CHEMICAL ENGINEERING SCIENCE
·
2016
·
IF 2.75
Genkuo Nie,Xiangwen Zhang,Peijuan Han,Junjian Xie,Lun Pan,Li Wang,Ji-Jun Zou
Biofuels are important alternative for fossil-based fuel but they have either relatively low density or high freezing point and viscosity. Here we reported a simple and efficient route to synthesis biofuel with density comparable to widely used JP-10 fuel as well as good low-temperature properties. Substituted diphenyl methane was synthesized by acid catalytic alkylation of lignin-derived phenols (phenol, anisole, guaiacol) with benzyl ether or benzyl alcohols, and MMT-K10 exhibits better activity than HPW, Amberlyst-15, and Al-MCM-41, due to the modest acid strength and open lamellar structure. High selectivity along with good-to-excellent conversion was obtained under optimized conditions regardless of different reactant used. Then the alkylated product was subjected to hydrogenation with the presence of Pd/C and HZSM-5, and interestingly, intramolecular cyclization reaction occurred to produce a large amount of perhydrofluorene as well as dicyclohexylmethane. Subsequently, biofuel with density as high as 0.93 g/mL and freezing point as low as −40.0 °C was obtained, which surpasses the state-of-art of biofuel reported.
研究领域:
化学工程
·
能源科学
·
生物化学
✓ 已验证
产品关联
DOI
高影响因子
ORGANIC & BIOMOLECULAR CHEMISTRY
·
2020
·Vol. 18
·期 21
·4034-4045
·
IF 3.412
Ming-Hong Liao,Meng Zhang,Dai-Hui Hu,Rui-Han Zhang,Yan Zhao,Shan-Shan Liu,Yun-Xia Li,Wei-Lie Xiao,E Tang
An efficiently divergent intramolecular Friedel–Crafts alkylation by unactivated alkenes with seleniranium ion-controlled Markovnikov/anti-Markovnikov specificities under mild conditions has been investigated. 2-Benzoxepin, isochroman, and isochromene can be produced in one-pot procedures from the same substrate in high yields and with high regio- and stereospecificity. The products are challenging to access via 7-endo-trig carbocyclizations and by 7-endo-trig carbocyclization/rearrangement/6-exo-trig oxycyclization and 6-exo-trig carbocyclization/deselenenylation reaction sequences, respectively. Mechanistic experiments indicated that in addition to the stereospecific anti-addition processes of the cyclization reactions, the formation of a stable carbocation after ring opening of the seleniranium ion leads to an NPSP-mediated 7-endo-trig carbocyclization; the steric hindrance of the seleniranium intermediate controls the regioselectivity when using TPSCA at 60 °C, which promotes 6-exo-trig carbocyclization. Two distinct catalytic cycles were proposed, and the structures of transition states and products were identified by ab initio calculations and X-ray analyses.
研究领域:
有机化学
·
催化化学
✓ 已验证
DOI
PubMed
高影响因子
ORGANIC & BIOMOLECULAR CHEMISTRY
·
2025
·
IF 2.7
Fei Yuan,Yiyuan Xin,Caifeng Yuan,Zhuo Chen,Tongling Qin,Wenxia Hu,Jiahuan Duan,E Tang
A simple, exogenous-base-free, and NBS-mediated C-selenocyanation/cyclization reaction of enaminones with KSeCN under mild conditions, providing a facile route to 2-aminoselenazole products, has been developed. This efficient protocol is postulated to first undergo the NBS-oxidated polarity reversal of the reactive SeCN- anion to form N-selenocyanosuccinimide as an electrophilic selenium source, which can induce the C-selenocyanation of enaminones and enamino esters, followed by a nucleophilic cyclization promoted by in-situ yielded HBr.
研究领域:
有机化学
·
合成化学
·
硒化学
✓ 已验证
DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2019
·Vol. 10
·期 3
·736-741
·
IF 5.726
Shaorui Yan,Ruinian Zhou,Feng Han,Mengmeng Feng,Chengxia Miao,Shuai Zhang,Shiyun Ai
A CO2-induced ROCO2Na/ROCO2H buffer solution is developed and employed in the carboxylative cyclization of propargyl alcohol to generate α-alkylene cyclic carbonates. The introduction of CO2 into the propargyl alcohol/sodium tertiary pentoxide system can provide the ROCO2Na/ROCO2H buffer solution with both basic and acidic species. The basic and acidic species can simultaneously promote the generation of a carbonate anion intermediate and the interaction between the alkyne moieties of propargyl alcohol and protons (H+), facilitating carboxylative cyclization. Furthermore, the bulky (n-C4H9)4N+ cation of tetrabutylammonium bromide as an additive plays a crucial role in enhancing the nucleophilicity of the carbonate anion intermediate. Various α-alkylene cyclic carbonates are obtained in this catalytic system with relatively good yields at 80 °C.
