Facile Synthesis of Rhodamine Esters using Acetyl Chloride in Alcohol Solution

The rhodamines are a highly fluorescent class of compound used in many different fields of research, from the lasing medium in dye lasers to biological stains and markers for cellular drug resistance. In this study, esters (2–7) of rhodamine 110 (1) were conveniently prepared via the addition of acetyl chloride to a solution of the free acid (1) in the appropriate alcohol. This method conferred several advantages over previous preparations, namely that for low boiling alcohols, simple evaporation of the solution afforded the ester in quantitative yield with no need for purification. For higher boiling point alcohols, a method has been developed which allows the separation of longer chain esters from the alcohol solvent.     

A Convenient Synthesis of Thioacetates and Thiobenzoates Using Silica-Gel Supported Potassium Thioacetate

Abstract

A simple and efficient procedure has been developed for the synthesis of thioesters by a reaction of alkyl halides with silica-gel supported potassium thioacetate or thiobenzoate under mild conditions.     

FeCl3.6H2O作用的a-羰基-a-乙酰/羧基二硫缩烯酮的脱乙酰/羧基反应

探讨了价廉易得、环境友好和无毒性的FeCl3.6H2O作用的a-羰基-a-乙酰/羧基二硫缩烯酮的脱乙酰/羧基反应,高产率合成a-羰基二硫缩烯酮。该反应具有反应条件温和、环境友好和操作简单等优点。     

A Highly Regioselective Deacetylation of Taxanes

A highly regioselective O-deacetylation of taxanes at C-5 position was accomplished by treatment with t-BuOK and a possible mechanism was proposed.     

二丁基氧化锡在糖苷类化合物脱乙酰保护基中的应用

发展了在中性条件下选择性脱乙酰保护基的新方法。该方法以催化剂量的二丁 基氧化锡作催化剂，用甲醇作溶剂，对糖苷类化合物脱乙酰保护基进行了研究。文 中对该反应结果、应用范围与反应机理进行了讨论，本研究表明糖苷类化合物采用 该方法可以顺利得到脱乙酰保护基产物，所得到产物的结构经~1H NMR，IR，元素 分析证实。脱保护基的反应在有机合成中具有很重要的意义，该方法属于首次将二 丁基氧化锡用于脱乙酰保护基的反应中。     

二丁基氧化锡脱脂肪族糖苷乙酰保护基的研究

研究了以二丁基氧化锡为催化剂, 在甲醇溶剂中, 含有不同官能团的脂肪族糖苷的脱乙酰保护基反应. 结果表明采用该方法可以选择地得到糖上全部或部分脱乙酰保护基产物, 并且脱保护产物的立体构型保持, 没有分解现象发生. 该方法具有操作简单、反应条件温和、产率高等特点.     

酸碱电导滴定法测定壳聚糖脱乙酰度

研究了酸碱滴定中壳聚糖溶液电导的变化，利用电导变化两个转折点之间碱的用量来计算壳聚糖的脱乙酰度，消除了壳聚糖吸附的残留酸或碱的影响。该方法具有准确可靠、重复性好、转折点明显等优点。用于实际样品的测定，结果较好，相对标准偏差小于0.6%。     

An Alternative Method for Anomeric Deacetylation of Per-acetylated Carbohydrates

An alternative method for anomeric deacetylation of fully acetylated carbohydrates has been developed using imidazole in methanol.     

紫外光谱法测定甲壳素的脱乙酰化值

用紫外光谱测定甲壳素脱乙酰程度，该法快速简便，重现性好，试样无需特殊处理。     

NMR、FTIR及电位滴定法测定壳聚糖脱乙酰度

脱乙酰度是影响甲壳素、壳聚糖及其衍生物物化特性和生物活性功能的重要参数。介绍了三种壳聚糖脱乙酰度的测定方法。以^13C交叉极化魔角旋转固体核磁法测定的结果作为参照，对红外光谱法和线性电位滴定法的测定结果进行了分析比较，并分析了不同测定方法的误差来源。     

A Novel Method for the Synthesis of Acetyl Phosphate

A facile method for the synthesis of acetyl phosphate by a reaction of 2-hydroxypropylphosphate with acetic acid is described.     

