中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
—— | 7-methoxy-6-methyl-3-oxo-1,3-dihydroisobenzofuran-4-carboxylic acid | —— | C11H10O5 | 222.197 |
—— | 4H-benzo[1,3]dioxin-5,6-dicarboxylic acid | 858789-94-3 | C10H8O6 | 224.17 |
—— | 7-hydroxy-6-methyl-3-oxo-phthalan-4-carboxylic acid | 856802-56-7 | C10H8O5 | 208.171 |
—— | 4-hydroxy-5-methyl-phthalide | 856807-83-5 | C9H8O3 | 164.161 |
The condensation of 3-hydroxy-4-methylbenzoic acid with aqueous formaldehyde and hydrochloric acid yields the lactone of 6-hydroxymethyl-1,3-benzodioxane-8-methyl-5-carboxylic acid. This dioxanylphthalide has also been produced in a similar type of condensation from 5-hydroxy-4-methylphthalide which can be obtained by demethylation with aluminum chloride of 5-methoxy-4-methylphthalide.Proof of the presence of the m-dioxane and phthalide rings in the condensation product has been obtained by opening these rings in succession. The action of alkaline permanganate opens the phthalide ring to yield a substituted phthalic acid. Acid hydrolysis then opens the m-dioxane ring with loss of formaldehyde and the formation of a new phthalide ring. Successive steps of decarboxylation, methylation, and oxidation of the new phthalide yield the known 3-methyl-4-methylphthalic acid.