Xianfu Luo

The Separation of Catechol from Carbofuran Phenol by Extractive Distillation

Abstract In this study, extractive distillation has been applied to separate catechol (CAT) from carbofuran phenol(CFP) with high purity and yield. The relative volatility of CFP to CAT was measured, and the choice of separating agents was investigated. The experimental results indicated that CFP/CAT is an azeotropic system with an azeotropic point at 93.40°C/0.400 kPa and an azeotropic mixture containing 49.96% of CFP and 50.04% of CAT. Data from the determination of the relative volatility have shown that separating agents such as diglycol and 4-butylcatechol (4-TBC) are able to increase the relative volatility up to 1.90. In one shot process batch extractivedistillation of CFP mixture with 3% (by mass) diglycol as separating agent, the purity and yield of the obtained CFP was 99.0% and 95.0%, respectively, while the distillation without separating agent provided a purity and yield ofonly 98.0% and 90.0%, respectively. There was no residual separating agent found in the product.

Bis(2,2-dimethyl-2,3-dihydro-1-benzofuran-7-yl) carbonate.

The title compound, C21H22O5, crystallizes with three molecules in the asymmetric unit. In one molecule, two methyl groups are disordered over two positions with a site occupation factor of 0.72 (2) for the major occupancy site. The benzene rings make dihedral angles of 35.3 (6), 29.7 (6) and 40.6 (7)° in the three molecules.

2,2,7,7-Tetra­methyl-2,3,6,7-tetra­hydro­benzofuro[7,6-b]furan

The title compound, C14H18O2, was obtained as a by-product during the preparation of carbofuran phenol. The two dihydrofuran rings are in envelope conformations.

2-(2,2-Dimethyl-2,3-dihydro-1-benzofuran-7-yl­oxy)acetic acid monohydrate

In the title compound, C12H14O4·H2O, the dihydrobenzofuran ring adopts an envelope conformation with the substituted C atom 0.142 (1) Å out of the least-squares plane. In the crystal, the components are linked via intermolecular Owater—H⋯O and O—H⋯Owater hydrogen-bonding interactions, forming a three-dimensional network.