From Zn(C6F5)2 to ZnEt2-based Lewis Pairs: Significantly Improved Catalytic Activity and Monomer Adaptability for the Ring-opening Polymerization of Lactones was written by Wang, Bin;Wei, Yuan;Li, Zong-Jun;Pan, Li;Li, Yue-Sheng. And the article was included in ChemCatChem in 2018.HPLC of Formula: 79-55-0 This article mentions the following:
In this contribution, the structure-reactivity relationships of ZnR2/DMAP (R=C6F5, C6H5 and C2H5) Lewis pairs in ring-opening polymerization (ROP) of lactones were investigated by crystallog. anal., d. functional theory (DFT) calculations and kinetic studies. With decrease of ZnR2 Lewis acidity, the interaction between ZnR2 and DMAP weakens and the dissociation of ZnR2路2DMAP Lewis adducts become easier, which facilitates the activation of cyclic ester monomers. Thus, the ZnEt2/DMAP Lewis pair, bearing weakest interaction between Lewis acid and Lewis base, exhibits high catalytic activity and broad monomer adaptability. ZnEt2路2DMAP can convert lactide (LA) rapidly into polylactide (PLA) even at room temperature Furthermore, a wide range of cyclic esters can also be polymerized using this dual catalyst, from small lactones such as 尾-butyrolactone (尾-BL), 未-valerolactone (未-VL) and 蔚-caprolactone (蔚-CL) to the strainless macrolactone. The optimal reaction pathway, key species and active species in the ZnEt2路2DMAP catalytic ROP of LA were figured out by DFT calculations The results clearly indicated that a DMAP-LA exchange was necessary for activation of monomer, and the single mol. initiation is preferred. Meanwhile, the cyclic active species is more stable than the linear analogs, in which DMAP and ZnEt2 bond with each polymer chain end resp. and ZnEt2 interact with DMAP. The DFT calculation gives an account for the formation of the cyclic polyester in the ROP of LA by ZnR2-based Lewis pairs. In the experiment, the researchers used many compounds, for example, 1,2,2,6,6-Pentamethylpiperidine (cas: 79-55-0HPLC of Formula: 79-55-0).
1,2,2,6,6-Pentamethylpiperidine (cas: 79-55-0) belongs to piperidine derivatives. The piperidine structural motif is present in numerous natural alkaloids. These include piperine, which gives black pepper its spicy taste. Some chemotherapeutic agents have piperidine moiety within their structure, foremost among them, vinblastine and raloxifene.HPLC of Formula: 79-55-0
Referemce:
Piperidine – Wikipedia,
Piperidine | C5H11N – PubChem