角黄素合成工艺研究

本文以碘化钾、双氧水代替碘作为催化剂,用氯酸钠作为氧化剂,在酸性环境下以β-胡萝卜素为原料一步氧化法生产角黄素。同时,对各个反应条件进行了工艺优化,得到了最优条件,角黄素总收率可以达到78%。结果证明:该工艺路线条件温和,收率高,工艺稳定、可靠。     

CO2在绿色化学合成中的应用

研究了CO2在绿色化学合成中的应用.CO2作为酸碱调节剂和惰性气体,在β-胡萝卜素催化氧化合成角黄素反应中,可以控制反应体系酸性,保护原料中的双键,减少副反应发生,提高催化氧化反应的选择性;异戊二烯氯醇化生成1-氯-2-甲基-3-丁烯-2-醇和1-氯-2-甲基-3-丁唏-4-醇反应中,CO2代替有机酸作酸碱调节剂,控制次氯酸的生成速度,达到调控反应的目的,反应条件温和,不副产固体.     

β-胡萝卜素的合成工艺改进

采用Wittig Horner法合成β 胡萝卜素,以3 甲基 5 (2,6,6 三甲基 1 环己烯 1 基) 1,3(或1,4) 戊二烯膦酸二烷基酯直接与2,7 二甲基 2,4,6 庚三烯 1,8 二醛反应合成目标产物,收率60%,与JamesH.Bable所申请的专利(US:4916250,1990)的方法相比不但省掉了一步碱催化的双键重排反应,而且收率提高10%。1HNMR,IR,MS显示与对照品一致。     

还原耦联法合成β-胡萝卜素

研究还原耦联法合成β-胡萝卜素。以维生素A醛为原料,通过过渡金属与维生素A醛在一起,金属本身氧化,维生素A醛的羰基还原并耦联成双键,得到β-胡萝卜素产品。在研究还原耦联制备β-胡萝卜素的过程中,对过渡金属钛试剂制成溶剂化试剂进行探讨,解决了钛试剂的稳定性问题,并提高了过渡金属的耦合能力;对还原剂进行活化,提高了还原剂的还原能力;在还原耦联反应中添加氯硅烷,达到催化产生羰基耦联反应的目的。结果表明,合成的β-胡萝卜素含量达到98%以上,收率达到80%以上。     

蒜头果油合成1,15-十五碳二酸二甲酯的研究

研究了由蒜头果油制取1,15-十五碳二酸二甲酯的3种合成路线,比较了3种合成路线中臭氧化的吸收特征.结果表明,合成路线一为5步反应,1,15-十五碳二酸二甲酯收率为26.9%;路线二为4步反应,1,15-十五碳二酸二甲酯收率为61.7%;路线三为3步反应,1,15-十五碳二酸二甲酯收率为68.1%.通过对比确定路线3是最佳合成方案.用拟水平正交试验法对路线3的酯化反应进行优化,确定最佳的反应条件是:反应温度70 ℃左右;催化剂用量与原料比为1∶5(v·m-1);反应时间2 h.该优化条件可使1,15-十五碳二酸二甲酯收率达到72.4%.     

2-(3-氯-2-氧代基)异吲哚啉-1,3-二酮合成工艺改进

[目的] 2-(3-氯-2-氧代基)异吲哚啉-1,3-二酮是合成5-氨基乙酰丙酸的中间体,用催化氧化方法进行了合成。[方法]以邻苯二甲酰亚胺钾为主要原料,经与和环氧氯丙烷反应制备N-(2,3-环氧丙基)邻苯二甲酰亚胺,再经盐酸水解,TEMPO催化下PhI(OAc)_2氧化得到目标产物。[结果]在优化的反应条件下,2-(3-氯-2-氧代基)异吲哚啉-1,3-二酮的反应收率为93.1%。催化剂TEMPO可回收套用2次。结构经氢谱核磁分析确证。[结论] 2-(3-氯-2-氧代基)异吲哚啉-1,3-二酮合成工艺具有污染小、收率高和易于工业化生产等优点。     

