光促进下N,N-二甲基甲酰胺作为一氧化碳源的烯烃氢酯化反应

 研究了光照下以N,N-二甲基甲酰胺(DMF)为一氧化碳源的烯烃氢酯化反应. 结果表明,在常温常压和光照射条件下DMF可以分解得到CO,新生成的CO在光促进下可以直接与CH3OH-DMF溶液中的底物1-辛烯在温和条件和非贵金属钴化合物(Co(OAc)2,CoCl2,Co(en)3Cl2和大环钴Co(14)4,11-二烯-N4]I2)催化下进行氢酯化反应,反应中DMF既是溶剂,又是原料. H13CON(CH3)2同位素示踪实验证实了这一结果. 在反应体系中通入二氧化碳可以大大提高反应的转化率、产率及选择性. 13CO2同位素示踪实验表明,CO2并未参与产物的形成,其作用是中和DMF分解产生的HN(CH3)2,从而有利于DMF的光促分解.

Dimethylformamide as Carbon Monoxide Source in Photoassisted Hydroesterification of Olefins

The hydroesterification of olefins is an essential reaction to synthesize valuable acid derivatives and carbon monoxide is the most commonly used carbon source for the formation of carbonyl groups. In this paper, it is found that N,N-dimethylformamide (DMF) can be decomposed under irradiation and conveniently used as a carbon monoxide source for the hydroesterification of 1-octene under ambient conditions with non-precious transition metal complex catalysts (such as cobalt complexes) in CH 3OH-DMF, which has been proved by isotope tracer experiment with H 13CON(CH 3) 2. A typical reaction procedure is as follows. A quartz test tube containing a solution of 100 mmol/L 1-octene and 6 mmol/L catalyst in 5 ml CH 3OH-DMF (CH 3OH to DMF volume ratio=2 6) was irradiated using a high-pressure mercury lamp of 400 W at room temperature. The products were characterized by GC and GC-MS. The 1-octene conversion and ester yield are 70% and 45%, respectively, catalyzed by Co(OAc) 2. Several other cobalt complexes such as CoCl 2, Co(en) 3Cl 2 and Co(14)4,11-diene- N 4]I 2 were also used to catalyze the reaction with the ester yields of 40%, 30% and 26%, respectively. The 1-octene conversion and ester yield are increased to 97% and 85%, respectively, in the presence of CO 2 at atmospheric pressure under the catalysis of Co(OAc) 2. And the ester yields are 83%, 55% and 49%, respectively, when using CoCl 2, Co(en) 3Cl 2 and Co(14)4,11-diene-N 4]I 2 as catalysts. The 13CO 2 isotope tracer experiment proved that CO 2 does not take part in the hydroesterification of 1-octene. It is reasonable to postulate that CO 2 neutralizes the HN(CH 3) 2 formed by decomposition of HCON(CH 3) 2, which is beneficial to the shift of chemical balance and may produce much CO. Adding acetic acid to the system can also promote the reaction. The efficiency of CO hydroesterification is much higher than that of CO 2 so that there is no hydroesterification of CO 2 in the presence of CO.