Swelling acidic poly(ionic liquid)s as efficient catalysts for the esterification of cyclohexene and formic acid

Acidic poly(ionic liquid)s(PILs)with swelling ability were synthesized by free radical copolymerization of N-vinylimidazolium ionic liquids,divinylbenzene(DVB)and sodium acrylate(NaAA),and further acidification by sulfuric acid.The swelling ability of acidic PILs was greatly affected by cross-linker content and chain length of 3-alkyl-substituents on imidazolium.Cross-linked network structures could be observed from the cryogenic scanning electron microscopy(cryo-SEM)images of the swollen acidic PILs in formic acid.Acidic PILs with network structures in swollen state exhibited excellent activities in the esterification of cyclohexene and formic acid,and the catalytic activities were in positive correlation with their swelling abilities.Acidic PIL with 3-octyl-substituent and 2.5 mol%DVB(PIL-C8-2.5DVB-HSO4)had the highest swelling ability in formic acid and exhibited comparable catalytic activities with homogeneous catalysts such as sulfuric acid and p-toluenesulfonic acid.

Honeycomb-structured solid acid catalysts fabricated via the swelling-induced self-assembly of acidic poly(ionic liquid)s for highly efficient hydrolysis reactions

The development of heterogeneous acid catalysts with higher activity than homogeneous acid catalysts is critical and still challenging.In this study,acidic poly(ionic liquid)s with swelling ability(SAPILs)were designed and synthesized via the free radical copolymerization of ionic liquid monomers,sodium p-styrenesulfonate,and crosslinkers,followed by acidification.The 31P nuclear magnetic resonance chemical shifts of adsorbed trimethylphosphine oxide indicated that the synthesized SAPILs presented moderate and single acid strength.The thermogravimetric analysis results in the temperature range of 300–345°C revealed that the synthesized SAPILs were more stable than the commercial resin Amberlite IR-120(H)(245°C).Cryogenic scanning electron microscopy testing demonstrated that SAPILs presented unique three-dimensional(3D)honeycomb structure in water,which was ascribed to the swelling-induced self-assembly of the molecules.Moreover,we used SAPILs with micron-sized honeycomb structure in water as catalysts for the hydrolysis of cyclohexyl acetate to cyclohexanol,and determined that their catalytic activity was much higher than that of homogeneous acid catalysts.The equilibrium concentrations of all reaction components inside and outside the synthesized SAPILs were quantitatively analyzed using a series of simulated reaction mixtures.Depending on the reaction mixture,the concentration of cyclohexyl acetate inside SAPIL-1 was 7.5–23.3 times higher than that outside of it,which suggested the high enrichment ability of SAPILs for cyclohexyl acetate.The excellent catalytic performance of SAPILs was attributed to their 3D honeycomb structure in water and high enrichment ability for cyclohexyl acetate,which opened up new avenues for designing highly efficient heterogeneous acid catalysts that could eventually replace conventional homogeneous acid catalysts.

The Effects on the Cutting Propagation of Cinnamomum micranthum in Different Seasons

Cinnamomum micranthum is one of China Third-class Endangered Tree Species. The seedlings of C. micranthum are difficult to obtain. It is important to study the cutting propagation of C. micranthum in different seasons to improve the rooting rate for providing seedling propagation technique for the afforestation industry. In this study,the optimal season for the cutting propagation of C. micranthum was summer( May),providing 80. 6% rooting rate. The rooting rate in Summer was 33. 4% higher than that in Spring( March). This technique is important to make the best use of rare C. micranthum resources and to provide plenty of seedlings for afforestation and greening industry.

