Transformations of Acids in the Course of Ozonolysis of Oxygen-containing Derivatives of Cycloparaffins

Transformations of monocarboxylic, dicarboxylic, and keto acids in the course of low-temperature ozonolysis were studied using the corresponding ¹⁴C-labeled compounds.     

Mechanism of Ozonolysis

The formation of ozonides (1,2,4-trioxolanes) from alkenes and ozone can be described as a succession of three [2+3] cycloadditions or cycloreversions involving primary ozonides (1,2,3-trioxolanes) and aldehyde or ketone oxides as decisive intermediates, all of which have finite lifetimes. There is no warranted experimental basis for assuming an alternative mechanism.     

Ozonolysis of ortho-alkenylanilines

Ozonolysis of N-acyl-2-(1-methylbut-2-enyl)- and N-acyl-2-(cyclopent-2-enyl)anilines followed by treatment with NaBH₄ afforded the corresponding 2-(2-hydroxyethyl-1-methyl) and 2-(1,5-dihydroxypent-2-yl) derivatives. The reaction can be directed to indole derivatives by varying the nature of both the acyl group and reducing reagent.     

Ozonolysis of naphthoquinones—I Ozonolysis of 1:4-naphthoquinone in chloroform

During ozonisation of 1:4-naphthoquinone in chloroform at −5 to −8° about 70 per cent undergoes anomalous ozonolysis forming phenylglyoxal-o-carboxylic acid and probably carbon monoxide. The remaining 30 per cent forms a normal ozonide which rearranges to a mixed anhydride of formic acid and phenylglyoxal-o-carboxylic acid. Sodium iodide reduction of the normal ozonide produces o-phenylenediglycolaldehyde. An intramolecular benzoin condensation of this substance is discussed.     

Ozonolysis of Ricinolic Acid Derivatives and Transformations of the Ozonolysis Products under Barton Reaction Conditions

The possibility of functionalizing the alkyl part of ricinolic acid using the Barton reaction was investigated. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 529–534, November–December, 2005.     

Ozonolysis of 1-Methylcyclohexanol

The kinetic features and composition of products of 1-methylcyclohexanol ozonolysis were studied.     

Mechanism of Methylcyclohexane Ozonolysis

A mathematical model of selective oxidation of methylcyclohexane with ozone-oxygen mixtures was substantiated.     

Ozonolysis of 3,4-dehydroproline

Ozonolysis of protected 3,4-dehydro- DL -proline ( 2 ) in methanol gives as the initially isolable product, a seven-membered ring cyclic peroxide ( 5 ). Compound 5 undergoes rearrangement thermally to give methyl N-tosylglycinate ( 8 ) and a stereochemical mixture of oxazolidine aldehyde esters ( 7 ). Structural evidence for 7 came from detailed ¹³C nmr studies of 7 and its reduction product ( 9 ).     

Ozonolysis of verbenone in methanol

The conditions of ozonolysis of verbenone in methanol strongly affect the mechanism of formation of the major product, (1R,3S)-3-acetyl-2,2-dimethylcyclobutane-1-carboxylic acid.     

水仙花开放期间香气组分变化的研究

采用活性炭吸附丝累积采集水仙花花开过程中不同时段的活体香气成分,采用居里点裂解器热解吸直接导入色谱-质谱仪进行定性定量分析,鉴定了苯甲醛、芳樟醇、柠檬烯、乙酸苄酯等55种香气组分,同时研究了水仙花开放过程中香气释放的变化规律。本方法操作简单,无需进行样品的预处理,可以方便地进行鲜花“活体”的香气成分采集与分析。     

Ozonolysis of perfluoroalkenes and perfluorocycloalkenes

Ozonolysis of 1-methoxyperfluorocyclobutene in Freon-113 followed by hydrogenation of the reaction products gave methyl hydrogen perfluorosuccinate. Under similar conditions, perfluorooct-1- and-2-enes and 4-trifluoromethyl-1,1,1,2,3,4,5,5,5-nonafluoropent-2-ene were converted into perfluorinated heptanoic, hexanoic, and isobutyric acids, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1239–1241, June, 1997.     

