固体硫酸铁催化合成不饱和5(4H)-噁唑酮反应的研究

首次采用固体硫酸铁作催化剂,用饱和噁唑酮与醛酮反应,合成了10种不饱和噁唑酮.并通过m.p测定,NMR测定,IR测定等,对产物进行了表征.     

食用香料2,4,5-三甲基噁唑和4-乙基-2,5-二甲基噁唑的合成

分别以丙氨酸和2- 氨基丁酸为起始原料,经Dakin-West 和Robinson-Gabriel 两步反应合成2,4,5- 三甲基噁唑和4- 乙基-2,5- 二甲基噁唑两种食用香料。考察催化剂、原料物质的量比、反应温度、反应时间、环化缩合剂种类等因素的影响,确定2,4,5- 三甲基噁唑的较佳合成工艺：第一步Dakin-West 反应,丙氨酸与乙酸酐的物质的量之比1:11,二甲基氨基吡啶和无水乙酸钠作催化剂(二甲基氨基吡啶用量为丙氨酸物质的量的10%、无水乙酸钠用量为丙氨酸物质的量的2.5 倍),130℃反应5h,得产物Ⅰ(α- 乙酰氨基酮);第二步Robinson-Gabriel 反应,以多聚磷酸为环化脱水剂,产物Ⅰ与PPA 物质的量比1:4,150℃反应2h,得产物Ⅱ。产物Ⅱ减压蒸馏纯化得2,4,5- 三甲基噁唑,两步反应的总产率为30.5%。按上述条件合成4- 乙基-2,5- 二甲基噁唑,两步反应的总产率为28.8%。2,4,5- 三甲基噁唑和4- 乙基-2,5- 二甲基噁唑均具有烤香、清香香气特征。产品结构通过质谱、红外光谱和核磁共振进行确认。本合成工艺路线以氨基酸为原料,具有原料易得、操作简单、产品香气纯正的优点,具有较好的工业化开发前景。     

液相色谱-串质谱法测定大米中异噁唑草酮及代谢物残留量

目的建立大米中异噁唑草酮及代谢物残留量的液相色谱-串联质谱法测定方法。方法试样中残留的异噁唑草酮除草剂及代谢物用乙酸乙腈溶液(1:99,V:V)高速匀浆提取,提取液经N-丙基乙二胺(PSA)、十八烷基硅烷(ODS)净化,经色谱柱为ACQUITY UPLC BEH Phenyl分离和流动相为1.5%乙酸的乙酸铵(1mmol/L)-乙腈进行梯度洗脱,用配有大气压化学电离源(APCI)的液相色谱-串联质谱仪检测和确证。结果异噁唑草酮及代谢物在0.0025~1.000μg/m L浓度范围内呈现良好线性关系(r=0.9998~0.9999)。当样品加标浓度在5~200μg/kg范围内时,其样品加标平均回收率为70.2%~110.6%,相对标准偏差为7.38%~12.84%。异噁唑草酮及代谢物的最低检出限分别为10μg/kg、5μg/kg。结论本方法适用于大米中异噁唑草酮及代谢物残留的同时测定。     

烟草中“噁唑菌酮”和“咪唑菌酮”的残留分析

以乙腈作萃取剂,建立了用超高效液相色谱仪快速检测烟叶中“噁唑菌酮”和“咪唑菌酮”残留的方法,并采用该法测定了22个烤烟烟叶样品中的残留量.结果表明:①方法的回收率在90.6％ ～ 107.2％之间,RSD均小于7％,检测限在0.006～0.009 μg·mL-1之间;②所有样品中均未检出“噁唑菌酮”;20样品中检出“咪唑菌酮”,检出率为91％.残留量在0.20～0.56 μg·g-1之间,均低于目前国际上规定的残留限量标准.该法适合批量烟叶样品中这2种农药残留量的快速测定.     

几种醛类鞣剂及其成品革中甲醛含量探析

甲醛通常用作有机合成鞣剂的原材料,由于其对人类及别的生物体的毒性,因此其使用受到限制,通过对THPC,THPS,噁唑烷A和噁唑烷E及成品革的甲醛含量进行测定,考察了这几种无铬鞣剂的使用条件.     

