对二甲苯氧化产物的高效液相色谱分析

对甲基苯甲酸是重要的化工原料与药物合成中间体。以过渡金属络合物催化剂氧化对二甲苯合成对甲基苯甲酸,粗产品或精制产品中均或多或少地含有深度氧化副产物对苯二甲酸与对羧基苯甲醛等。分析测定这些副产物对控制氧化反应条件与优化粗产品的精制过程、提高目标产物选     

扁桃酸在玻碳电极上的电化学行为研究

扁桃酸(mandelicacid)具有较强的抑菌作用,可用于治疗泌尿系统疾病,同时也是合成许多抗生素药物的中间体.因此,它在医药合成中具有广泛的用途.对扁桃酸的测定,已有紫外、HPLC、气相色谱、毛细管电泳等方法报道;电化学法测定还未见报道.本文采用现代电化学分析方法系统研究了扁桃酸在玻碳电极上的电化学行为.实验表明扁桃酸在玻碳电极上的氧化是不可逆过程,在pH 2.0介质中,在玻碳电极上都有一定的吸附性.实验研究了在pH 2.0条件下扁桃酸的各种电化学性质,并分别寻找到在不同条件下的定量方法,对实际样品进行了测定,方法简便、快速.     

气相色谱法测定甲苯氧化产物中的苯甲醛及苯甲酸

气相色谱法测定甲苯氧化产物中的苯甲醛及苯甲酸刘敬兰,周鸿娟（河北师范大学实验中心石家庄０５００１６）陈连文傅德才（河北经贸学院石家庄０５００６１）（河北轻化工学院石家庄０５００１８）１前言在由电化学间接氧化法从甲苯生产苯甲醛的反应过程中,反应条件及终点的控制直接影响着苯甲醛的回收率。苯甲醛及苯甲酸的测定方法虽已有报道〔１〕,但同时测定甲苯中两组分含量的方法尚未见报道。２实验部分（１）色谱条件：岛津气相色谱仪ＧＣ－１６Ａ,带Ｃ－Ｒ３Ａ数据处理机。     

高效液相色谱法测定丁香酸及其杂质含量

研究了一种同时测定合成粗产品中丁香酸及其３,４－二羟基－５－甲氧基苯甲酸、３,４,５－三羟基苯甲酸以及３,４,５－三甲氧基苯甲酸含量的高效液相色谱法。用ＯＤＳ－３色谱柱,流动相为甲醇／水／３６％乙酸（４０：６０：２,Ｖ／Ｖ／Ｖ）,检测波长范围为２５０～３００ｎｍ,在选定的色谱条件下,各组份１５ｍｉｎ内实现基线分离。丁香酸、３,４－二羟基－５－甲氧基苯甲酸、３,４,５－三羟基苯甲酸以及３,４,５－三     

紫外分光光度法测定肉桂醛、苯甲醛和苯甲酸

根据肉桂醛、苯甲醛和苯甲酸的紫外吸收光谱特征及肉桂醛和苯甲醛在228 nm和256 nm波长处有两个等吸收点,提出了测定三组分的紫外分光光度法.选择228 nm,256 nm及311 nm 3个波长作为测定波长,建立了联立方程组,求得了组分浓度与吸光度之间的关系:C内桂醛=(A311 nm-0.008 4)/0.042 4;C笨甲醛=(A256 nm-0.000 5)/0.062 2-C内桂醛;C苯甲酸=(A228 nm+0.005 7)/0.061 1-C内桂醛-C苯甲醛.相应的线性范围依次在18.03,13.08,9.233 mg·L-1以内.对方法的重现性作了试验,上述3种化合物的相对标准偏差(n=6)均小于1%.用标准加入法进行回收试验,测得其平均回收率在99.1%～100.5%之间.     

