Radiolytic oxidation of propane: Computer modeling of the reaction scheme

The oxidation of gaseous propane under gamma radiolysis was studied at 100 torr pressure and 25°C, at oxygen pressures from 1 to 15 torr. Major oxygen-containing products and their G-values with 10% added oxygen are as follows: acetone, 0.98; i-propyl alcohol, 0.86; propionaldehyde, 0.43; n-propyl alcohol, 0.11; acrolein, 0.14; and allyl alcohol, 0.038. Minor products include i-butyl alcohol, t-amyl alcohol, n-butyl alcohol, n-amyl alcohol, and i-amyl alcohol. Small yields of i-hexyl alcohol and n-hexyl alcohol were also observed. There was no apparent difference in the G-values at pressures of 50, 100 and 150 torr. When the oxygen concentration was decreased below 5%, the yields of acetone, i-propyl alcohol, and n-propyl alcohol increased, the propionaldehyde yield decreased, and the yields of other products remained constant. The formation of major oxygen-containing products was explained on the basis that the alkyl radicals combine with molecular oxygen to give peroxyl radicals; the peroxyl radicals react with one another to give alkoxyl radicals, which in turn react with one another to form carbonyl compounds and alcohols. The reaction scheme for the formation of major products was examined using computer modeling based on a mechanism involving 28 reactions. Yields could be brought into agreement with the data within experimental error in nearly all cases.     

Type 3 ring opening reaction of cyclopropanated oxabenzonorbornadienes with alcohol nucleophiles

The first examples of a Type 3 ring opening reaction of cyclopropanated oxabenzonorbornadiene (CPOBD) were found to occur using alcohol nucleophiles under acid catalyzed conditions, yielding seven-membered rings via ring expansion. Optimization of the reaction determined the ideal conditions to be 10?mol% pTsOH at 40?°C using excess alcohol nucleophile as the solvent. The scope of the reaction investigated diverse alcohol nucleophiles and bridgehead substituents on the CPOBD; in both cases the steric properties of the substituent was found in influence the yield of the reaction. Alternative Type 3 products were observed when the bridgehead substituent was an ethyl or hydroxymethyl group and limited examples of Type 3 products were formed using a palladium catalyst with alcohol nucleophiles. Mechanisms have been proposed for the formation of the Type 3 product as well as the alternative Type 3 products.     

对丙基苯甲酸的钠还原反应

醇钠可以还原对丙基苯甲酸中的苯环.不同的醇作溶剂,反应时间及钠的用量不同,还原产物中各组分含量不同;完全还原产物的含量随醇的酸性增加而减少;对正戊醇而言,钠的用量达到一定量时,还原产物的组成近似恒定.     

Reactions of sodium sulphide—I : With compounds containing hydroxyl groups

Aqueous solutions of sodium sulphide (ca 10%) reagent were reacted at 250° with compounds containing OH groups. This work was part of a programme designed to test the usefulness of the Na₂S solution degradation technique for determining the primary structure of humic acids. The compounds reacted here and the principal products detected (shown in brackets) were: cinnamyl alcohol (benzyl alcohol, benzoic acid, 3-phenylpropan-1-ol, 3-phenylpropionic acid), benzyl alcohol (little reaction), 3-phenylpropan-1-ol (little reaction), 1,2-dihydroxy-1-phenylethane (phenylacetic acid, acetophenone, 1-phenylethanol), catechol and hydroquinone (recovered starting compounds+ polymer products). Sodium hydroxide gave the same products with cinnamyl alcohol, but in different proportions. Possible mechanisms for these reactions are discussed.     

聚甲基乙烯基酮的不对称还原反应

聚甲基乙烯基酮的不对称还原反应李弘姚金水何炳林（吸附与分离功能高分子材料国家重点实验室南开大学高分子化学研究所天津３０００７１）关键词对称硅氢化，聚甲基乙烯基酮，手性噻唑烷，铑近年来手性过渡金属络合物催化的前手性酮和烯的不对称硅氢化反应已在国际上受...     

Radiolysis of benzyl alcohol in aqueous solution

Radiolysis of 0.05% aqueous solution of benzyl alcohol with 50Co gamma-rays ranging from 1 X 10(4) to 7 X 10(5) rad was investigated, in order to presume the change of it contained in radiopharmaceuticals. For both O2 free and oxygenated solutions, an approximately linear relationship holds between the retaining benzyl alcohol and dose in the range from 1 X 10(5) to 7 X 10(5) rads. The G(-M) values of benzyl alcohol calculated from the relation were 2.34 in the absence and 1.92 in presence of oxygen. In the presence of oxygen, a main product was benzaldehyde and its G value was 0.87. In the absence of oxygen, the main products of the radiolysis were dibenzyl, benzyl phenylcalbinol and hydrobenzoin, which were regarded as the radicao-reaction products of PhCH2 and PhCHOH, and the yield of benzaldehyde was negligible. Irrespective of the presence of oxygen, o- and p-hhdroxylated products of benzyl alcohol were found only in small quantity.     

