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The secondary alpha-deuterium, the secondary beta-deuterium, the chlorine leaving-group, the nucleophile secondary nitrogen, the nucleophile (12)C/(13)C carbon, and the (11)C/(14)C alpha-carbon kinetic isotope effects (KIEs) and activation parameters have been measured for the S(N)2 reaction between tetrabutylammonium cyanide and ethyl chloride in DMSO at 30 degrees C. Then, thirty-nine readily available different theoretical methods, both including and excluding solvent, were used to calculate the structure of the transition state, the activation energy, and the kinetic isotope effects for the reaction. A comparison of the experimental and theoretical results by using semiempirical, ab initio, and density functional theory methods has shown that the density functional methods are most successful in calculating the experimental isotope effects. With two exceptions, including solvent in the calculation does not improve the fit with the experimental KIEs. Finally, none of the transition states and force constants obtained from the theoretical methods was able to predict all six of the KIEs found by experiment. Moreover, none of the calculated transition structures, which are all early and loose, agree with the late (product-like) transition-state structure suggested by interpreting the experimental KIEs.

With the development of industry and improvement in living standards, carbon dioxide emissions have increased significantly year by year, causing serious environmental problems, such as global warming and climate change, which have been receiving much attention. [1] Effective capture and utilization of carbon dioxide is an important means to alleviate the increase in carbon dioxide content in the atmosphere. [2] The electrochemical reduction reaction of carbon dioxide (CO 2 RR) can not only effectively solve the problem of the environmental impact of excessive carbon dioxide emissions, but also convert unstable renewable resources to stable chemical energy for storage. [3] Therefore, the target of recent research is how to transfer carbon dioxide into valuable chemicals and fuels. [4] Among these high-value-added chemical substances, formic acid has one of the most wide ranges of application as a reactant material in the dye and leather industry. [5] Moreover, formic acid can also be treated as one of the centers of energy transportation and preservation, that is, for simple and effective conversion into H 2 or CO. [6] Compared with other possible chemical product conversion pathways, the reduction process of CO 2 to C1 products (CO and formic acid) is a classic double electron transfer reaction that occurs easily, and the electron utilization efficiency is very high. Therefore, it is considered to be an economically feasible, simple, and effective method. [7] Due to the thermodynamic stability of carbon dioxide molecules, the reduction process is difficult to complete spontaneously. The participation of the catalyst can shorten the time

Luminol electrochemiluminescence is dramatically increased by about five hundred times by taking full advantage of both electrochemical reduction and electrochemical oxidation using simple linear sweep voltammetry, leading to sensitive detection.

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