2,6-二-O-戊基-β-环糊精涂渍Symmetry C8柱拆分扁桃酸及其类似物对映体

利用合成的2,6-二-O-戊基-β-环糊精涂渍Symmetry C8色谱柱,研究了扁桃酸及其类似物等6 种外消旋对映体的反相高效液相色谱拆分。优化了色谱分离条件,探讨了扁桃酸的手性拆分机理。结果表明,采用优化后的甲醇-水或甲醇-0.5%三乙胺-乙酸缓冲液流动相等色谱条件,扁桃酸、扁桃酸甲酯、苯基甘氨酸、苯基琥珀酸和安息香等5种外消旋对映体达到或接近基线分离,其中前4种对映体均为(S)-构型先出峰。该法可用于实际样品的对映体纯度测定。     

3-芳基苯并呋喃酮类化合物的合成及抗肿瘤活性

以甲氧基取代苯甲醛和氯仿为起始物, 以四丁基溴化铵(TBAB)为催化剂, 在氢氧化钠溶液中反应制得甲氧基取代扁桃酸钠, 经酸化得到相应的甲氧基取代扁桃酸; 在三氟化硼-乙醚催化下, 甲氧基取代扁桃酸分别与不同的酚类化合物发生串联的酯化-分子内环合反应, 便捷、 高效地合成了13种3-芳基苯并呋喃酮类化合物. 采用噻唑蓝(MTT)法对其中11种化合物进行了肿瘤细胞增殖抑制活性研究, 结果表明化合物4a, 4j及4a, 4i具有较强的抗肿瘤活性.     

比值导数光谱与多波长最小二乘回归分光光度法同时测定苯甲酸、苯甲醛和苯甲醇

提出了比值导数光谱多波长最小二乘回归分光光度法测定苯甲酸、苯甲醛和苯甲醇三组分混合物。合成试样４ 次平行测定的相对标准偏差为０ ．１６ ％ ～４．３５ ％ 。回收率在９１ ．４３ ％ ～１０５．９ ％ 之间。     

比值导数光谱与多波长最小二乘回归分光光度法同时测定？…

提出了比值导数光谱－多波长最小二乘回归分光光度法测定苯甲酸、苯甲醛和苯甲醇三组分混合物。合成试样４次平行测定的相对标准偏差为０．１６％～４．３５％。回收率在９１．４３％～１０５．９％之间。     

气相色谱法测定医用苯甲酸软膏中的苯甲酸与水杨酸含量

复方苯甲酸水杨酸制剂或软膏被广泛用作外用杀菌或消毒药.近年报导的测定方法主要有薄层法[1],卡尔曼滤波分光光度法[2]与气相色谱分析法[3].用气相色谱法测定苯甲酸或水杨酸等芳香酸或取代芳香酸,多将这些酸先经各种衍生反应转变为相应的酯再进行气相色谱测定[4,5].所采用的酯化衍生反应有些较为繁琐,有些反应不够完全或引入了某些衍生试剂,给分离系统或GC分离带来一些不利影响.本文提出了一种新的丁酯衍生化前处理法.用本法测定医用苯甲酸软膏中的苯甲酸与水杨酸含量,先以75%的热乙醇溶液充分溶解软膏基质,之后用冰水骤冷使基质从乙醇溶液中析出,然后将溶液中的待测酸转变为相应丁酯并选择102硅烷化白色载体涂渍5%的SE-30填充柱对各酸丁酯进行GC分离.本法定量准确,操作也较简便.     

有机化学反应中海水替代淡水试验的初步探讨

分别使用淡水和海水进行了乙酰苯胺和扁桃酸的制备、康尼查罗反应和霍夫曼重排等5个反应研究。结果表明,某些反应可以直接用海水替代淡水进行,如邻氨基苯甲酸的制备,产率为77.2%,与应用淡水的文献值接近;某些反应可由海水经简单处理后替代淡水进行,如苯甲醛的康尼查罗反应,产率为52.2%,与应用淡水的文献值接近;而2-氯-3-氨基-4-甲基吡啶的制备实验,产率为98.1%,优于应用淡水的文献值;而乙酰苯胺和扁桃酸的制备使用海水或经简单处理后的海水的实验结果均不理想。     

Preparation of chitosan‐based molecularly imprinted material for enantioseparation of racemic mandelic acid in aqueous medium by solid phase extraction

