荧光分光光度法测定小诺霉素

小诺霉素具有微弱荧光,被高碘酸钠在沸水中氧化后水解形成醛基,可与乙酰丙酮及氨基在一定条件下生成一种具有强荧光的衍生物。此衍生物在常温下可稳定40 min以上,其荧光强度较小诺霉素显著增强,且最大激发波长和发射波长分别红移33 nm和68 nm。在1.0×10-8~1.0×10-7mol/L浓度范围内,小诺霉素的荧光强度与其浓度呈良好的线性关系,相关系数r为0.9925。方法用于实际样品的测定,结果较为满意。     

A study of the physico-chemical properties of 1,3,5-trihydroxy-1,3,5-triazin-2,4,6[1H,3H,5H]-trione

Acetyl (Ia) and pivaloyl (Ib) triesters of the 1N,3N,5N-trihydroxy-1,3,5-triazin-2,4,6[1H,3H,5H]-trione (I) were synthesised. The spectrophotometric and potentiometric investigation of I revealed a weak acidic properties of triprotonic acid (pK_a1=5.23, pK_a2=6.32, and pK_a3=7.93). The MS and TGA analyses of I indicated on hydroxyisocyanate as possible degradation product. The chelating ability of I with Fe(III)-ion was preliminary explored. IR measurements of aqueous solutions of I in the presence of Fe(III) ion showed the possible chelating ability of all hydroxamic moieties. The chemical structures and properties of investigated compounds were derived from the results of IR, ¹H and ¹³C NMR, UV and MS spectrometric data, as well as thermogravimetric and potentiometric analysis.     

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.     

Alternate π-Bond Routes for Carbon-13-Carbon-13 Spin-Spin Coupling - Hyperconjugative σ-π vs Non-Classical p-p Interactions

In a previous report¹ longer-range carbon-13-carbon-13 spin-spin coupling up to five bonds was noted in ¹³C-carboxyl-9,10-dihydro-9-anthroic acid. Although many types of longer-range proton-proton couplings in various π-systems are known² (e.g., cumulenes) which may portend analogous π-systems in carbon-carbon couplings, this type of carbon-carbon coupling observed in 9,10-dihydro-9-anthroic acid has no analogy in proton-proton coupling, since proton cannot be incorporated within a ring.     

A facile method for regioselective synthesis of new N-acetyl/thioacetyl-(E)-stilbene benzenesulfonamide derivatives via N-acetyl/thioacetyl sulfonamide formation

A series of new N-acetyl/thioacetyl-(E)-stilbene benzenesulfonamide derivatives were synthesized regioselectively in moderate to high yields by following a convenient, three-step procedure. The procedure consists of the direct oxidative conversion of a thiol compound to the corresponding sulfonyl chloride using TMSCl/KNO₃, followed by a room temperature reaction in a one-pot transformation of the resultant sulfonyl chloride into N-acetyl/thioacetyl sulfonamide, which undergoes a further Pd-catalyzed coupling reaction, giving rise to the stilbene compounds reported for the first time.     

乙酰柠檬酸丁酯增韧竹粉/聚乳酸生物质复合材料的制备与性能

以竹粉(bamboo flour,BF)为生物质填料,乙酰柠檬酸丁酯(acetyl tributyl citrate,ATBC)为增韧剂,通过与聚乳酸(polylactic acid,PLA)熔融共混制备了BF/PLA增韧复合材料,并采用红外光谱、热重分析、转矩流变仪、扫描电镜及力学性能测试等考察了ATBC添加对BF/PLA复合材料结构与性能的影响。结果表明,ATBC可改善BF/PLA复合材料的加工流变性,降低复合材料玻璃化转变温度、冷结晶温度及熔融温度,但对复合材料的热稳定性没有影响。FTIR分析显示,ATBC的加入可使BF/PLA复合材料C—O红外吸收峰位增大,表明ATBC与PLA之间存在一定相互作用。当ATBC用量为15%时,BF/PLA复合材料断裂伸长率由增韧前的8.1%增加到35.6%,提高了339.5%。SEM图片显示,此时复合材料断面粗糙,表现出韧性断裂形貌。该研究结果可为进一步探索增韧竹纤维/聚乳酸复合材料制备及应用,提供试验数据和理论参考。     

Synthesis of Some New 3-Oxo-2-[(Z)-1-phenylmethylidene]-5H-[1,3]thiazolo[3,2-a]-and N-Acetylated Pyrimidines

3-Oxo-2-[(Z)-1-phenylmethylidene]-5H-[1,3]thiazolo[3,2-a] pyrimidine derivatives 2a–f were synthesized by the reaction of an appropriate 3,4-dihydro-2(H)-pyrimidone 1 , chloroacetic acid, sodium acetate and benzaldehyde. Reaction of 1 with acetic anhydride under heating afforded only 3-N-acetylated 3,4-dihydro-2(H)-pyrimidines 3a–f . The yields of the products after recrystallization from ethanol were of the order of 60–92 %. IR, ¹ H NMR spectroscopy, and elemental analysis were used for the identification of these compounds.     

Copper-catalyzed synthesis of aromatic carboxylic acids from arylboronic acids and acetyl acetate

A simple and efficient copper-catalyzed method for the synthesis of aromatic carboxylic acids in moderate to high yields with great functional-group compatibility in the substrates has been developed. The new method uses readily available arylboronic acids and acetyl acetate as the starting materials and inexpensive CuI as the catalyst.     

Gas chromatographic study of acetyl derivates of chlorinated guaiacols

Summary The gas chromatography of acetyl derivatives of guaiacol and all chlorinated guaiacols has been studied on SE-30, OV-351 and Carbowax 20M capillary columns. The retention order and relative retention times under isotermal and temperature-programmed conditions are discussed. Different retention times for all mono- and dichloro compounds have been observed on the SE-30 column. However, all trichloroguaiacol isomers were separated only on polar columns. The best overall temperature-programmed separations have been achieved on an SE-30 capillary column.