酸处理活性炭催化臭氧氧化肉桂醛为苯甲醛

以经酸处理的活性炭为催化剂,进行多相催化臭氧氧化肉桂醛为苯甲醛。考察了溶剂种类、乙醇用量、活性炭用量、臭氧流量及臭氧化反应温度对反应的影响。结果表明,活性炭能够明显提高臭氧的利用率,臭氧利用率从单独使用臭氧时的53.5%提高到67.4%。最佳反应条件为:无水乙醇为溶剂,m(无水乙醇)/m(肉桂醛)=3,氧气流量为800 mL/min(臭氧流量为0.71 g/h),m(活性炭)/m(肉桂醛)=0.01,在0℃下臭氧化反应2 h,然后进行还原反应,苯甲醛收率为44.0%。     

臭氧化反应过氧化物中间体测定

以肉桂醛为起始原料,通过设计的臭氧化反应装置进行臭氧化反应,制备臭氧化过氧化物,而后加入二甲硫醚还原过氧化物。参照国家标准碘量法直接测定反应体系过氧化物质量分数,并做空白实验扣除反应体系残余臭氧质量分数即可计算出体系内残余臭氧化过氧化物中间体质量分数。     

三种苯乙烯烃臭氧化反应活性的研究

采用气相色谱对苯乙烯—肉桂醛、苯乙烯—茴脑二元混合物和苯乙烯—肉桂醛—茴脑三元混合物的臭氧化反应选择性进行反应过程跟踪研究 ,得出了三种苯乙烯烃的反应活性大小顺序是茴脑 >苯乙烯 >肉桂醛。并考察了基团对臭氧化反应活性的影响     

天然棉籽油臭氧化反应机理及过程研究

为了研究天然棉籽油在不同溶剂中的臭氧化反应历程,合成高过氧化值的臭氧化油,以棉籽油为原料,通过臭氧氧化制备了一系列臭氧化油,利用红外光谱(IR)、核磁氢谱(1H-NMR),异核碳氢相关谱(HMQC)和长程异核碳氢相关谱(HMBC)解析了棉籽油中双键臭氧化的反应历程和产物结构,并优化了乙酸乙酯溶剂体系的臭氧化过程的工艺条件。结果表明:乙酸乙酯溶剂中,羰基氧化物与醛反应,主要产物为臭氧化物;而甲醇溶剂中,羰基氧化物易与过量醇发生反应,主要产物为过氧羟基和甲氧基的双官能团产物;在棉籽油的加入量为25 g,进口臭氧浓度80 mg/L,进口流量3 L/min,乙酸乙酯添加量50 g,反应时间2 h下,棉籽油双键转化率可达99%,产物过氧化值为1 990.73 mmol/kg,所获得的臭氧化棉籽油热稳定性好。     

臭氧化反应的研究与应用

综述了烯烃臭氧化反应的理论和应用研究进展。从臭氧化反应Criegee机理出发，介绍了初级臭氧化物和臭氧化物的结构和化学性质以及近年来研究者对其研究的拓展，同时介绍了臭氧化物不同的裂解方式。臭氧化物不同的裂解方式可以得到不同的产物。加上臭氧化反应本身的优点，为臭氧化反应在合成上的应用打下了基础。结合实例，介绍了臭氧化反应在二元酸及其它重要中间体的合成上的应用。     

臭氧化反应在香料工业中的应用

臭氧(O_3)常用来氧化不饱和烯烃化合物然后分解生成两个较小的分子——醛、酮或醇。由于臭氧化反应非常迅速,即使在极其温和的条件下,双键也能定量地开裂,所以臭氧化反应有时也被用来确定双键的位置和测定不饱和化合物的结构。进行臭氧化反应时,通常是将臭氧通入烯烃化合物的四氯化碳、石油醚或醋酸溶液中,臭氧加成在双键上,并生成不稳定的臭氧化物;臭氧化物与水作用,即分解成醛或酮:     

陶瓷粉体催化臭氧化降解水中苯酚

将陶瓷粉末应用于降解苯酚废水用臭氧化催化剂,表征了陶瓷的化学组成、0电荷pH和表面羟基密度,并考察了反应条件的影响.结果表明,陶瓷粉末对于臭氧化降解质量浓度为100mg·L-1的模拟苯酚废水具有较为显著的催化效果.不同温度的影响试验表明,在278～308 K时,苯酚的降解速率随温度升高而加快,然而(与单独臭氧化比较)在较低温度下陶瓷的催化效果更加显著.结合羟基自由基清除剂的影响试验,推断在催化臭氧化过程中臭氧分子和羟基自由基共同氧化污染物,陶瓷粉末的表面羟基促进了臭氧分子到羟基自由基的转变,因而加快了臭氧化过程.     