An S‐mandelic acid imprinted chitosan resin was synthesized by cross‐linking chitosan with glutaraldehyde in 2% acetic acid solution. S‐Mandelic acid imprinted chitosan resin was used to enantioselectively separate racemic mandelic acid in aqueous medium. When keeping the pH of sample solution (100 mM Tris‐H₃PO₄) at 3.5 and adsorption time at 40 min, the enantiomer excess of mandelic acid in supernatant was 78.8%. The adsorption capacities of S‐mandelic acid imprinted chitosan resin for S‐ and R‐mandelic acid were determined to be 29.5 and 2.03 mg/g, respectively. While the adsorption capacities of non‐imprinted cross‐linked chitosan for S‐ and R‐mandelic acid were 2.10 and 2.08 mg/g, respectively. The result suggests that the imprinted caves in S‐mandelic acid imprinted chitosan resin are highly matched with S‐mandelic acid molecule in space structure and spatial arrangement of action sites. Interestingly, the enantiomer excess value of mandelic acid in supernatant after adsorption of racemic mandelic acid by R‐mandelic acid imprinted cross‐linked chitosan was 25.4%. The higher enantiomer excess value by S‐mandelic acid imprinted chitosan resin suggests that the chiral carbons in chitosan and the imprinted caves in S‐mandelic acid imprinted chitosan resin combine to play roles for the enantioselectivity of S‐mandelic acid imprinted chitosan resin toward S‐mandelic acid. Furthermore, the excellent enantioselectivity of S‐mandelic acid imprinted chitosan resin toward S‐mandelic acid demonstrates that using chiral chitosan as functional monomer to prepare molecularly imprinted polymers has great potential in enantioseparation of chiral pharmaceuticals.     

Nucleophilic benzoylation using a mandelic acid dioxolanone as a synthetic equivalent of the benzoyl carbanion. Oxidative decarboxylation of alpha-hydroxyacids

The synthesis of alkyl aryl ketones using a mandelic acid dioxolanone as a synthetic equivalent (Umpolung) of the benzoyl carbanion is reported. The methodology involves alkylation of the mandelic acid dioxolanone, hydrolysis of the dioxolanone moiety in the alkylated products and oxidative decarboxylation of the resulting alpha-hydroxyacids. The last step is carried out in a catalytic aerobic way using a Co (III) complex in the presence of pivalaldehyde under very mild conditions.     

L-亮氨酸衍生物手性氨基醇的合成与应用

以N,N-二甲基苯胺为原料,经对位溴化、邻位甲酰化得到5-溴-2-(二甲氨基)苯甲醛;L-亮氨酸经酯化、格氏反应得到二齿手性氨基醇;将5-溴-2-(二甲氨基)苯甲醛与上述氨基醇经缩合、还原得到三齿手性氨基醇;产物经红外光谱(IR)、质谱(MS)及核磁共振氢谱(1H-NMR)表征,考察了二齿手性氨基醇和三齿手性氨基醇作为...     

The dimethyldioxirane-mediated oxidation of phenylethyne

The product pattern found for the dimethyldioxirane-mediated oxidation of phenylethyne strongly depends on the reaction conditions. Dimethyldioxirane generated in situ from caroate (HSO(5)(-)) and acetone in acetonitrile-water furnishes phenylacetic acid as the main product. With solutions of dimethyldioxirane in acetone, mandelic acid and phenylacetic acid are mainly formed. The relative abundances of the two acids depend on the residual water present in the dimethyldioxirane-acetone solution. Application of thoroughly dried solutions of the reagent effects increased formation of mandelic acid. When phenylethyne is oxidized by dimethyldioxirane transferred into tetrachloromethane, to minimize traces of water even further, oligomeric mandelic acid is obtained. The results are rationalized by the initial formation of phenyloxirene, which is known to equilibrate with phenylformylcarbene and benzoylcarbene. Subsequent Wolff rearrangement produces intermediate phenylketene, which can be trapped by water as phenylacetic acid or suffer from further oxidation to the alpha-lactone of mandelic acid. The alpha-lactone can either react with water to yield mandelic acid or, under anhydrous conditions, to yield oligomeric mandelic acid. In addition to mandelic acid and phenylacetic acid phenylglyoxylic acid, benzoic acid and benzaldehyde are observed as reaction products. The formation of phenylglyoxylic acid by transfer of two oxygen atoms to the unrearranged carbon skeleton of phenylethyne followed by oxygen insertion into the aldehydic C-H bond of the intermediately formed phenylglyoxal is discussed. In a second pathway this acid is formed by partial oxidation of mandelic acid. Benzaldehyde and benzoic acid are explained as products of the oxidative degradation of the alpha-lactone by dimethyldioxirane. Under in situ conditions benzoic acid is also formed by caroate initiated oxidative decarboxylation of phenylglyoxylic acid and/or intermediate phenylglyoxal.     