一锅法合成β-三氟甲基-α-甲基-α、β-不饱和酸酯

正丁基锂在-78℃攫取(α-烷氧羰基)乙基膦酸二乙酯(1)的活泼氢得到碳负离子2,其进攻三氟醋酸酐产生三氟乙酰基膦酸酯(3);不经过分离,直接用Grignard试剂进攻三氟乙酰基膦酸酯(3),由HWE反应选择性地合成了以Z-式为主的β-三氟甲基-α-甲基-α、β-不饱和酸酯(4),按1计,三步反应的总收率为59%～92%,Z-构型反应产物是主要产物。     

蒜头果油中长链脂肪酸选择性合成大环内酯

研究了蒜头果油脂中长链不饱和脂肪酸的臭氧氧化以及ω-羟基脂肪酸的催化关环合成大环内酯,考察了臭氧氧化切断双键选择性和大环内酯化选择性。结果表明,不饱和脂肪酸的碳链越长,越有利于臭氧氧化反应和生成大环内酯。蒜头果油脂合成大环内酯的产率为:环十五内酯36.9%,环十三内酯为22.4%,环十一内酯1.0%,并探讨了蒜头果油脂中油酸的反应特性。     

7-氯-2-氧代庚酸乙酯的合成

7-氯-2-氧代庚酸乙酯是合成西司他丁的中间体。以二氯乙酸为起始原料,酯化制成2,2-二乙氧基乙酸乙酯,收率55·6%,2,2-二乙氧基乙酸乙酯与1,3-丙二硫醇成环生成1,3-二噻烷-2-羧酸乙酯,收率72·4%;1,3-二噻烷-2-羧酸乙酯再与1-溴-5-氯戊烷烷基化反应后经氧化到7-氯-2-氧代庚酸乙酯,收率80%。本路线简化了2,2-二乙氧基乙酸乙酯的合成工艺,用1-溴-5-氯戊烷代替1,5-二溴戊烷,减少了双烷基化副反应,使收率有所提高。     

乙酸丁酯液相合成丙烯酸丁酯的工艺研究

采用乙酸丁酯液相合成丙烯酸丁酯,通过双键来源和催化剂种类的筛选,以催化剂A-X催化1,3-二氧五环与乙酸丁酯的反应效果较佳。通过考察反应时间对反应的影响推得其反应进程,主反应分为两步:第1步(R1)为1,3-二氧五环与乙酸丁酯反应生成二丁氧基甲烷和乙二醇二乙酸酯;第2步(R2)为二丁氧基甲烷与乙酸丁酯反应生成丙烯酸丁酯和正丁醇。较优的工艺条件为:反应温度180℃,催化剂A-X用量37.5%(以1,3-二氧五环为基准),初始压力0.50 MPa。在该条件下,1,3-二氧五环的转化率为96.8%,丙烯酸丁酯的选择性和收率分别为37.6%和36.4%。     

β-Carotene and lipid oxidation

The relevant recent literature regarding the antioxidant properties of β-carotene as a radical scavenger and singlet oxygen quencher in lipid oxidation is presented and discussed. In this connection, a brief information about the biological activity of β-carotene is also given. As the antioxidative behaviour of β-carotene is closely related to its own oxidation, the rate and mechanism of oxidative degradation of β-carotene at different conditions are also presented. Taking into account the results of the papers discussed in this review, further investigations of the cooperative action of β-carotene with other natural antioxidants, e.g., non-toxic flavonoids, phenolic acids, coumarins, etc., should be carried out. This is recommended in view to obtain new types of edible fats and lipid containing products with high oxidation stability, which, at the same time, could serve as functional foods with positive effects on our nutrition and health.     

Pro-Oxidant Effects of β-Carotene During Thermal Oxidation of Edible Oils

β-Carotene is one of the most important fat soluble pigments with well-known antioxidant and pro-vitamin A activity. It is used in industries as a food colorant and a source of vitamin A. The thermal induced degradation during processing of wide varieties of carotenoid-rich foods leads to color and properties losses. The thermal stability of edible oils is thus of great importance to food manufacturers. Corn oil, rapeseed, and sunflower oils were fortified with 50–300 μg/g of β-carotene and oxidized using a Rancimat apparatus (air flow rate 20 L/h) at 110 °C for 14 h. β-Carotene degradation was measured using high performance thin layer chromatography and confirmed by HPLC–DAD–MS. Triacylglycerols and polar compounds (PC) were determined using LC–ESI–MS. Results showed that most of the β-carotene was degraded during the first 5 h of the thermal oxidation. It was found that the addition of β-carotene produces significant effects (P < 0.05) on the peroxide index, free fatty acid values and radical scavenging activity of the three oils. Triacylglycerols containing high amounts of oleic acid show higher stability toward thermal oxidation and β-carotene treatment. Among the oils, rapeseed oil was the most stable oil in terms of the formation of polar compounds (PC), followed by corn oil, while sunflower oil was more prone to oxidation and thus higher amounts of PC were formed.     

