80°C,Add to 1200ml water to quench for 1-2 hours,The solid crude product was obtained by suction filtration with a suction filtration funnel, and 200 ml of water was added for rinsing. The solid crude product was dissolved in 3000 ml of ethyl acetate and passed through a silica gel column.After concentrating, obtain fine product 5-chloro-2-(4-aminophenyl) benzoxazole,HPLC=99.0%, 126.1 g (molecular weight 244.68, 0.70 mol) yield 74%.

References:

CN114436971,2022,A Location in patent:Paragraph 0071-0072; 0074