Continuous-flow upgrading of pentaerythritol synthesis technology via base-catalyzed aldol and Cannizzaro reactions of formaldehyde and acetaldehyde faces the challenge of effectively controlling the critical side rea...Continuous-flow upgrading of pentaerythritol synthesis technology via base-catalyzed aldol and Cannizzaro reactions of formaldehyde and acetaldehyde faces the challenge of effectively controlling the critical side reaction of hydroxymethyl acetaldehyde(HA)to the acrolein intermediate.Here,we first identified the forms of industrial formaldehyde as methane diol that easily converts to the alkaline formaldehyde under alkaline(NaOH)environment.The carbonyl group of alkaline formaldehyde induces deprotonation of acetaldehyde instead of the recognized base-hydroxyl group-induced deprotonation,and it needs to overcome only 18.31 kcal·mol^(-1)(1 kcal=4.186 kJ)energy barrier to form key intermediates of HA.The sodium solvation cage formed by NaOH hexa-coordinated formaldehyde effectively inhibits the alkalinity,thus contributing to a high energy barrier(46.21 kcal·mol^(-1))to unwanted acrolein formation.In addition,the solvation cage gradually opens to increase the alkalinity with the consumption of formaldehyde,thus facilitating the subsequent Cannizzaro reaction(to overcome 11.77 kcal·mol^(-1)).In comparison,strong alkalinity promotes the formation of acrolein(36.65 kcal·mol^(-1))to initiate the acetal side reaction,while weak alkalinity reduces the possibility of the Cannizzaro reaction(to overcome 20.44 kcal·mol^(-1)).This theoretically reveals the importance of the segmented feeding of weak and strong bases to successively control the aldol reaction and Cannizzaro reaction,and the combination of Na_(2)CO_(3) or HCOONa with NaOH improves the pentaerythritol yield by 7%to 13%compared to that of NaOH alone(70%yield)within 1 min at a throughput of 155.7 ml·min^(-1).展开更多
To improve the flame-retardant efficiency and water resistance of ammonium polyphosphate（APP）, the UV-curable pentaerythritol triacrylate（PETA） was used to microencapsulate APP via the UV curing polymerization met...To improve the flame-retardant efficiency and water resistance of ammonium polyphosphate（APP）, the UV-curable pentaerythritol triacrylate（PETA） was used to microencapsulate APP via the UV curing polymerization method. The prepared PETA-microencapsulated APP（PETA-APP） was characterized by Fourier transform infrared spectroscopy（FTIR）, scanning electron microscopy（SEM）, and thermogravimetric（TG） analysis. PETA-APP was used as intumescent flame retardant（IFR） alone to flame retard polypropylene（PP）. The water resistance of PP/PETA-APP composites was investigated, and the effect of PETA on the combustion behaviors of PP/APP composites was studied through limiting oxygen index（LOI）, vertical burning test（UL-94） and cone calorimeter（CC） test, respectively. With 40 wt% of PETA-APP, the PP/PETA-APP system could achieve a LOI value of 30.0% and UL-94 V-0 rating after treatment in hot water for 168 h, while the LOI value of the system containing 40 wt% uncoated APP was only 19.2%, and it failed to pass the UL-94 rating. CC test results showed that the heat release rate（HRR）, mass loss rate（MLR） and smoke production rate（SPR） of PP/PETAAPP system decreased significantly compared with PP/APP system, especially the peak of HRR was decreased by 51.4%. The mechanism for the improvement of flame reatardancy for PP/PETA-APP composites was discussed based on FTIR and X-ray photoelectron spectroscopy（XPS） tests. All these results illustrated that simultaneous improvement of flame retardancy and water resistance for PP/APP was achieved through coating UV-curable PETA onto APP.展开更多