Mechanism of Cyclohexane Ozonolysis

A mathematical model of cyclohexane ozonolysis was developed. The reaction rate constants were found experimentally or by fitting.     

Ozonolysis of Methylcyclohexanols and Methylcyclohexanones

Ozonolysis of isomeric methylcyclohexanols and methylcyclohexanones was studied.     

Ozonolysis of phenols in aqueous solution

In the ozonolysis of phenol in aqueous solution at pH 3, 7 and 10 the following products were quantified: catechol, hydroquinone, 1,4-benzoquinone, cis,cis-muconic acid, H2O2, 2,4-dihydroxybiphenyl and 4,4-dihydroxybiphenyl. At pH 10, material balance (products vs. phenol consumption) is obtained. Singlet dioxygen, O2(1 delta g), and .OH are formed as short-lived intermediates. The precursor of the latter, O3.-, and a phenoxyl radical is suggested to arise from electron transfer from phenol/phenolate to ozone. Addition of .OH to phenol gives rise to dihydroxycyclohexadienyl radicals which add dioxygen and eliminate HO2. thereby forming catechol/hydroquinone. In competition and catalysed by H+ and OH-, the dihydroxycyclohexadienyl radical eliminates water yielding a phenoxyl radical. At pH 10, they readily oxidize catechol and hydroquinone. This reforms phenol (accounting for the low phenol consumption) and yields higher-oxidised products, eventually 1,4-benzoquinone. cis,cis-Muconic acid can be accounted for by the Criegee mechanism, while O2(1 delta g) is released on the way to (some of the) catechol and hydroquinone. Similar reactions proceed with hydroquinone (products: 1,4-benzoquinone, 2-hydroxy-1,4-benzoquinone and H2O2, with high yields of O2(1 delta g) and .OH) and with catechol (products: 2-hydroxy-1,4-benzoquinone, cis,cis-muconic acid, H2O2 with high yields of O2(1 delta g) and .OH). Material balance is not obtained for these two systems. Pentachlorophenolate, pentabromophenolate and 2,4,6-triiodophenolate ions give rise to halide ions, O2(1 delta g) (58%/48%/10%) and .OH (27%/2%/0%). It is suggested that together with O2(1 delta g) the corresponding ortho- and para-quinones plus a halide ion are formed. Further halide ion is released upon the hydrolysis of these and other products. For pentachlorophenolate the material balance with respect to the short-lived intermediates is 85%. With the bromo- and iodophenolates the O2(1 delta g) yields are substantially lowered, most likely due to release of triplet (ground state) dioxygen induced by the heavy atom effect.     

丙烯的臭氧化反应动力学研究

使用自行研制的烟雾箱实验装置, 研究了模拟实际大气环境臭氧浓度下(最小浓度6.6×10−8)臭氧与丙烯的反应动力学. 结合Model 49C-O3 Analyzer与GC-FID对臭氧与丙烯在282~314 K温度范围内的速率常数进行了测定, 得到臭氧初始浓度为6.61×10−8、温度为282 K时臭氧与丙烯的反应速率常数为6.73×10−18 cm3•molecule−1•s−1. 并根据不同温度下测得的反应速率常数, 求得该反应的阿仑尼乌斯方程为k2=(5.8±1.2)×10−15e(−1907±53)/T. 对比前人结果, 我们测得的速率常数偏小, 活化能偏高, 但速率常数的最大误差仅为11%, 活化能的最大误差为5%. 说明我们的研究设备在实际大气条件下是可靠的, 可用于进一步深入研究臭氧有关的反应.     

对功能高分子课程教学的思考

功能高分子的设计思想是功能高分子课程的灵魂 ,它以高分子物理学所研究的结构与性能之间关系为基础。结构与性能之间的关系是贯穿功能高分子课程始末的主线。功能高分子材料有三种设计途径 ,即化学结构设计、聚集态结构设计和复合结构设计