频哪醇

In Chapter Ⅱ, the pinacol-coupling reactions of carbonyl compounds promoted by dysprosium were described. The reaction of ketones and aldehydes promoted by Dy/n-BuBr were proceeded in anhydrous THF which gave pinacol in high yield.

第二章研究了金属镝促进下羰基化合物的还原偶联反应，醛、酮在无水THF中与Dy/n-BuBr反应，可高产率地得到频哪醇。

Methods for synthesizing of pinacol are reviewed,the difference of catalytic effects and stereoselectivity with various catalytic systems are introduced in this paper.Highlights are laid on the mechanism and stereoselectivity of new synthetic methods catalyzed by low valent Samarium, Titanium and Trimethyl chlorosilane, etc.

频哪醇合成新进展* The Recent Progress in the Synthesis of Pinacol 李有桂蒋昌盛尤田耙**(中国科学技术大学化学系合肥 230026)本文综述了合成频哪醇的方法，介绍了不同催化体系的催化效果和立体选择性的差异，着重介绍了低价钐、低价钛、三甲基氯硅烷等新的合成频哪醇反应的机理和立体选择性。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。