In this article,an efficient,simple and environmentally friendly approach to the synthesis of diacetals(diketals)pentaerythritol using SOH-functionalized ionic liquids(ILs)as catalysts was reported.The ILs show high c...In this article,an efficient,simple and environmentally friendly approach to the synthesis of diacetals(diketals)pentaerythritol using SOH-functionalized ionic liquids(ILs)as catalysts was reported.The ILs show high catalytic activity and reusability with good to excellent yields of the desired products.Hammett method has been used to determine the acidity order of these ionic liquids and the results are consistent with the catalytic activities observed in acetalization reaction.Maximum product yield of 93%was observed on using[PSPy][OTf]as catalyst and it can be reused at least 8 times without obvious activity loss.展开更多
Pentaerythritol triacrylate （PETA） was successfully grafted onto the plasma-treated isotactic polypropylene （iPP） via the in situ melt processing. The X-ray photoelectron spectroscopy （XPS） results showed that t...Pentaerythritol triacrylate （PETA） was successfully grafted onto the plasma-treated isotactic polypropylene （iPP） via the in situ melt processing. The X-ray photoelectron spectroscopy （XPS） results showed that the hydroxyl and carbonyl groups, and peroxides could be generated via plasma treatment. The content of free radical in plasma-treated iPP （PiPP） was measured by 2,2-diphenyl-1- picrylhydrazyl （DPPH）. It was found that the resulting peroxides induced the grafting copolymerization of PETA onto iPP, and the grafted PETA promoted the formation of β-crystal in PiPP, which was evidenced by Fourier transform infrared spectroscopy （FTIR）, differential scanning calorimetry （DSC） and wide-angle X-ray diffraction （WAXD） measurements, respectively.展开更多
Pentaerythritol（PET） crystal has been grown rapidly from the solution with sulfuric acid as the additive. The growth rate of PET crystal in prismatic shape exceeds 1.5 mm/day and crystallization size is 55×55&#...Pentaerythritol（PET） crystal has been grown rapidly from the solution with sulfuric acid as the additive. The growth rate of PET crystal in prismatic shape exceeds 1.5 mm/day and crystallization size is 55×55×50 mm^3. X-ray diffraction analysis was used to confirm the structure integrity. The diffraction efficiency of rapid-grown crystal was characterized as effective as that of normal growth.展开更多
A series of novel pentaerythritol-based carbosilane dendrimers have been synthesized. Using pentaerythritol-based tetraallyl ether as core molecule, the dendrimers have been prepared up to the third generation with 10...A series of novel pentaerythritol-based carbosilane dendrimers have been synthesized. Using pentaerythritol-based tetraallyl ether as core molecule, the dendrimers have been prepared up to the third generation with 108 allyl groups on the periphery by alternate allylation-hydro- silylation approach.展开更多
A novel liquid crystalline dendrimer with peripheral mesogenic units was successfully prepared. Azo-reaction and Williamson synthesis were employed in the preparation of the mesogenic unit 4-[4-(6-hydroxyhexyloxy)-phe...A novel liquid crystalline dendrimer with peripheral mesogenic units was successfully prepared. Azo-reaction and Williamson synthesis were employed in the preparation of the mesogenic unit 4-[4-(6-hydroxyhexyloxy)-phenylazo]nitrobenzene (M-NO2). A terminal Si—Cl functional carbosilane dendrimer based on pentaerythritol was used as dendritic scaffold and subsequently functionalized with the aforementioned groups. Investigation of the liq-uid crystalline properties of the mesogen-functionalized dendrimer PCSi-1G-NO2 by polarizing optical microscopy, DSC, and X-ray diffraction showed that it exhibits smectic E (SE) phase, different from the corresponding mesog-enic unit, which shows nematic phase. Furthermore, the temperatures of both the melting point and the clearing point of the mesogen-functionalized dendrimer decrease, and the temperature region of the SE phase is wider than that of the nematic phase.展开更多