Enhancement of Methanol Tolerance in DMFC Cathode: Addition of Chloride Ions

In the operation of a direct methanol fuel cell, the modification by chloride ions on the surface of a Pt cathode can facilitate the extraordinary increase of power performance and long‐term stability. Analyzing the results of cyclic voltammograms and electrochemical impedance spectroscopy, the positive shift of Pt oxidation onset potential and the depression of oxidation current are observed, which results from the role of chloride as surface inhibitor. In addition, O₂ temperature‐programmed desorption and X‐ray photoelectron spectroscopy also reveal that the suppression of Pt surface oxide can be best understood in terms of lower binding of oxygen species by the alteration of electronic state of Pt atoms. Such a reduced surface oxide formation not only provides more efficient proton adsorption sites with high selectivity but also decreases the mixed potential by crossover methanol, resulting in higher performance and stability even under high voltage long‐term operation.     

不同脱乙酰度对壳聚糖表面物理及吸附性能的影响

壳聚糖是甲壳素部分脱乙酰化的产物,脱乙酰度的大小对壳聚糖的性能影响很大。利用碱液法,通过对反应时间的控制,制备了不同脱乙酰度的壳聚糖并对其性能进行了研究。结果表明,随着脱乙酰度的增大,壳聚糖膜的吸水率增加,而对其表面接触角的变化则没有影响。同时,壳聚糖海绵对Ca2+和牛血清蛋白(BSA)的吸附能力也随着脱乙酰度的增大而增加。     

Mode of action of acetylesterases associated with endoglucanases towards water-soluble and -insoluble cellulose acetates

A screening of commercial enzyme preparations for the capability ofcellulose acetate (CA) deacetylation revealed that such enzyme activity ismore common than could be anticipated. Enzyme-aided deacetylation of celluloseacetate was clearly a function of the degree of substitution (DS). Celluloseacetates up to a DS of 1.4 were deacetylated by a large number of enzyme mixes.Interestingly, none of the investigated enzyme preparations had the capabilityfor complete cellulose acetate deacetylation. Definitely most hydrolasepreparations investigated in our study deacetylated cellulose acetate with nopreference for a certain position, as could be confirmed by NMR spectroscopy.However, one acetyl esterase had a clear preference for the C2- andC3-positions, leaving the acetyl substituents at the C6-position intact.     

Copper Corrosion in Acid Chloride Solutions: A Quartz Microgravimetry Study

Making use of the quartz microgravimetry method allows one to in situ obtain the m vs. t curves simultaneously with the E _cor vs. t curves (m is the weight of a dissolved or deposited substance, t a time period, E _cor a corrosion potential), which gives one a chance to determine the corrosion rate and its dependence on the concentration of copper ions and chloride ions in solution to within a good accuracy. The corrosion rate increases with increasing concentration of ions of divalent copper in solution, while an increase in the concentration of chloride ions does not lead to its change. The formation of a salt film of an intermediate compound of univalent copper during the copper dissolution process in solutions diluted with respect to chloride ions (0.1 M NaCl, 0.03 M CuCl₂) is discovered experimentally. In the m vs. t curves, the formation of the film manifests itself in the form of an increase in the electrode weight, while the corrosion potential transients reflect but weakly the occurring complex surface conversions. Techniques for the identification of intermediate solid species are proposed. The coefficients of mass transfer with respect to ions of divalent copper are determined. Explanations for variations in the system's behavior following a decrease in the concentration of chloride ions in solution are offered.     