D/L扁桃酸的合成研究

对D／L扁桃酸的合成工艺进行了优化,尤其在溶剂的选择与回收,二氯化物的制备以及产品的纯化与提取等方面作了有效的改进,收率与纯度有很大改善,分别达到80％和99．4％。     

Chiralpak AD-H和Chiralcel OJ-H手性固定相拆分扁桃酸系列化合物

对比了商品化的淀粉型手性固定相Chiralcel OJ-H和纤维素型手性固定相Chiralpak AD-H柱在正相条件下对扁桃酸系列8个化合物的拆分,结果表明Chiralcel OJ-H柱对扁桃酸系列化合物具有更强的手性识别能力,8个外消旋扁桃酸化合物在36 min内都得到了基线分离。研究发现,扁桃酸苯环上的取代基对其拆分的难易程度影响很大,其电子诱导效应影响扁桃酸类化合物在固定相上的保留时间,其空间位阻效应是扁桃酸在固定相上被拆分成败的决定因素。通过对比分析扁桃酸和手性柱的结构,探讨了可能的手性拆分机理是基于Chiralpak AD-H(Chiralcel OJ-H)手性固定相和扁桃酸系列化合物之间的氢键-氢键、偶极-偶极、π-π电子相互作用以及空间适应性等诸多因素的综合影响,其中空间适应性起到至关重要的作用。本研究可为一些实际光学活性扁桃酸及其类似物的对映体纯度测定与拆分研究提供参考。     

Kinetic Resolution of Racemic Mandelic Acid Esters by N,N′‐Dioxide–Scandium‐Complex‐Catalyzed Enantiomer‐Selective Acylation

A simple and efficient acylative kinetic resolution of racemic mandelic acid esters was accomplished with a chiral N,N’‐dioxide–scandium(III) complex under mild and base‐free reaction conditions. A variety of mandelic acid esters performed well in the reaction, obtaining both acylated products (up to 49% yield, 97% ee) and recovered substrates (up to 49% yield, 95% ee) in high enantioselectivities with perfect selectivity factors (up to 247). The enantioselective recognition and catalytic models were also proposed for the catalytic KR reaction.     

Expeditious Synthesis of Ramipril: An Angiotensin Converting Enzyme (ACE) Inhibitor

We document an efficient and cost‐effective synthesis of ramipril 1 utilizing (i) an environmentally benign process for the esterification of racemic 2‐aza‐bicyclo‐[3.3.0]‐octane‐3‐carboxylic acid hydrochloride 2 using boric acid as a catalyst and (ii) a robust resolution process for the synthesis of 3a by means of inexpensive and recyclable L‐(+)‐mandelic acid as key steps.     

Structural Characterization and Degradability of Poly(L‐lactic acid)s Incorporating Phenyl‐Substituted α‐Hydroxy Acids as Comonomers

Three types of copolymers of poly(L ‐lactic acid) (PLLA) were synthesized by direct polycondensation of L ‐lactic acid and phenyl‐substituted α‐hydroxy acids (L ‐phenyllactic acid and D ‐ and L ‐mandelic acids). It was found that the glass transition temperature of the copolymers comprising L ‐mandelic acid became significantly higher (from 58 to 69 °C) with increasing content of L ‐mandelic acid (from 0 to 50 mol‐%) although the M _w decreased (from 87 000 to 4 000 Da). The cast films of the L ‐mandelic acid containing copolymers showed improved tensile properties compared with those of the PLLA film. This may be due to a pinning effect of the L ‐mandelic acid units on the helix formation of PLLA, although 30% of the units were racemized. The enzymatic degradability of the L ‐mandelic acid containing copolymers was much higher than that of PLLA, as analyzed with Proteinase K® originating from Tritirachium album.

Synthesis of copolymers of L ‐lactic acid and phenyl‐substituted α‐hydroxy acids.