This paper reports a practical and green method for the acetalization of carbonyl compounds as pentaerythritol diacetals and diketals derivatives using cellulose sulfuric acid as a biodegradable and reusable solid aci...This paper reports a practical and green method for the acetalization of carbonyl compounds as pentaerythritol diacetals and diketals derivatives using cellulose sulfuric acid as a biodegradable and reusable solid acid catalyst under thermal solvent-free conditions.展开更多
为了显著提升聚对苯二甲酸乙二醇酯(PET)纤维的柔软性和亲水性能,采用聚乙二醇(PEG)与季戊四醇(PER)作为共聚改性单体,通过与对苯二甲酸和乙二醇的酯化-缩聚反应制备系列共聚酯,并采用熔融纺丝工艺制备改性纤维。采用核磁共振氢谱表征...为了显著提升聚对苯二甲酸乙二醇酯(PET)纤维的柔软性和亲水性能,采用聚乙二醇(PEG)与季戊四醇(PER)作为共聚改性单体,通过与对苯二甲酸和乙二醇的酯化-缩聚反应制备系列共聚酯,并采用熔融纺丝工艺制备改性纤维。采用核磁共振氢谱表征化学结构,使用差示扫描量热法和热重分析测试热性能,并通过单丝强力仪评估纤维性能。结果表明:当PEG质量分数为20%、PER质量分数为0.1%时,共聚酯仍保持较好的热稳定性,熔点为236.9℃,起始分解温度达372.7℃;纤维力学性能测试显示,断裂强度达2.09 c N/dtex,断裂伸长率为28.3%,仍具有良好的可纺性。与未改性PET纤维相比,改性纤维的柔软性显著提升(相对弯曲刚度降低65%),吸湿性明显改善(回潮率从0.4%提高到1.10%,增幅达175%)。该研究为开发兼具高柔软性和高亲水性的仿棉聚酯纤维提供了一种有效的策略。展开更多
Novel pentaerythritol-based carbosilane dendrimers centered at carbon have been synthesised. Starting from tetraallyl ether based upon pentaerythritol as the core molecule, a succession of alternate Pt-catalyzed hydro...Novel pentaerythritol-based carbosilane dendrimers centered at carbon have been synthesised. Starting from tetraallyl ether based upon pentaerythritol as the core molecule, a succession of alternate Pt-catalyzed hydrosilyla-tion of allyl groups with HSiCl3 and allylations of SiCl groups thus introduced with CH2=CHCH2MgBr in THF provided a divergent synthesis of three generations of carbosilane dendrimers in which the Si atoms are linked by CH2CH2CH2 groups. The reaction conditions for hydrosilylation must be well controlled. After purification by chromatography on silica gel pure products for each generation were obtained. The IR, 1H and 13C NMR spectra and elemental analysis data are consistent with the proposed structures. The molecular weights of the resulting car-bosilne dendrimers have been determined by vapor pressure osmometry.展开更多
基金funded by the National Natural Science Foundation of China(22478632)Key Scientific and Technological Project of Henan Province(242102321032).
文摘Continuous-flow upgrading of pentaerythritol synthesis technology via base-catalyzed aldol and Cannizzaro reactions of formaldehyde and acetaldehyde faces the challenge of effectively controlling the critical side reaction of hydroxymethyl acetaldehyde(HA)to the acrolein intermediate.Here,we first identified the forms of industrial formaldehyde as methane diol that easily converts to the alkaline formaldehyde under alkaline(NaOH)environment.The carbonyl group of alkaline formaldehyde induces deprotonation of acetaldehyde instead of the recognized base-hydroxyl group-induced deprotonation,and it needs to overcome only 18.31 kcal·mol^(-1)(1 kcal=4.186 kJ)energy barrier to form key intermediates of HA.The sodium solvation cage formed by NaOH hexa-coordinated formaldehyde effectively inhibits the alkalinity,thus contributing to a high energy barrier(46.21 kcal·mol^(-1))to unwanted acrolein formation.In addition,the solvation cage gradually opens to increase the alkalinity with the consumption of formaldehyde,thus facilitating the subsequent Cannizzaro reaction(to overcome 11.77 kcal·mol^(-1)).In comparison,strong alkalinity promotes the formation of acrolein(36.65 kcal·mol^(-1))to initiate the acetal side reaction,while weak alkalinity reduces the possibility of the Cannizzaro reaction(to overcome 20.44 kcal·mol^(-1)).This theoretically reveals the importance of the segmented feeding of weak and strong bases to successively control the aldol reaction and Cannizzaro reaction,and the combination of Na_(2)CO_(3) or HCOONa with NaOH improves the pentaerythritol yield by 7%to 13%compared to that of NaOH alone(70%yield)within 1 min at a throughput of 155.7 ml·min^(-1).
