INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2023
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IF 4.2
Dongying Yan,Ruilin Feng,Yanlong Qi,Chenxi Bai
Selective synthesis of 1,3-pentadiene without 1,4-pentadiene formation is challenging as well as rewarding because of the widespread use of 1,3-pentadiene in adhesive, paint, and curing agent production. Herein, modified K–Ce/ZrSi catalysts with acid–base sites were synthesized for the production of 1,3-pentadiene from 1,4-pentanediol. The overall 1,3-pentadiene yield was 74.7%, while the 1,4-pentadiene yield was 1.3%. On the catalyst, two parallel routes (direct dehydration and dehydra-decyclization) for the conversion of 1,4-pentanediol to 1,3-pentadiene were disclosed. The 4-position hydroxyl group was first activated and then eliminated on the acid sites. It was considered that the acid–base sites of catalysts exhibited a synergistic effect for the selective dehydration of 1,4-pentanediol to 1,3-pentadiene, where the medium strength Lewis acid sites and weak base sites were responsible for the elimination of the hydroxyl group and the corresponding β1-H, thereby inhibiting the formation of 1,4-pentadiene. Furthermore, a plausible reaction network was proposed.
研究领域:
催化化学
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可再生化学品
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高影响因子
EUROPEAN POLYMER JOURNAL
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2023
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IF 6
Kun Liu,Qiaoqiao Xiong,Zhuowei Gu,Feng Zhang,Yawen Fu,Fengli Xie,Wenjun Yi,An Li,Jundong Xu,Lijun Li
Visible light-mediated photoinduced reversible addition-fragmentation chain transfer polymerization (RAFT) copolymerization of 1,3-pentadiene isomers and maleic anhydride (MAH) in the absence of photocatalysts or photoinitiators was realized in tetrahydrofuran (THF) solvent at r.t. under various visible wavelengths. The well-defined alternating copolymers were successfully and efficiently synthesized by directly using O -ethyl- S -benzoic thioanhydride ( EBT ) as chain transfer agent activated by blue light (460 nm). The conventional thermal-initiated radical copolymerization of 1,3-pentadiene (PD) isomers (except cis -1,3-pentadiene (CP)) and MAH gave both DA cycloaddition products and alternating sequence copolymers. In contrast, the alternating copolymer was the only isolated product in this photoinitiated polymerization system, in which the DA reaction was completely suppressed. Moreover, both trans -1,3-pentadiene (TP) and PD isomers can be copolymerized with MAH to give alternating copolymers with high yields up to 100%, although the photopolymerization rates are in the order: PD > CP > TP. And the copolymerization can be implemented by simply switching the light source ON/OFF. We supposed that the donor–acceptor interaction between the PD and MAH (similar to St (styrene)/MAH system) plays an important role in this novel light-induced RAFT alternating copolymerization behavior.
研究领域:
高分子化学
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材料科学
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JOURNAL OF POLYMER RESEARCH
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2023
·Vol. 30
·期 8
·1-12
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IF 2.8
Xiong Qiaoqiao,Yang Shuai,Peng Chengjun,Xie Fengli,Gu Zhuowei,Fu Yawen,Tan Haoyun,Dai QiQi,Yi Wenjun,Li Lijun,Liu Kun
Styrene/1,3-diene copolymers are widely used in rubber tires, adhesives, waterproof materials, automotive parts and others. However, their oil resistance, compatibility with polar materials, and poor adhesion limit their applications. Polarization modification strategy can further expand the application field of such materials. In this paper, a series of strictly alternating copolymers were synthesized in cyclohexane via living and controlled anionic alternating copolymerization of styrene derivatives (including styrene (ST), p -methylstyrene (MST), p -tert-butylstyrene (TBS), and 1,1-diphenylethylene (DPE)) with 1,3-pentadiene (PD) using n -BuLi initiator. The above-mentioned alternating copolymers were epoxidized in cycloamyl methyl ether (CPME, green solvent) using m -Chloroperoxybenzoic acid ( m -CPBA) as the oxygen source. The 1 H NMR and FTIR results showed that the degree of epoxidation ( DE ) of the alternating copolymers was controllable and the cross-linking gels can be avoided (determined by solubility experiment), and the DE of nearly 100% could be achieved by optimizing processes. As for these PD-based alternating copolymers, the type of substituents on rigid benzene rings has a certain impact on the epoxidation rate as well as the DE . DSC results showed that not only the high steric hindrance groups in polymer side chains but also the epoxidation strategy can greatly improve the heat resistance of the product.