研究领域:
化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
BIOCHEMISTRY
·
2016
·
IF 2.876
Zhenqiu Li,Ruiping Gao,Qinggang Hao,Huifang Zhao,Longbin Cheng,Fang He,Li Liu,Xiuhua Liu,Wayne K. W. Chou,Huajie Zhu,David E. Cane
The T296V mutant of amorpha-4,11-diene synthase catalyzes the abortive conversion of the natural substrate (E,E)-farnesyl diphosphate mainly into the acyclic product (E)-β-farnesene (88%) instead of the natural bicyclic sesquiterpene amorphadiene (7%). Incubation of the T296V mutant with (3R,6E)-nerolidyl diphosphate resulted in cyclization to amorphadiene. Analysis of additional mutants of amino acid residue 296 and in vitro assays with the intermediate analogue (2Z,6E)-farnesyl diphosphate as well as (3S,6E)-nerolidyl diphosphate demonstrated that the T296V mutant can no longer catalyze the allylic rearrangement of farnesyl diphosphate to the normal intermediate (3R,6E)-nerolidyl diphosphate, while retaining the ability to cyclize (3R,6E)-nerolidyl diphosphate to amorphadiene. The T296A mutant predominantly retained amorphadiene synthase activity, indicating that neither the hydroxyl nor the methyl group of the Thr296 side chain is required for cyclase activity.
研究领域:
植物生物学
·
分子生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
TETRAHEDRON
·
2017
·
IF 2.651
Yanmin Yao,Xiaobin Wang,Guangxin Liang
We report concise asymmetric total syntheses of tetracyclic marine alkaloids (+)-agelastatin A and (+)-agelastatin B using a cationic cyclization-based approach, which features straightforward transformations with cost-effective chemicals and reagents.
研究领域:
有机化学
·
药物化学
✓ 已验证
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
·
2025
·Vol. 32
·期 2
·1-13
·
IF 2.8
Wang Chaoying,Xin Zhong
In this work, polyacrylonitrile (PAN) homopolymer, poly(acrylonitrile-methyl acrylate)[P(AN-MA)], poly(acrylonitrile-methyl acrylate-itaconic acid)[P(AN-MA-IA)] and poly(acrylonitrile-methyl acrylate-ammonium itaconic acid)[P(AN-MA-AIA)] with narrow polydispersity were successfully produced in continuous flow. The compositions, molecular weights, molecular weight distributions and crystalline structures of these PAN polymers were measured and the influence of IA and AIA on cyclization reactions, structural transformation and thermal stability during the stabilization process was also explored. The incorporation of IA and AIA into polymer chains reduces the initial temperatures of cyclization reactions, broadens the exothermic peaks, eases the concentrated heat through an ionic mechanism and exhibits better stabilization at lower temperatures. Furthermore, AIA effectively promotes dehydrogenation reaction. Among these four PAN polymers, P(AN-MA-AIA) terpolymer presents the best stabilization since COO − NH 4 + has the strongest nucleophilicity towards nitrile groups that are close to carbon atoms.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ORGANIC CHEMISTRY
·
2025
·
IF 3.6
Haoyang Liu,Hailiang Xing,Peilan Yu,Yanjie Wang,Jia-Lei Yan,Junyang Liu,Min Wang
A facile copper-catalyzed, base-controlled cyclization reaction has been developed for the synthesis of 9-membered cycloalkyne and 6-membered heterocycle sultams under mild conditions. This protocol utilizes a copper-catalyzed intramolecular A3 (alkyne–aldehyde–amine) coupling reaction to efficiently synthesize 9-membered cycloalkyne sultams in yields up to 90%. Alternatively, by substituting NaHCO3 with DBU, the protocol achieves selective deprotection of the N-propargyl group, thereby facilitating the formation of 6-membered heterocyclic sultams, also in high yields.
研究领域:
有机化学
·
合成化学
✓ 已验证
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2020
·
IF 3.573
Yangfeng Xia,Xing Zhang,Long Liu,Haiyun Sun,Guoying Zhao,Yanqiang Zhang
Pyrazoline derivatives as valuable five-membered heterocyclic compounds could be readily prepared through the intramolecular cyclization of ketazines. In this paper, transition metals (Zn2+, Cu2+, Cr3+, Mn2+, Co2+, Ni2+, and Fe3+) were applied for the catalytic synthesis of 3,5,5-trimethyl-2-pyrazoline, and FeCl3 showed the best catalytic performance with 95% conversion and 99% selectivity. Substrate screening exhibited that the steric hindrance of ketazines is a key factor on the conversions of R-substituted pyrazolines, following the order of R as methyl (95%) > ethyl (83%) > propyl (68%) > butyl (55%). Moreover, the mechanism of the cyclization of ketazines catalyzed by FeCl3 is calculated by density functional theory. The energetic profile shows that the cyclization reaction consists of two steps and FeCl3 can efficiently reduce their barrier energies. This work provides a feasible method for the preparation of pyrazoline derivatives using inexpensive, less toxic, and environmentally friendly FeCl3 as a catalyst.