基金financially supported by the National Natural Science Foundation of China(Nos.50933005,51121001)the Program for Changjiang Scholars and Innovative Research Team in Universities(IRT1026)
文摘To improve the flame-retardant efficiency and water resistance of ammonium polyphosphate（APP）, the UV-curable pentaerythritol triacrylate（PETA） was used to microencapsulate APP via the UV curing polymerization method. The prepared PETA-microencapsulated APP（PETA-APP） was characterized by Fourier transform infrared spectroscopy（FTIR）, scanning electron microscopy（SEM）, and thermogravimetric（TG） analysis. PETA-APP was used as intumescent flame retardant（IFR） alone to flame retard polypropylene（PP）. The water resistance of PP/PETA-APP composites was investigated, and the effect of PETA on the combustion behaviors of PP/APP composites was studied through limiting oxygen index（LOI）, vertical burning test（UL-94） and cone calorimeter（CC） test, respectively. With 40 wt% of PETA-APP, the PP/PETA-APP system could achieve a LOI value of 30.0% and UL-94 V-0 rating after treatment in hot water for 168 h, while the LOI value of the system containing 40 wt% uncoated APP was only 19.2%, and it failed to pass the UL-94 rating. CC test results showed that the heat release rate（HRR）, mass loss rate（MLR） and smoke production rate（SPR） of PP/PETAAPP system decreased significantly compared with PP/APP system, especially the peak of HRR was decreased by 51.4%. The mechanism for the improvement of flame reatardancy for PP/PETA-APP composites was discussed based on FTIR and X-ray photoelectron spectroscopy（XPS） tests. All these results illustrated that simultaneous improvement of flame retardancy and water resistance for PP/APP was achieved through coating UV-curable PETA onto APP.
基金supported by National 863 High-Tech Research and Development Program of China(No. 2007AA05Z101)
文摘In this article,an efficient,simple and environmentally friendly approach to the synthesis of diacetals(diketals)pentaerythritol using SOH-functionalized ionic liquids(ILs)as catalysts was reported.The ILs show high catalytic activity and reusability with good to excellent yields of the desired products.Hammett method has been used to determine the acidity order of these ionic liquids and the results are consistent with the catalytic activities observed in acetalization reaction.Maximum product yield of 93%was observed on using[PSPy][OTf]as catalyst and it can be reused at least 8 times without obvious activity loss.
基金financially supported by the National Natural Science Foundation of China (No.51473113)the Natural Science Foundation of Tianjin (No.12JCYBJC11900)
文摘Pentaerythritol triacrylate （PETA） was successfully grafted onto the plasma-treated isotactic polypropylene （iPP） via the in situ melt processing. The X-ray photoelectron spectroscopy （XPS） results showed that the hydroxyl and carbonyl groups, and peroxides could be generated via plasma treatment. The content of free radical in plasma-treated iPP （PiPP） was measured by 2,2-diphenyl-1- picrylhydrazyl （DPPH）. It was found that the resulting peroxides induced the grafting copolymerization of PETA onto iPP, and the grafted PETA promoted the formation of β-crystal in PiPP, which was evidenced by Fourier transform infrared spectroscopy （FTIR）, differential scanning calorimetry （DSC） and wide-angle X-ray diffraction （WAXD） measurements, respectively.