研究领域:
材料科学
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化学工程
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高影响因子
POLYMER
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2024
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IF 4.1
Haoyun Deng,Zhixiong Yang,Mengzhen Zhou,Encai Ou,Yanbing Lu,Qiulan Zhou,Kun Liu,Weijian Xu
( Z )-1,3-pentadiene (Zp) exhibits a rigid planar molecular structure and is known for the typical 1,5-sigmatropic hydrogen shift, while it is commonly considered an inert monomer during polymerization. Herein, by utilizing the steric effect of the terminal methyl in Zp, the high trans -1,4-polypentadiene (HTPD) with highly ordered microstructure and well-defined sequence are successfully synthesized using barium dithymol/ tert- butyllithium/ tri -ethylaluminum trimetallic initiators based on anionic polymerization. The significant dependence of polymerization rate and trans -1,4-selectivity on ratio of Ba/Al/Li is demonstrated. The modification in microstructure ( trans -1,4 content ranging from 75 % to 92 %) and stereo-regularity (isotactic triad mm % > 65 %) are confirmed by nuclear magnetic resonance (NMR). Compared with the poly(( Z )-1,3-pentadiene) (PZp) prepared by n -BuLi containing σ -ligand modifiers, the strategy using a large steric initiator to achieve regular insertion of Zp into polymer chains is proved to be effective. Kinetics studies demonstrated that Ba–Al–Li system is characterized by retarded anionic polymerization (RAP), yet it shows a quasi-living process and enabling the preparation of stereometric block polymers such as polyisoprene- b -HTPD (PI- b -HTPD). Thermal performance analysis indicates that the obtained highly ordered polymers show superior thermoplastic properties ( T m = 77.4 °C) with crystallinity as an elastomer. Furthermore, reasonable interpretations for the structure formation, sequence, and rate reduction effected by the Ba/Al/Li trimetallic initiator are proposed.
研究领域:
高分子化学
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材料科学
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APPLIED CATALYSIS A-GENERAL
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2022
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IF 5.723
Ruilin Feng,Yanlong Qi,Shijun Liu,Long Cui,Quanquan Dai,Chenxi Bai
1,3-Pentadiene plays an extremely important role in the production of polymers and fine chemicals. Herein, the LaPO 4 catalyst exhibits excellent catalytic performance for the dehydration production of 1,3-pentadiene with 2,3-pentanediol, a C5 diol platform compound that can be easily obtained by hydrogenation of bio-based 2,3-pentanedione. The relationships of catalyst structure-acid/base properties-catalytic performance was established, and an acid-base synergy effect was disclosed for the on-purpose synthesis of 1,3-pentadiene. Thus, a balance between acid and base sites was required, and an optimized LaPO 4 with acid/base ratio of 2.63 afforded a yield of 1,3-pentadiene as high as 61.5% at atmospheric pressure. Notably, the Brønsted acid sites with weak or medium in LaPO 4 catalyst can inhibit the occurrence of pinacol rearrangement, resulting in higher 1,3-pentadiene production. In addition, the investigation on reaction pathways demonstrated that the E2 mechanism was dominant in this dehydration reaction, accompanied by the assistance of E1 and E1cb.
研究领域:
化学工程
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催化
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可再生化学
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有机合成
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DOI
高影响因子
危险品化学品经营许可证（带存储）