Replacement of potassium hydride by sodium methoxide,replacement of hydrogen chloride by HCl-ethanol,and replacement of ether by toluene were in the improved procedure.

• 以甲醇钠代替氢化钾作为缩合剂；以盐酸乙醇代替氯化氢气体；以甲苯代替乙醚；对此工艺进行了改进。结果:得到较好的工艺条件；总收率达到47.；4%25。