K系维生素中间体β-甲基萘醌的合成工艺研究

本实验研究了一种新颖且环境友好的β-甲基萘醌的合成方法。该方法以冰醋酸为溶剂,OP-10为乳化剂,过氧化氢作为氧化剂,氧化p-甲基萘制取β-甲基萘醌。分别考察了反应温度、反应时间、β-甲基萘与冰醋酸摩尔比等因素对β-甲基萘醌转化率和收率的影响。从而得到较优反应条件为：反应温度100℃;反应时间4h;n（β-甲基萘）：n（冰醋酸）为1：16;n（β-甲基萘）：n（H2O2）为1：11;OP-10用量0．05ml／g（β-MN）。在此条件下,β-甲基萘醌的转化率可达96％,收率可达52％。     

Anti- and Prooxidant Properties of Carotenoids

Carotenoids can be effective singlet oxygen quenchers and inhibit free-radical induced lipid peroxidation. A remarkable property of β-carotene ( 1a ) is the change from an antioxidant to a prooxidant depending on oxygen pressure and concentration. In the present study a considerable number of carotenoids ( 1a , 2c , 2d , 2e , 3a , 4a , 5a , 6a , 7a , 8a , 8h , 8i , 8j , 9f , 10a , 11a , 12g ) was investigated using two independent approaches: 1. Comparison of their effects on inhibition of the free-radical oxidation of methyl linoleate, and 2. The direct study of the effect of oxygen partial pressure upon their rates of oxidation. It is shown that some carotenoids ( 7a , 8a ) are even more effective than the well-known compounds β-carotene ( 1a ) and astaxanthin ( 5a ) and are powerful antioxidants without any prooxidative property. Different carotenoids display different behaviour depending on chain length and end groups. The influence of these functional groups on the antioxidative reactivity is discussed.     

Antioxidants and stabilizers. LXV. Contribution to the investigation of sensitized photooxidation of phenolic antioxidants. Quenching of singlet oxygen with stilbenequinoid compounds

The photooxidation of 2,6-di-tert-butyl-4-methylphenol (I) and 2,2′-methylene-bis(4-methyl-6-tert-butylphenol) (II) sensitized with methylene blue in dichloromethane was investigated. The oxidation of phenol I proceeds at a reduced rate, but otherwise similar to the oxidation in methanol, that is, with the formation of 2,6-di-tert-butyl-4-methyl-4-hydroperoxy-2,5-cyclohexadiene-1-one (III, R = tert-butyl). On the other hand, bisphenol II remains almost unoxidized in dichloromethane. This is due to the formation of stilbenequinoid derivatives of type VI which slow down the oxidation even at insignificant concentrations. The effect approaches that of β-carotene. Phenol I has a much weaker tendency towards the formation of an analogous derivatives, i.e. 3,5,3′,5′-tetra-tert-butylstil-benequinone (VIII), which however is also an active retarder of oxidation. A more detailed study carried out with VIII indicates that the mechanism of its effect is the same as for β-carotene, that is, the quenching of singlet oxygen. Stilbenequinone VIII used in a fourfold concentration has almost the same effect as β-carotene, but unlike the latter it is much more stable towards oxidation. The activity of VI lies between that of stilbenequinone VIII and β-carotene.     