Improvement of the tissue culture technique for Melaleuca alternifolia

Tea tree oil is extracted from the leaves and twigs of Melaleuca alternifolia （Maiden ＆ Betche） Cheel, and it is widely used in medicines, food preservatives, cosmetics and health care products. Traditional propagation of M. alternifolia from seeds does not necessarily transfer the desired characteristics from their mother trees, the seedlings are not uniform, and the multiplication rate from cuttings is relatively low. For these reasons, it is necessary to develop tissue culture techniques for this species. This study showed that an efficient explant initiation medium for M. alternifolia was MS 1/2 ＋ BA 0.6mg L^-1 ＋NAA 0.1 mg L^-1＋sucrose 30g L-l, which yielded a 75.9 % initiation rate. An efficient multi- plication medium was MS ＋ BA 0.3 mg L^-1＋ NAA 0.15 mg L^-1 ＋ sucrose 30 g L^-1, which yielded a 4.3 multiplication rate and 3.2 cm shoot length. The rooting medium was MS 1/2 ＋ IBA 0.1-0.25 mg L^-1 ＋ sucrose 15 g L^-1, which yielded a 100 % rooting rate, 2.94-3.32 roots per individual and 1.36-1.44 cm root length. Local red-core soil was suitable as a transplant medium, and yielded 98 % survival. This study improved the tissue culture technique for mass-propagation of M. alternifolia, enabling the production of high quality plants for market.

In Vitro Propagation of Ardisia mamillata Hance

Ardisia mamillata Hance is a rare plant with highly ornamental and medicinal value. The traditional propagation methods for A. mamillata by seeds or cutting provided low proliferation rate. This study is to optimize the propagation technique of A. mamillata by tissue culture and set up an industrial production system to provide plenty of A. mamillata seedlings for the human demand. The optimal initiation medium for A. mamillata is MS +2.0 mg/L BA +0.1 mg/L NAA +30 g/L sugar, providing76.4% initiation rate. The optimal shoot proliferation medium for A. mamillata is MS+1.0 mg/L BA+0.1 mg/L NAA+30 g/L sugar, providing 4.56 fold proliferation rate and3.10 cm shoot in height. The optimal shoot elongation medium for A. mamillata is MS+0.5 mg/L BA+0.1 mg/L NAA+30 g/L sugar, providing 2.77 fold proliferation rate and 4.27 cm shoot in height. The optimal rooting medium for A. mamillata is 1/2MS+0.1 mg/L IBA +15 g/L sugar, providing 99.7% rooting rate, 4.0 roots per individual,7.53 cm root in length and 3.94 cm shoot in height. This provides a reliable mass propagation method for A. mamillata.

Efficient synthesis of dimethyl carbonate via transesterification of ethylene carbonate catalyzed by swelling poly(ionic liquid)s

The synthesis of dimethyl carbonate(DMC)via transesterification of ethylene carbonate(EC)and methanol(MeOH)was an environmental and practical strategy.Herein,poly(ionic liquid)s(PILs)with swelling abilities were synthesized by free radical copolymerization of N-vinylimidazolium ionic liquids,sodium 4-vinylbenzoate and cross-linker(1,8-triethylene glycoldiyl-3,3'-divinylimidazolium bromide([(EG)_(3)-DVIm]Br_(2)).The swelling abilities of PILs in various solvents were measured,and PILs could swell in methanol(MeOH).The swelling ability of PILs in MeOH could be modulated by changing the cross-linker content and chain length of 3-alkyl-substituents on imidazolium.The swollen state of PILs in MeOH presented a porous cross-linked network structure observed by the cryo-scanning electron microscope(cryo-SEM).The swelling PILs were used to catalyze the transesterification of ethylene carbonate(EC)and MeOH to prepare the DMC,and the catalytic activities was correlated with the swelling abilities of PILs.The PIL with 3-butyl-substituent and 2.5 mol%cross-linker(poly[VBIm-VBA-DVIm]-2.5%)had the highest swelling ratio(Q=12.4(g/g))in MeOH and EC mixed solvents and exhibited excellent catalytic activities,which was similar to corresponding homogeneous ionic liquid.Furthermore,the catalyst could be reused up to seven runs without any considerable loss of its initial activity.