丙炔醇/邻苯二甲酸共聚物

本文报导了(Ph_3P)_2·PdCl_2存在下的丙炔醇与邻苯二甲酸的共聚合反应。并通过IR证明了共聚产物是邻苯二甲酸与丙炔醇均聚物的缩合产物。产物电导率说明邻苯二甲酸的加入,并没破坏聚丙炔醇的共轭体系,但共聚物的电导率随邻苯二甲酸含量的增加而降低。邻苯二甲酸的加入,共聚物的表面结构更为致密。产物的热稳定性随邻苯二甲酸含量的增加而提高。     

Acid-catalyzed intramolecular ring-opening reactions of cyclopropanated oxabenzonorbornadienes with alcohol nucleophiles

An investigation of intramolecular ring-opening reactions of various cyclopropanated oxabenzonorbornadienes (CPOBDs) with alcohol nucleophiles is reported, which forms two regioisomeric products in good yields. The effect of various tether lengths was explored, wherein increasing the alcohol tether length to 4 or 5 carbons exclusively generated Type 3 products in good yield, while C-1-hydroxymethyl substituted CPOBD formed a 1,3,5-cycloheptatriene derivative in excellent yield. Electron donating arene and electron withdrawing C-5-bridgehead substituents formed Type 3 major products, whereas electron withdrawing arenes and electron donating C-5 substituents preferentially afforded Type 2 compounds. A mechanism is also proposed for the formation of both regioisomeric products.     

Gas-chromatographic determination of carboxylic acid anhydrides in oxidation products of alcohols and other organic compounds

A procedure was developed for the gas-chromatographic determination of carboxylic acid anhydrides in the composition of oxidation products of organic compounds after their conversion into alkyl formate by formic acid and benzyl alcohol or other primary alcohol introduced into the reaction medium. The reaction proceeds through the mixed anhydride, which is formed in situ from formic acid and the determined anhydride and is predominantly transformed into the corresponding alkyl formate in alcoholysis with alcohol. The potentialities of the procedure were illustrated by the determination of anhydrides in oxidation products of cyclohexane, cyclohexanone, and cyclohexanol.     

Asymmetric aza-Michael reactions catalyzed by cinchona alkaloids

The organocatalysed asymmetric aza-Michael addition of hydrazones to cyclic enones has been achieved in good yield and stereoselection using cheap and commercially available cinchona alkaloids as catalysts. A systematic study of the influence of the structure of the enone on the stereoselectivity was carried out, leading to optically active products with up to 77% ee. The products can be recrystallized to give nearly enantiopure products, and furthermore it was shown that the products could be reduced to the corresponding 1,3-benzylidenehydrazino alcohol derivatives with high diastereoselectivity.     

(2+4)-Cycloaddition with Singlet Oxygen. 17O-lnvestigation of the Reactivity of Furfuryl Alcohol Endoperoxide¶

In earlier work, the use of furfuryl alcohol as a specific singlet oxygen acceptor was proposed because of the high ratio between the rate constants of chemical reaction and physical quenching. In contrast to furfuryl aldehyde, a number of products are formed by this type II photo-oxidation of furfuryl alcohol. These products may be derived from the endoperoxide of furfuryl alcohol as a common intermediate. The present work focuses on the reactivity of this endoperoxide that was marked specifically by the use of ¹⁷O₂ as a source for singlet oxygen. The analyses of the stable products, their yields and their labeling distribution reveal a strong solvent effect on the primary reaction pathways, and nucleophilic substitution reactions leading to hydroperoxide intermediates are dominant.     

Coupled hydroperoxide lyase and alcohol dehydrogenase for selective synthesis of aldehyde or alcohol

