A4-Tetrahydrophthalic anhydride

Dimethyl ew>-A4-tetrahydrophthalate can be prepared by a similar procedure. cis-A4-Tetrahydrophthalic anhydride (228 g., 1.5 moles) is heated under reflux with 364 ml. (9 moles) of commercial anhydrous methanol and 2.5 g. of />-toluenesulfonic acid monohydrate for 12-16 hours. At this time 270 ml. of toluene is added and the mixture is distilled. When the distillation temperature drops from 68-70° to 45°, after about 4-6 hours, 364 ml. of absolute methanol is added and the mixture again is heated under reflux for 12 16 hours. An additional 270 ml. of toluene is added, and distillation is continued for 4-6 hours. The residual liquid is purified by a procedure similar to the one described for (lie ethyl ester. The yield of dimethyl cw-A4-tetrahydrophthal-alc, boiling at 120 122°/5 mm., 1.4700, is 239 g. (80%). 

Whereas cis-A4-tetrahydrophthalic anhydride and several of its derivatives are readily available in high purity from a... 

Diethyl cis-hexahydrophthalate has been prepared from cis-hexahydrophthalic acid, absolute ethanol, and sulfuric acid,4-5 and from cis-hexahydrophthalic anhydride, absolute ethanol, and sulfuric acid.6 Diethyl cw-A4-tetrahydrophthalatc has been prepared from cfs-A4-tetrahydrophthaIic acid or its anhydride, ethanol, and sulfuric acid.7 Dimethyl cw-A4-tetrahydrophthalate and dimethyl efs-hexahydrophthalate have been synthesized by the procedures of this preparation.8... 

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