臭氧氧化合成臭葱石除砷

用臭氧发生器产生的臭氧氧化模拟酸性含砷废水,在95℃下加热反应7 h合成臭葱石,考察了Fe(II)氧化速率及溶液初始pH值对砷去除率及臭葱石合成的影响. 结果表明,提高Fe(II)氧化速率及增大初始pH值均可促进As沉淀. 初始pH为2.0时通入臭氧,溶液中As的最终去除率可达89.64%,反应所得臭葱石颗粒尺寸较大、结晶良好.     

天然肉桂油臭氧化制取苯甲醛

利用天然肉桂油中富含的肉桂醛，经过臭氧化反应和还原反应制得了苯甲醛。由该法制得的苯甲醛在国际上可作为天然苯甲醛使用。     

3,4-二甲氧基苯丙酮的合成研究

研究了以呋喃酚的副产物4-(2-甲基烯丙基)-1,2-苯二酚为原料,经醚化、臭氧化得附加值较高的精细化工产品3,4-二甲氧基苯丙酮。分析了醚化、臭氧化反应过程中可能出现的副反应。探索了醚化反应的氢氧化钠用量、反应温度和臭氧化反应的反应温度、臭氧用量等条件,优化条件为醚化反应n(NaOH)∶n(4-(2-甲基烯丙基)-1,2-苯二酚)=2.25∶1.00,反应温度为90℃,臭氧化反应温度℃、n(O_3)∶n[1,2-二甲氧基-4-(2-甲基烯丙基)苯]=3∶1时,合成3,4-二甲氧基苯丙酮总收率达72.8%,产品结构经LC-MS,~1H NMR确证。     

Adhesive properties onto galvanized steel plates of grafted poly(vinylidene fluoride) powders with phosphonated acrylates

Hydrophilic fluoropolymers were obtained by grafting phosphonated monomers onto activated poly(vinylidene fluoride) (PVDF). By using an ozonization technique, dialkylperoxide and hydroperoxide groups were formed onto PVDF which may be decomposed thermally in a subsequent step to initiate graft copolymerization. By using an iodometric titration technique, the effect of ozone oxidation time and temperature on the concentration of peroxides was studied. However, degradation was observed by viscosimetry and FTIR for the hardest ozonization conditions. An effect of the grafting conditions (monomer concentration and monomer end groups) on the degree of grafting was determined and diester‐acrylated phosphonate is grafted at a higher rate than are the homologous acid derivatives. Adhesion of the graft copolymers applied to galvanized steel substrates was studied. The experiments clearly show stronger adhesive properties of PVDF coatings containing phosphonic acid functions than those of the ones containing carboxylic acid functions. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 611–620, 1999     

Synthesis and characterization of ozonized polyethylene

Polyolefins (LDPE and HDPE) can be ozonized with ozone/air gas flow to create peroxide and hydroperoxide groups on polymers. These reactive groups can be used to initiate radical polymerization of vinylic monomers and produce graft copolymers. In this study, the optimization of the experimental conditions and the explanation of the phenomena occurring during the ozonization of polyolefins in a fluidized bed have been studied. The most reproducible methods for placing peroxide and hydroperoxide groups onto polyolefins are the iodometric method and indirect titration by thiol. This work shows that it is necessary to control the temperature of the fluidized bed to avoid the acceleration of the reaction and the degradation of the polymers. Then, we studied the effect of different parameters such as the crystallinity and the granulometry of polymers, the time of ozonization and the effect of the load of the reactor on the quality of ozonization. Infrared spectroscopy and steric exclusion chromatography were used to characterize the ozonized polymers. We show that double bonds of PE, particularly vinyl groups, are very reactive to ozone and that ozonized HDPE leads essentially to the formation of hydroperoxide groups, whereas ozonized LDPE leads to the formation of peroxide groups.     

Comparison of four analytical methods for the determination of peroxide value in oxidized soybean oils

Previous work in our laboratory demonstrated that soybean oil oxidation, expressed as PV, can be determined using NIR transmission spectroscopy as an alternative to the official AOCS iodometric titration method. In the present study, a comparison of four peroxide analytical methods was conducted using oxidized soybean oil. The methods included the official AOCS iodometric titration, the newly developed NIR method, the PeroxySafe^™ kit, and a ferrous xylenol orange (FOX) method, the latter two being colorimetric methods based on oxidation of iron. Five different commercially available soybean oils were exposed to fluorescent light to obtain PV levels of 0–20 meq/kg; periodic sampling was done to ensure having representative samples throughout the designated range. A total of 46 oil samples were analyzed. Statistical analysis of the data showed that the correlation coefficient (r) and standard deviation of differences (SDD) between the standard titration and NIR methods were r=0.991, SDD=0.72 meq/kg; between titration and the PeroxySafe^™ kit were r=0.993, SDD=0.56 meq/kg; and between the standard titration and FOX method were r=0.975, SDD=2.3 meq/kg. The high correlations between the titration, NIR, and PeroxySafe^™ kit data indicated that these methods were equivalent.     