噁唑烷鞣剂在制革工业中的应用研究及展望

噁唑烷是一类可以与皮胶原反应的环状化合物,本文概述了噁唑烷鞣剂的化学性质及研究状况,对噁唑烷作为皮革鞣剂在皮革工业中的应用历史及现状进行了概述,对噁唑烷的改性方法进行了概括,并对其在制革工业中的应用前景进行了展望。     

噁唑烷在制革生产中的应用

噁唑烷被认为是当今最好的无铬鞣剂之一，就国内外对噁唑烷的开发与利用做一详细的介绍与说明，并提出当今对噁唑烷的进一步发展所存在的问题。     

以三聚氯化氰为脱水剂合成饱和5（4H）—恶唑酮反应的研究

从N酰基氨基酸出发，以三聚氯为氰为脱水剂，合成出8种2（取代苯基）5恶唑酮。通过熔点测定，红外光谱测定，核磁测定对产品进行了表征。     

噁唑烷鞣剂的研究概况与展望

主要阐述了噁唑烷鞣剂的种类、合成方法、应用现状以及与皮纤维结合的鞣制机理,并对噁唑烷的发展趋势做了展望。     

以三聚氯化氰为脱水剂合成饱和5(4H)-嗯唑酮反应的研究

从N酰基氨基酸出发,以三聚氯化氰为脱水剂,合成出8种2(取代苯基)5 唑酮.通过熔点测定、红外光谱测定、核磁测定对产品进行了表征.     

Candida etchellsii产2(5)-乙基-4-羟基-5(2)-甲基-3(2H)-呋喃酮的影响因素

在埃切假丝酵母(Candida etchellsii)发酵过程中,通过盐度调控和氨基酸添加,强化目标产物HEMF(2(5)-乙基-4-羟基-5(2)-甲基-3(2H)-呋喃酮)的合成效率。分阶段调控发酵体系的盐度(初始阶段控制CaCl浓度为200 g/L,发酵40 h后提升至220 g/L),结合氨基酸添加(向发酵体系中添加丙氨酸、精氨酸和甘氨酸各1.67 g/L)。摇瓶结果表明:酵母C.etchellsii合成HEMF,其产量为110.74 mg/L。7 L发酵罐上罐验证,HEMF产量达到121.51 mg/L,相比空白(200 g/L CaCl浓度下且没有添加氨基酸)提高了21.2倍。分阶段盐度调控结合氨基酸添加策略显著强化了C.etchellsii对HEMF的合成。     

3-苯基-4-氨基-5-硫酮-1,2,4-三唑对牛蒡中酪氨酸酶的抑制作用

以3-苯基-4-氨基-5-硫酮-1,2,4-三唑(APTT)为效应物,通过SPSS设计正交试验,研究不同APTT浓度、时间以及温度对牛蒡酪氨酸酶提取液的护色效果的影响,并探讨pH值对抑制剂及反应体系作用效果的影响,数据用SPSS软件处理,在25℃条件下,牛蒡与APTT比为0.5:3(g/mL)时,500μmol/L抑制剂对底物作用420s为最佳抑制反应条件,其ΔA为0.0082:pH7.0时,抑制效果最佳。APTT对牛蒡中酪氨酸酶有良好的抑制作用。     

荔枝酒制备过程中DDMP生成的适宜条件及变化规律

研究荔枝酒发酵过程中2,3-二氢-3,5-二羟基-6-甲基-4（H）-吡喃-4-酮（DDMP）生成的适宜条件,探明后期热处理及陈酿时间对DDMP生成的影响。结果表明,酿酒酵母（Saccharomyces cerevisiae）DV10最有利于DDMP的生成。发酵温度对DDMP的生成几乎没有影响,从荔枝酒的口感及品质上考虑,采用20 ℃的温度是较为适宜的发酵条件。响应面试验结果表明,适宜DDMP制备的条件为起始pH 4.2,发酵时间12 d,陈酿时间48 d。在此优化条件下得到的DDMP相对含量为0.15%。建议对荔枝酒进行热加速陈酿,进一步提高其功能品质。     

5-(4-(2-甲氧二氧)苯烯)-2-硫代噻唑-4-酮对雪莲果中酪氨酸酶的抑制作用

通过分光光度法探究5-(4-(2-甲氧二氧)苯烯)-2-硫代噻唑-4-酮(MBTO)对雪莲果中酪氨酸酶的抑制作用。结果表明：MBTO对雪莲果中酪氨酸酶有良好的抑制作用。单因素试验最佳抑制剂浓度为30.0μmol/L、最佳作用时间为210s、最佳作用温度为30℃。通过三因素三水平正交试验,分析得最佳反应条件为：pH7.5、抑制剂MBTO浓度30.0μmol/L、作用时间330s、作用温度30℃,可达到最佳抑制效果,在此条件下MBTO对雪莲果中酪氨酸酶的抑制率达84.24%。     

