Aluminum(Ⅲ) triflate-catalyzed selective oxidation of glycerol to formic acid with hydrogen peroxide

Glycerol is a by-product of biodiesel production and is an important readily available platform chemical.Valorization of glycerol into value-added chemicals has gained immense attention.Herein,we carried out the conversion of glycerol to formic acid and glycolic acid using H2O2 as an oxidant and metal(Ⅲ)triflate-based catalytic systems.Aluminum(Ⅲ)triflate was found to be the most efficient catalyst for the selective oxidation of glycerol to formic acid.A correlation between the catalytic activity of the metal cations and their hydrolysis constants(Kh)and water exchange rate constants was observed.At 70 ℃,a formic acid yield of up to 72% could be attained within 12 h.The catalyst could be recycled at least five times with a high conversion rate,and hence can also be used for the selective oxidation of other biomass platform molecules.Reaction kinetics and 1H NMR studies showed that the oxidation of glycerol(to formic acid)involved glycerol hydrolysis pathways with glyceric acid and glycolic acid as the main intermediate products.Both the [Al(OH)x]^n+ Lewis acid species and CF3SO3H Brosted acid,which were generated by the in-situ hydrolysis of Al(OTf)3,were responsible for glycerol conversion.The easy availability,high efficiency,and good recyclability of Al(OTf)3 render it suitable for the selective oxidation of glycerol to high value-added products.

A Study of the Artificial Vegetation Restoration Technology in the Wenchuan Earthquake Area

The situation of plants on the slope can reflect the effect of vegetation restoration during the process of artificial vegetation recovery.Taking the typical damaged slope of Wenchuan earthquake area as the research object,through observing the vegetation situation of deserted slope,the results show that compositae plants and gramineous plants are suitable for being pioneer plants and dominant in community; during the vegetation succession,many compositae and gramineous species invade,but there is no magaphanerophytes invading; as time goes by,the herbaceous species and diversity increase gradually,so the ecosystem becomes more stable and the gradient is important for the vegetation restoration.

极小种群野生植物梓叶槭的种实表型变异特征

表型变异是植物遗传变异与环境异质性相互作用的结果,是植物适应和进化的具体表现。为揭示极小种群植物梓叶槭(Acer catalpifolium)的种实表型在其适应环境过程中的变异特征,明确梓叶槭优质种源地,为该物种的保护提供基础数据,本研究以天然分布的5个小种群的11个种实性状为研究对象,采用巢式方差、变异系数、表型分化系数等多种指标,探讨了其种群间和种群内的表型变异。结果表明:梓叶槭种实表型性状在种群间和种群内均存在着显著的差异,种群内的变异(63.11%)大于种群间的变异(23.61%),种群间平均分化系数为27.23%,分化程度在槭树科植物中相对较大。种子厚度的平均变异系数最高(40.64%),其次是果柄长。翅果千粒重的平均变异系数最小(1.57%),是最稳定的种实性状。都江堰种群的表型多样性最丰富,平武种群的则最低;气象因子对梓叶槭种实表型性状的影响不显著。就种实表型性状而言,虽然雷波种群的翅果最大,平武种群的种子最大,同时两者均具有最大的种子厚度和质量均一度。故平武和雷波种群均可作为梓叶槭优质种质资源的候选地。

不同郁闭度对野外回归的梓叶槭幼树形态和生理特征的影响

濒危植物野外回归是扩大极小种群野生植物种群的有效途径。适宜的回归生境是物种生长的必要条件,研究植物的生理生态特征对不同野外回归生境的适应性,是科学评价濒危物种种群回归生境适宜性的关键指标。本文以野外回归的极小种群野生植物梓叶槭(Acer catalpifolium)为研究对象,探讨了无遮荫、林缘、林隙以及林下(郁闭度由小到大)4种不同光照条件对梓叶槭幼树的形态特征、光合特征、类黄酮指数及叶绿素含量等的影响。结果表明:(1)随着郁闭度的增大,梓叶槭幼树的基径、冠幅以及新生枝条数量产生差异,均呈现先增大后减小的趋势;(2)在林缘生境中,梓叶槭幼树的单叶面积及单叶质量均最大,比叶面积随着郁闭度的增大而增大;(3)随着郁闭度的增大,梓叶槭叶片胞间CO2浓度、蒸腾速率及气孔导度均呈现先减小后增大的趋势,叶绿素含量呈现上升趋势,类黄酮指数则呈现先增大后减小的趋势。综上可知,林缘适宜的光照条件更适合梓叶槭野外回归。这一结果可为梓叶槭以及其他极小种群野生植物的回归生境适宜性的探索研究提供借鉴。