A new approach to deep desulfurization of gasoline by electrochemically catalytic oxidation and extraction

In order to further reduce the sulfur content in gasoline, a new desulfurization process for gasoline was obtained by means of electrochemically catalytic oxidation and extraction with an electrochemical fluidized-bed reactor. The particle group anode was activated carbon-supported lead dioxide (β-PbO₂/C). The electrolyte was aqueous NaOH solution, and copper pillar was cathode in the electrochemical reactions. The β-PbO₂/C particle group anodes can remarkably accelerate the electrochemical reaction rate and promote the electrochemical catalysis performance for the electrochemical desulfurization reaction. Also, gasoline desulfurization rule was investigated in an alkali solution. The experimental results indicated that the optimal desulfurization conditions were as follows: the cell voltage, the pH value of the electrolyte, feed volume flow rate and the β-PbO₂ percentage by weight were 3.2 V, pH value 13.1, 300 ml min^{− 1} and 5.0 wt.%, respectively. Under these conditions the concentration of sulfur in gasoline was reduced from 310 to 40 μg g^{− 1}, and the main properties of the product were not significantly affected. Based on these experimental results, a mechanism of indirect electrochemical oxidation was proposed.     

高效液相色谱法测定烟草样品中的叶黄素和β-胡萝卜素

研究了用固相萃取和高效液相色谱法测定烟草样品中的叶黄素和β 胡萝卜素;烟草样品中的叶黄素和β 胡萝卜素用90%的丙酮震荡萃取,然后用WatersSep Park C18固相萃取小柱预分离和富集,以WaterNova Pak C18色谱柱为固定相,(1+1)甲醇异丙醇溶液 水梯度洗脱为流动相,二极管矩阵检测器检测测定。该方法标准回收率为96%～104%,RSD%为1.26%～2.43%;用于烟草中叶黄素和β 胡萝卜素的测定,结果满意。     

紫苏叶干燥产品主要营养成分分析

紫苏叶富含β-胡萝卜素和多种矿物质元素，新鲜的紫苏叶经75℃鼓风干燥加工后，其β-胡萝卜素含量为678．89μg／g，Ca^2＋、Fe^2＋和Zn^＋含量分别为13742．17μg／g、211．43μg／g和22.38μg/g。腌渍紫苏叶的β-胡萝卜素含量仅为新鲜紫苏的41％。     

Experimental measurement and correlation of solubility of β-carotene in pure and ethanol-modified subcritical water

For the first time, the solubility of β-carotene in pure and ethanol-modified subcritical water (SW) using the static method was determined. The experimental runs were performed at a temperature ranging from 298.15 to 403.15 K and 0-10% (w/w) of ethanol as a modifier at a constant pressure of 5 MPa. Samples were analyzed by UV-vis spectrophotometer. The solubility of β-carotene was found to range from 1.084×10^-8 to 227.1×10^-8 mol fractions in the subcritical water in above mentioned conditions. The obtained β-carotene solubility data were correlated using the linear model and modified Apelblat model. The obtained results showed the modified Apelblat model was better for estimating the solubility of β-carotene in SW. The values of the rootmean-square deviation (RMSD) between experimental and correlated data were calculated and used as the index of validity and accuracy for the model. Also, thermodynamic properties of the solution such as the Gibbs free energy of solution, enthalpy, and entropy of solution were estimated.     

Carotenoid Composition and Vitamin A Values of Oils from Four Brazilian Palm Fruits

In oils extracted from fresh and sterilized palm fruits (Elaeis guineensis, Jacq. tenera, dura dumpy and psifera and E. oleifera), cis-phytofluene, 13-cis-α-carotene, α-carotene, 13-cis-β-carotene, β-carotene, 9-cis-β-carotene, σ-carotene, zeaxanthin, --cryptoxanthin, poly-cis-lycopene, mono-lycopene and lycopene, were identified and quantified by normal phase open column chromatography (stepwise-elution), TLC, UV/Vis spectroscopy and specific chemical reactions. The sum of α- and β-carotene in all samples analysed was higher than 80% of the total carotenoid content, while the α/β-carotene ratios were W.9, 1/11.1, 1/22 and V2.6 for oils extracted from fresh fruits of dura dumpy, psifera, tenera and E. oleifera, respectively. Total carotenoid contents (pg/g) and vitamin A values (R. E./100 g) of these samples were 1 120.7 and 12 404 for dura dumpy, 283.2 and 3612 for psifera, 660.5 and 7630 for tenera and 1576.8 and 21691 for E. oleifera. The sterilization of fruits (127°C × 35 min.) resulted in isomerization of pigments and reduction of vitamin A values of approximately 45% and 25%, respectively.