Study On Synthesis Of Resorcinol Derivatives

2,6-dihydroxyacetophenone and 2,4-dihydroxyacetophenone are both important intermediates,especially in medication.2,4-dihydroxyacetophenone(Ⅱ)was synthesized from resorcinol(Ⅰ)and acetic acid;2,6-dihydroxyacetophenone was synthesized from resorcinol by several steps.First synthesized of 7-hydroxy-4-methyl coumarin(Ⅳ)fromⅠand ethyl acetoacetate(Ⅲ),then followed by acetylation,the 4-methyl-7-acetoxy coumarin(Ⅴ)was synthesized,through Fries rearrangement,the 4-methyl-7-hydroxy -8-acetyl coumarin(Ⅵ)was synthesized.In the present of NaOH,2,6-dihyroxyacetophenone(Ⅶ)was syethesized..Through analyzing the factors of the reaction,found the optimum conditions.The structure of these compounds were identified by means of IR and NMR.The optimum conditions of the reaction are described as follows.(1)when the molar ratio ofⅠto acetic acid is 1:4.5,the use level of zinc chloride which is the catalyst in the reaction is 15g,the reaction temperature is 140℃and the rection time is 5h,the yield ofⅡis 91.58%.(2)when the molar ratio ofⅠtoⅢis 1:1.1 and the reaction time is 20h,the yield ofⅣis 90.63%.(3)when the molar ratio ofⅣto acetic anhydride to acetic acid is 1:2.5:5 and the reaction time is 2h,the yield ofⅤis 90.46%.(4)when the use level of Aluminium trichloride which is used as catalyst is 22.7g,the use level of nitrobenzene which is used as solvent is 10mL,the reaction temperature is 140℃and the reaction time is 2h,the yield ofⅥis 68.5%; when the use level of phosphotungstic acid which is used as catalyst is 5g,the use level of nitrobenzene which is used as solvent is 10mL,the reaction temperature is 160℃and the reaction time is 2h,the yield ofⅥis 65.6%(5)when the the molar ratio ofⅥto sodium hydroxide is 1:4 and the reaction time is 4h,the yield ofⅦis 87.24%.As describe above,when using nitrobenzene as solvent,the fluidity of the system is increased and the reaction can go on better.In the Fries rearrangement reaction,using heteropoly acid (phosphotungstic acid)instead of Lewis acid(Aluminium trichloride)which is used as catalyst, hydrogen chloride which is the acidic gas can be avoided in the reaction.