乙酰基的电子激发态

对乙酰基的基态（X12A′）和激发态进行了理论和实验研究。通过采用MRSDCI和MP2方法计算，获得了CH3CO自由基的四个电子激发态（A12A″，B22A′，C32A′，D22A″），其垂直激发能分别为250．8kJ·mol－1，472．3kJ·mol－1，645．8kJ·mol－1和674．7kJ·mol－1。运用时间分辨付里叶红外光谱仪（TR－FTIR）分别研究了CH3CO自由基的热解和光解反应，观察到初生产物CO（V）的红外发射光谱．势垒仅为75．2kJ·mol－1的基态CH3CO极易热解．532um的激光只能将CH3CO激发到束缚态A12A″，故未观察到CO信号；而248nm或266nm的激光可使CH3CO发生B22A′←X12A′跃迁，生成高振动激发的CO（V8）产物．     

Copper in Acid Chloride Solutions: Electrochemical Behavior by Quartz Microgravimetry and Voltammetry

The cathodic deposition of copper on a gold electrode and its subsequent anodic dissolution in an acid chloride solution, where two successive stages of a one-electron transfer are distinguishable because of the stability of chloride complexes of Cu(I), is studied by voltammetry and quartz microgravimetry. The formation of a film of an intermediate compound of Cu(I) during the deposition and dissolution of copper is revealed experimentally. Techniques for identifying the intermediate solid species are suggested. During a cathodic polarization, a film of intermediate compound CuCl forms at a reduced concentration of chloride ions in the Cu(II)/Cu(I) process, while during the anodic dissolution of the copper deposit formed during the cathodic polarization the intermediates appear in the Cu(0)/Cu(I) process, the concentration of chloride ions notwithstanding. The change in the electrochemical behavior of the system caused by a decrease in the concentration of chloride ions is explained.     

In vitro Photo‐Oxidation of Pyruvate to Acetyl: A Main Source for the Formation of Acetyl Coenzyme A in the Citric Acid Cycle to Perform Biochemical Reactions

The kinetics of photooxidation of pyruvate was investigated in presence of zinc oxide catalyst under illumination of visible light. The influence of different parameters such as concentrations of reactants, amount of catalyst and irradiation time was studied on the redox reaction under pseudo‐first order conditions. The results indicated that amount of catalyst, presence of electron accepter in solution and irradiation time was the key factors influencing the efficiency of photo‐oxidation of pyruvate to acetyl.     

离子色谱法分析土壤中的矮壮素和缩节胺

建立了离子交换色谱一直接电导法同时测定土壤中矮壮素和缩节胺残留的分析方法。样品经磨碎超声提取后,用固相萃取（SPE）柱祛除蛋白质,过0．22μm过滤膜,进样检测。考察了不同的阳离子色谱柱SH-CC-1,SH-CC-2,SH—CC_3及其不同的淋洗液对矮壮素、缩节胺的保留时间和分离度的影响。确定了最佳色谱条件：SH—CC-3阳离子色谱柱;直接电导检测;淋洗液选用3．0mmol／L甲烷磺酸,流速为1．0mL／min;柱温：40℃;进样量：100μL。在此条件下,矮壮素及缩节胺在0．20-20．0mg／地范围内,线性相关系数,均大于0．999,矮壮素和缩节胺的检出限（S／N=3）分别为0．070,0．073mg／kg,加标回收率分别为86．0％-93．8％,84．9％～93．2％,测定结果的相对标准偏差小于4．2％。方法选择性好,灵敏度高,抗干扰能力强,适用于检测土壤中矮壮素和缩节胺。     

氯化铜催化偶联合成4-烷基联苯

4-烷基联苯是重要的液晶中间体. 以氯化铜为C—C键偶联反应催化剂, 经过对溴联苯的Grignard试剂直接与溴代烷烃发生偶联反应, 成功合成了一系列4-烷基联苯类化合物, 部分化合物产率高达91%左右, 并对其反应条件进行了初步研究; 所合成化合物结构都经过元素分析、红外光谱、核磁共振氢谱和质谱鉴定. 与现有方法相比, 此合成方法收率高、环境友好、成本相对较低.