Detection and Quantification of 4(5)‐Methylimidazole in Cooked Meat

4(5)‐Methylimidazole (4‐MeI) is a nitrogen‐containing heterocyclic compound found in class III and IV ammoniated caramel colors, a group of additives widely used in the food industry. A suspected carcinogen and neurotoxin and efforts are underway to limit its presence in foods. Several methods have been developed to detect and quantitate 4‐MeI in different food matrices, including roasted coffee, beer, soft drinks, and soy sauce; however, no methods are available to measure 4‐MeI in cooked meat and meat products containing lipids and high levels of interfering nitrogen compounds, such as amino acids and peptides. A rapid method using 0.1 M sodium acetate buffer (pH 5) as an extraction solvent followed by derivatization with isobutylchloroformate and gas chromatograph mass‐spectrometry was developed to quantify 4‐MeI in cooked meat products with added caramel colors containing 4‐MeI. Selected ion monitoring mode was used to monitor 4‐MeI ions fragments. In the 8 commercial meat products tested, 4‐MeI levels ranged from 0.041 to 1.015 mg/kg, with recovery of 94.76% to 103.94%. In addition, a matrix‐matched calibration performed by analyzing a spiked cooked meat sample indicated no significant difference (P > 0.05), which means the meat matrix had no effect on the developed method. This method proved useful in analyzing 4‐MeI in meat products with added caramel color containing 4‐MeI.     

Formation of 4(5)‐Methylimidazole in Aqueous d‐Glucose‐Amino Acids Model System

The International Agency for Research on Cancer (IRAC) has classified 4(5)‐methylimidazole (4‐MeI) as a group 2B possible human carcinogen. Thus, how 4‐MeI forms in a d ‐glucose (Glu) amino acids (AA) model system is important, as it is how browning is affected. An aqueous solution of Glu was mixed individually in equimolar amounts at 3 concentrations (0.05, 0.1, and 0.15 M) with aqueous solutions of l ‐Alanine (Ala), l ‐Arginine (Arg), Glycine (Gly), l ‐Lysine (Lys), and l ‐Serine (Ser). The Glu‐AA mixtures were reacted at 60, 120, and 160 °C for 1 h. The 4‐MeI levels were measured by gas chromatography‐mass spectrometry after derivatization with isobutylchloroformate. No 4‐MeI was formed at 60 °C for any treatment combination; however, at 120 °C and 0.05 M, Glu‐Arg and Glu‐Lys produced 0.13 and 0.14 mg/kg of 4‐MeI. At 160 °C and 0.05 M all treatment combinations formed 4‐MeI. At 160 °C and 0.15 M, the observed levels of Glu‐Ala, Glu‐Arg, Glu‐Gly, Glu‐Lys, and Glu‐Ser were 0.21, 1.00, 0.15, 0.22, and 0.16 mg/kg. The AA type, reactant concentrations, and temperature significantly affected (P < 0.001) formation of 4‐MeI as well as browning. Glu‐Lys treatment in all combinations produced the most browning, but Glu‐Arg produced the most 4‐MeI. This method showed that foods processed using low temperatures may have reduced levels of 4‐MeI.     

Chemical constituents of Angiopteris esculenta including two new natural lactones

Angiopteris species (Angiopteridaceae) have been widely used in traditional Chinese medicine to treat many diseases. A.esculenta Ching was endemic to north-west of Yunnan Province, China, its rhizomes were used as a foodstuff by the local people for the extraction of starch. From the extracts of the aerial parts of the plant, two new natural lactones (5R,6R)-5,6-dihydro-5-hydroxy-6-methyl-2H-pyran-2-one (1) and (5R,6R)-5-(1-hydroxyethyl)-2(5H)-furanone (2), two known lactones, (5R,6R)-5-(1-hydroxyethyl)-dihydro-2-furanone (3) and angiopteroside (4), and six known compounds, coumarin (5), 5-(hydroxymethyl)furfural (6), 9(11)-fernene (7), β-sitosterol (8), d-fucose (9) and l-arabinose (10) were isolated and identified by using combination of mass spectrometry and various 1D and 2D NMR techniques. This is the first report of the chemical constituents of A. esculenta.     

Isolation of a mimosine degrading enzyme from leucaena leaf

An enzyme which catalyses the degradation of mimosine to 3-hydroxy-4(1H)-pyridone(DHP) has been isolated from Leucaena leucocephala leaf by extraction with ammonium sulphate, purification on Sephadex G-25 and fractionation on Sepharose 6B and gel electrophoresis. The enzyme was found to have a molecular weight of 140000, a K_m value of 1.64 mM ml^?1 and maximum reaction velocity of 0.3 mmol DHP produced ml^?1 min^?1. Tyrosine was a competitive inhibitor of the enzyme but DHP did not act as a feedback inhibitor. The enzyme has been termed ‘mimosinase'’.     

B(H)上的零点广义*-Lie可导映射

设(A)是一个代数,如果(A)a,b∈A且[aa*,b]=0,都有[φ(a)φ(a)*,b]+[aa*,φ(b)]-aφ(I)b+bφ(I)a=0,则称φ是(A)上的零点广义*-Lie可导映射.证明了B(H)上的零点广义*-Lie可导映射是广义内导子.