MY116956A - Process for the production of 2h-1-benzopyrans - Google Patents

Abstract

A PROCESS FOR THE PRODUCTION OF 2H-1-BENZOPYRANS WITH THE GENERAL FORMULA (FORMULA 1) WHERE R1 IS HYDROGEN, A (C1-C4) ALKYL GROUP, R2 IS HYDROGEN, A (C1-C6) ALKYL GROUP AND R3 IS HYDROGEN, A (C1-C4)ALKYL GROUP, A (C1-C4) HALOALKYL GROUP, A (C2-C4) ALKENYL GROUP, A (C1-C4) ALKOXYCARBONYL GROUP, A (C1-C4) ALKOXYMETHYL GROUP, A (C1-C4) ALKANOYL GROUP, A (C1-C4) ALKOXY GROUP, A (C1-C4) ALKYLSULPHONYL GROUP, HALOGEN, AMINO, ALKYLAMINO, DIALKYLAMINO, NITRIL, NITRO OR HYDROXY, IS CHARACTERISED IN THAT IN A FIRST STAGE AN ALIPHATIC ALDEHYDE WITH THE GENERAL FORMULA (FORMULA 2) WHERE R1 AND R2 HAVE THE ABOVE-MENTIONED MEANING, IS CONVERTED WITH AN ALIPHATIC ALCOHOL WITH THE FORMULA R4OH OR HOR4OH, WHERE R4 IS A (C1-C4) ALKYL GROUP OR A (C2-C4) ALKYLDIYL GROUP, IN THE PRESENCE OF A DEHYDRATING COMPOUND WITH THE FORMULA HC(OR5)3, WHERE R5 IS A (C1-C4) ALKYL GROUP, AND AN ALUMINIUM OXIDE/SILICIUM OXIDE CATALYST INTO A ALIPHATIC ACETAL WITH THE GENERAL FORMULA (FORMULA 3) WHERE R1 AND R2 HAVE THE ABOVE-MENTIONED MEANING AND R4 AS STATED ABOVE IS A (C1-C4) ALKYL GROUP OR THE TWO R4 TOGETHER ARE A CYCLICAL (C2-C4) ALKYLDIYL GROUP, AND THIS IS THEN CONDENSED IN A SECOND STAGE WITH A PHENOL WITH THE GENERAL FORMULA(FORMULA 4) WHERE R3 HAS THE ABOVE-MENTIONED MEANING, IN THE PRESENCE OF A BASE IN AN INERT ORGANIC SOLVENT, TO THE END PRODUCT WITH THE GENERAL FORMULA I.