Chemical analysis of ozonized theobroma fat

Ozonized theobroma fat is used as raw material in the manufacture of pessaries and cosmetic creams. Ozonization of theobroma fat with water was carried out at different applied ozone dosages, and the resultant PV, acid value, iodine value, total hydroperoxide content, and FA content were determined. PV and total hydroperoxide content showed a notable increase with applied ozone dosage up to 35.7 mg/g. Acid value varied slightly from 4.1 to 9.9 mg KOH/g, and the iodine value fell to zero. PV and total hydroperoxide content increased slightly with a higher applied ozone dosage. The comparison of total hydroperoxide measurement using ferrous oxidation in xylenol orange assay and traditional iodometric assay for PV determination showed a significant linear correlation. Small amounts of oleic acid were found in ozonized theobroma fat samples with iodine value equaling zero, which demonstrated that iodine value determination is an inexact assay. During ozonization of theobroma fat, an increase in acid value of 18.9-fold with respect to the initial value was observed owing to decomposition of peroxide.     

Determination of the iodine value of biodiesel using H NMR with 1,4-dioxane as an internal standard

Iodine values (IVs) of some biodiesel samples were analyzed using both ¹H NMR and a standard iodometric method. ¹H NMR was carried out with and without 1,4-dioxane as an internal standard (IS). The results obtained using ¹H NMR with 1,4-dioxane as an internal standard showed better linear fitting and correlation with the iodometric method than NMR without the IS. The proposed ¹H NMR_IS method allows determination of the IV using smaller samples than the iodometric method. Moreover, the determination can be carried out in less than 15 min, dramatically less than the time needed to carry out the iodometric method.     

HPLC法测定肉桂油巴布剂中桂皮醛的含量

建立测定肉桂油巴布剂中桂皮醛含量的方法。采用高效液相色谱法,DiamoonsilC18(2)(4.6mm×250mm,5μm)色谱柱,流动相为乙腈—水—冰醋酸(体积比50:50:0.3),流速1.0mL.min-1,检测波长290 mn。桂皮醛进样量在1.4625~46.8μg/mL范围内与峰面积线性关系良好,回收率为98.12%。本方法测定结果准确、重复性好,可用于该制剂的桂皮醛含量测定。     

复合二氧化氯消毒剂有效含量的定义

复合二氧化氯在饮用水消毒方面的应用越来越广泛,但消毒剂含量定义的问题一直争论不休。该文提出"总有效氯"为复合二氧化氯作为消毒剂中有效氯含量的定义,即pH在中性条件下,二氧化氯折算成氯的质量浓度乘以1(从ClO2还原到ClO2-,氧化价态变化值为1),再加上氯气质量浓度。"总有效氯"可用国标推荐五步碘量法的第一步(pH=7),方法应用简单、结果稳定、可靠。测定饮用水中余氯用DPD分光光度法比碘量法更好。如果二氧化氯与氯比值为1.0,则国标中的"有效氯"是"总有效氯"的2.3倍。     

肉桂醛低浓度碱性水解反应体系的研究

利用等吸收点建立了紫外分光光度法定量分析肉桂醛、苯甲醛和5-苯-2,4-戊二烯醛三组分的方法,构建了组分浓度与吸光度之间的关系:CPPDA=(A338+0.038 9)/0.174 0,C肉桂醛=(A303-0.117 7CPPDA)/0.113 8,C苯甲醛=(A255-0.042 7C肉桂醛-0.020 9CPPDA)/0.059 7,研究了肉桂醛在低浓度40~60℃条件下的水解反应。结果表明,水解反应速率随温度降低趋于缓慢,反应时间越短副反应越少。采用一级反应动力学模型对动力学数据进行拟合,得到肉桂醛水解反应的活化能为56.59 kJ/mol。     

库仑滴定法测定油田水中的硫离子

采用库仑滴定法测定油田水中的硫离子含量。在pH=5.0的HAc-NaAc缓冲液中,I-在Pt工作电极上电解析出滴定剂I2,I2可定量滴定溶液中的S2-。方法适用于微量、常量分析,相对标准偏差为1.3%（n=10）,与碘量法对比,两者结果无显著性差异。该方法具有简便、快速等优点,用于油田水中硫离子的测定,结果满意。