P-toluic acid

1. Nws yog npaj los ntawm catalytic oxidation ntawm p-xylene nrog cua.Thaum siv cov txheej txheem atmospheric siab, xylene thiab cobalt naphthenate tuaj yeem muab ntxiv rau hauv cov tshuaj tiv thaiv lub lauj kaub, thiab cua yog qhia thaum cua sov rau 90 ℃.Cov tshuaj tiv thaiv kub yog tswj ntawm 110-115 ℃ li ntawm 24 teev, thiab li 5% ntawm p-xylene hloov mus rau p-methylbenzoic acid.Txias rau chav sov, lim, ntxuav lub ncuav mog qab zib nrog p-xylene, thiab qhuav kom tau p-methylbenzoic acid.P-xylene rov ua dua.Cov txiaj ntsig yog 30-40%.Thaum siv txoj kev oxidation siab, cov tshuaj tiv thaiv kub yog 125 ℃, lub siab yog 0.25MPa, cov pa roj ntws yog 250L hauv 1H, thiab lub sijhawm tshuaj tiv thaiv yog 6h.Tom qab ntawd, cov xylene uas tsis muaj kev cuam tshuam yog distilled los ntawm chav, cov khoom siv tshuaj oxygen yog acidified nrog concentrated hydrochloric acid rau pH 2, stirred thiab txias, thiab lim.Lub ncuav mog qab zib lim tau soaked hauv p-xylene, ces lim thiab qhuav kom tau p-methylbenzoic acid.Cov ntsiab lus ntawm p-methylbenzoic acid yog ntau tshaj 96%.Kev hloov pauv ib-txoj kev ntawm p-xylene yog 40%, thiab tawm los yog 60-70%.

2.Nws tau npaj los ntawm oxidation ntawm p-isopropyltoluene nrog nitric acid.20% nitric acid thiab p-isopropyltoluene tau tov, nplawm thiab rhuab mus rau 80-90 ℃ rau 4h, ces rhuab mus rau 90-95 ℃ rau 6h.Txias, pom, recrystallization ntawm lim ncuav mog qab zib nrog toluene muab p-methylbenzoic acid nyob rau hauv 50-53% tawm los.Tsis tas li ntawd, p-xylene tau oxidized los ntawm concentrated nitric acid rau 30 h, thiab tawm los yog 58%.