基金supported by Key Laboratory of Optoelectronic Materials Chemistry and Physics,Chinese Academy of Sciences (2009KL007)
文摘Pentaerythritol（PET） crystal has been grown rapidly from the solution with sulfuric acid as the additive. The growth rate of PET crystal in prismatic shape exceeds 1.5 mm/day and crystallization size is 55×55×50 mm^3. X-ray diffraction analysis was used to confirm the structure integrity. The diffraction efficiency of rapid-grown crystal was characterized as effective as that of normal growth.
基金This work was supported by the National Natural Science Foundation of China(No.29874020,59573029).
文摘A series of novel pentaerythritol-based carbosilane dendrimers have been synthesized. Using pentaerythritol-based tetraallyl ether as core molecule, the dendrimers have been prepared up to the third generation with 108 allyl groups on the periphery by alternate allylation-hydro- silylation approach.
基金the National Natural Science Foundation of China (Nos.29874020 and 59573029).
文摘A novel liquid crystalline dendrimer with peripheral mesogenic units was successfully prepared. Azo-reaction and Williamson synthesis were employed in the preparation of the mesogenic unit 4-[4-(6-hydroxyhexyloxy)-phenylazo]nitrobenzene (M-NO2). A terminal Si—Cl functional carbosilane dendrimer based on pentaerythritol was used as dendritic scaffold and subsequently functionalized with the aforementioned groups. Investigation of the liq-uid crystalline properties of the mesogen-functionalized dendrimer PCSi-1G-NO2 by polarizing optical microscopy, DSC, and X-ray diffraction showed that it exhibits smectic E (SE) phase, different from the corresponding mesog-enic unit, which shows nematic phase. Furthermore, the temperatures of both the melting point and the clearing point of the mesogen-functionalized dendrimer decrease, and the temperature region of the SE phase is wider than that of the nematic phase.
文摘This paper reports a practical and green method for the acetalization of carbonyl compounds as pentaerythritol diacetals and diketals derivatives using cellulose sulfuric acid as a biodegradable and reusable solid acid catalyst under thermal solvent-free conditions.
文摘为了显著提升聚对苯二甲酸乙二醇酯(PET)纤维的柔软性和亲水性能,采用聚乙二醇(PEG)与季戊四醇(PER)作为共聚改性单体,通过与对苯二甲酸和乙二醇的酯化-缩聚反应制备系列共聚酯,并采用熔融纺丝工艺制备改性纤维。采用核磁共振氢谱表征化学结构,使用差示扫描量热法和热重分析测试热性能,并通过单丝强力仪评估纤维性能。结果表明:当PEG质量分数为20%、PER质量分数为0.1%时,共聚酯仍保持较好的热稳定性,熔点为236.9℃,起始分解温度达372.7℃;纤维力学性能测试显示,断裂强度达2.09 c N/dtex,断裂伸长率为28.3%,仍具有良好的可纺性。与未改性PET纤维相比,改性纤维的柔软性显著提升(相对弯曲刚度降低65%),吸湿性明显改善(回潮率从0.4%提高到1.10%,增幅达175%)。该研究为开发兼具高柔软性和高亲水性的仿棉聚酯纤维提供了一种有效的策略。
基金Project supported by the National Natural Science Foundation of China (Nos. 29874020,59573029).
文摘Novel pentaerythritol-based carbosilane dendrimers centered at carbon have been synthesised. Starting from tetraallyl ether based upon pentaerythritol as the core molecule, a succession of alternate Pt-catalyzed hydrosilyla-tion of allyl groups with HSiCl3 and allylations of SiCl groups thus introduced with CH2=CHCH2MgBr in THF provided a divergent synthesis of three generations of carbosilane dendrimers in which the Si atoms are linked by CH2CH2CH2 groups. The reaction conditions for hydrosilylation must be well controlled. After purification by chromatography on silica gel pure products for each generation were obtained. The IR, 1H and 13C NMR spectra and elemental analysis data are consistent with the proposed structures. The molecular weights of the resulting car-bosilne dendrimers have been determined by vapor pressure osmometry.
