DFT study on isomerization and decomposition of cuprous dialkyldithiophosphate and its reaction with alkylperoxy radical.
DFT study on isomerization and decomposition of cuprous dialkyldithiophosphate and its reaction with alkylperoxy radical.
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DOI：
10.1021/jp801571b
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发表时间：
2008-05
期刊：
影响因子：
--
通讯作者：
Yi Luo;S. Maeda;K. Ohno
中科院分区：
文献类型：
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作者：
Yi Luo;S. Maeda;K. Ohno
二烷基二硫代磷酸亚铜[（RO）2 PS2 Cu，CuDDP]作为抗氧剂已在工业上应用于润滑油中。在本文中，第一次，计算研究已经进行了CuDDP。采用标度超球搜索方法研究了CuDDP模型化合物（HO）2 PS2 Cu的异构化和分解途径及其与CH 3 OO * 自由基的反应.计算在B3 LYP水平上进行。结果表明，（HO）2 PS2 Cu的最稳定结构为赝C2 v对称结构，由P、Cu和两个S原子组成的四元环.键重排异构化导致的（H）O-桥结构是动力学上可行的。（HO）_2PS_2Cu的三个解离通道均需要较高的能量（>60 kcal/mol）。（HO）2 PS2 Cu与CH 3 OO * 的反应包括键重排异构化和CH 3 OO * 部分的分解。（HO）_2PS_2Cu辅助CH_3OO ~* 分解是通过O-O键断裂或C-O键解离进行的。计算表明，在低温下前者的分解方式优于后者，但在较高温度下，后者的分解方式更可取。这种吸热但可能的分解反应可能与CuDDP的抗氧化过程有关。
The cuprous dialkyldithiophosphate [(RO)2PS2Cu, CuDDP] as an antioxidant has been industrially used in lubricating oil. In this paper, for the first time, a computational study has been carried out for CuDDP. The scaled hypersphere search method has been used to explore the isomerization and decomposition pathways of (HO)2PS2Cu, a model compound of CuDDP, and its reaction with CH3OO* radical. The calculations were performed at the B3LYP level of theory. The results show that the most stable structure of (HO)2PS2Cu has pseudo-C2v symmetry and a four-membered ring constructed by P, Cu, and two S atoms. The bond-rearrangement isomerization leading to a (H)O-bridging structure is kinetically feasible. Three dissociation channels have been found for (HO)2PS2Cu, which require high energy (>60 kcal/mol) under the investigated condition. The reaction of (HO)2PS2Cu with CH3OO* includes bond-rearrangement isomerization and the decomposition of CH3OO* moiety. The (HO)2PS2Cu-assisted CH3OO* decomposition occurs via its O-O bond cleavage or the C-O bond dissociation. The former decomposition manner has been computed to be preferable over the latter at low temperature, but calculations suggested for the latter decomposition manner at higher temperature. Such a decomposition reaction, which is endothermic but possible, may be related to the antioxidation process of CuDDP.