研究领域:
有机化学
·
催化化学
·
理论化学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER
·
2020
·
IF 4.231
Sheng-Qi Chen,Chen He,Gang Song,Lianwei Li,Hui-Juan Li,Abdul Haleem,Wei-Dong He
Cyclization has been widely reported to compete with interchain growth and lead to limited degree of polymerization in step-growth polymerization of AB 2 monomers . However, little attention has been paid to kinetical comparison between interchain growth and cyclization in preparation of long-subchain hyperbranched polymers (LHPs) from AB 2 macromonomers in semi-dilute solution. This work aims to elucidate how cyclization influences the polymerization of AB 2 macromonomers via kinetical competition with interchain growth and how molar mass of macromonomer affects this competition. The corresponding kinetics in semi-dilute solution is theoretically derived in consideration of cyclization. For a given mass concentration, interchain growth rate ( r g ), cyclization rate ( r c ) and their ratio ( r g / r c ) highly depend on the molar mass of macromonomer (M), following the scale rule of r g ∝ M − 2 , r c ∝ M − 2.5 and r g / r c ∝ M 0.5 , respectively. It indicates that macromonomers with lower molar mass tend to generate products with lower degree of polymerization in terms of macromonomer ( DP macromonomer ) and higher self-cyclized macromonomer ratio (CMMR) at a faster rate, while macromonomers with higher molar mass act oppositely. These proposed theories are further verified via the experimental investigation about the step-growth of AB 2 polystyrene (PSt) macromonomers with different molar masses. The structural analyses of the resultant products from PSt macromonomers with a low molar mass of 2.5 k indicate a very low DP macromonomer with a nearly complete conversion of focal A groups, which implies predominant position of cyclized compositions in resultant products, not only cyclized macromonomers (CMMs) but also cyclized long-subchain hyperbranched polymers (CLHPs). More importantly, experimental results show that conversion rate and CMMR increase but DP macromonomer decreases sharply as molar mass of macromonomer decreases, which quite agrees with the theoretical inference.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULES
·
2016
·
IF 5.554
Shaoning Liang,Xiaohui Li,Wen-Jun Wang,Bo-Geng Li,Shiping Zhu
We report the reversible addition–fragmentation chain transfer (RAFT) solution copolymerization of methyl methacrylate (MMA) with a cleavable divinyl comonomer, bis(2-methacryloyl)oxyethyl disulfide (BMAODS). 2-Cyano-2-propyldodecyl trithiocarbonate was used as a RAFT chain transfer agent and 2,2′-azobis(2-methylpropionitrile) as an initiator. The selective cleavage of BMAODS disulfide bonds was used to collect primary chains for the determination of the branching density (BD). The effects of initial monomer concentration, vinyl/divinyl ratio, and primary chain length on the branching and cyclization reactions were thoroughly investigated. It was found that more than 50% pendent double bonds from BMAODS were consumed in cyclization rather than in branching. The BD increased linearly with the conversion up to approximately 60% conversion. The monomer concentration was found to be the most efficient parameter in promoting branching. Increasing divinyl monomer ratio and primary chain length favored cyclization over branching. The work provides experimental evidence to support the random branching mechanism in RAFT copolymerization of vinyl and divinyl monomers.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER TESTING
·
2019
·
IF 2.943
Zhuo Cao,Weijie Li,Xidong Suo,Yaodong Liu,Chunxiang Lu
Polyacrylonitrile (PAN)/cellulose composite fibers have been produced by dry-jet gel spinning through their co-solution. The rheological properties of PAN/cellulose/dimethylacetamide/LiCl solutions containing different cellulose contents from 0 to 10 wt% were characterized, and 5 wt% PAN/cellulose composite solution shows the best solution homogeneity. During gel spinning, the cellulose forms elongated particles inside the gelation bath, and the particle diameters depend on the as-spun draw ratio. It was found that the glass transition of PAN fibers shifts to higher temperatures along with the increase of cellulose content, and the glass transition activation energy of PAN chains becomes higher when cellulose particles become smaller. Regardless the changes of cellulose amount (2–10 wt%) and particle diameter (7.1–1.4 μm), the cyclization activation energy of PAN/cellulose composite fibers is 13–17% lower than that of neat PAN fibers. Our experiments suggest that the addition of cellulose in PAN fibers has no direct effect on the cyclization reaction of PAN chains. Instead, the released by-products during the pyrolysis of cellulose at high temperature degradation affect the cyclization reaction of PAN chains.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）