The main objective of this work was to improve the selective synthesis of a volatile compound: aldehyde or alcohol using a coupled-enzyme system. A novel method of synthesis of C₆-aldehyde or alcohol was carried out in the presence of hydroperoxide lyase (HPLS) activity coupled to alcohol dehydrogenase (ADH) activity. After cleavage of the initial substrate, hydroperoxy fatty acid catalyzed by HPLS, the second enzyme, ADH, can catalyze the reduction of the aldehyde to the corresponding alcohol, or the oxidation of contaminating alcohol into aldehyde, depending on the cofactor present in the medium (oxidized or reduced form). We succeeded in improving the synthesis of one of the products. When coupling HPLS to NADP, the selectivity of hexanal production from 13-hydroperoxy linoleic acid was improved, and hexanol production was reduced 5 to 10 times after 15 min of reaction at 15 °C and pH 7.0. In another experiment, HPLS was coupled to ADH in the presence of NADH. The production of alcohol (hexenols) was then favored especially when using 13-hydroperoxy linolenic acid as substrate at concentrations >15 mM, reaching 95% of the products. Coupling of the enzymatic reactions (cleavage reduction) not only reduced the number of steps but also allowed us to increase the conversion rate of the initial substrate (hydroperoxy fatty acid). Structures of the compounds produced in this work were confirmed using gas chromatography-mass spectroscopy analysis. Each of these products has its own delicately different fresh odor that can be used in various applications.     

Conversion of Alcohols to Bromides by Trimethylsilane and lithium Bromide in Acetone

Conversion of alcohols to alkyl bromides is one of the most frequently used functional group transformation reactions. Phosphorus tribromide is one of the most popular classical reagents. Triphenylphosphine has been used in combination with bromine,carbon tetrabromide,N-halo imides and other bromide compounds as a mild reagents for the preparation of alkyl bromides. More reacently, halotrimethylsilanes were found to be useful for halogenation of alcohols. Geo- rge A.Olah successfully convert…     

Temperature gradient interaction chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of air terminated polystyryllithium

The reaction products of polystyryllithium with air were characterized by size-exclusion chromatography, temperature gradient interaction chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Polystyryllithium was prepared by anionic polymerization of styrene initiated with sec-butyllithium in cyclohexane under an Ar atmosphere. It was confirmed that polystyryl ketone, polystyryl alcohol, and directly coupled polystyrene were the major products in addition to the normally terminated polystyrene, which is consistent with the results in the literature. We could also identify the presence of methoxy and carboxylic acid end capped polystyrenes as well as dipolystyryl ether as minor products. Among the minor products, dipolystyryl ether has not been reported yet.     

Analysis of tensides in complex samples with comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry

Multidimensional gas-chromatographical analysis of various tensides of natural or synthetic origin in cosmetic products is demonstrated. Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry allows the qualitative and quantitative determination of alkyl polyglucosides (AG), fatty alcohol ethoxylates (FAEO), fatty alcohol sulfates (FAS), fatty alcohol ether sulfates (FAES) and cocamidopropyl betaines (CAPB) in shower gel and cleaning agents. The samples were aliquoted in two parts. The first part was silylated, diluted and analysed; then, in order to detect anionic tensides (FAES, FAS) too, the second aliquot was hydrolysed before being silylated for analysis. Because of their amphoteric character, the betaines can only be analysed by gas chromatography after thermal decomposition in the injector, which leads to the corresponding amidoamines among other products.     

氟改变了醇在镍(100)表面上的氧化机理

利用程序热脱附(TPD)实验研究了2-丙醇和三氟-2-丙醇在Ni(100)表面的吸附和热反应过程. 实验结果表明, 电负性大的氟原子取代丙醇中γ-位氢原子后, 使丙醇从脱氢反应转化为脱水反应. 在这两种化合物的TPD 实验产物中发现, 有以脱水反应生成的烯烃(丙烯, 三氟丙烯), 脱氢反应产生的酮类(丙酮, 三氟丙酮)等分子析出. 实验结果表明, 氟原子取代γ-H后阻止了产生中间产物醇盐的β-H 脱氢反应, 打开了γ-H脱氢反应的通道, 导致烯烃的产生. 在2-丙醇吸附于镍表面的TPD实验中观察到了消去β-H产生丙酮的脱氢反应, 而1,1,1-三氟-2-丙醇在镍表面上经过脱水反应则产生了3,3,3-三氟丙烯.     

Reactions of Carbazoles with Hexacarbonyl Dicobalt Complexes of Propynol and 1,4-Butynediol

Metallopropargylation of a number of carbazoles was performed by dicobalt hexacarbonyl complexes with propargyl alcohol and 1,4-butynediol in the presence of boron trifluoride etherate. It was shown that depending on the substituents position in the carbazole ring occurred either N- of C-propargylation; with 1,4-butynediol formed also oligomeric products.     

Revealing structural effects: electrochemical reactions of butanols on platinum

Spectroelectrochemical studies on the reactivity of butanol isomers on Pt electrodes in perchloric acid medium led to the observation of structural effects that result from the different arrangements of atoms in the organic molecules. The use of differential electrochemical mass spectrometry (DEMS) to detect volatile products showed that all four isomers react on the electrode, though different product yields were observed for each compound. In spite of the differences in the electrochemical behaviour of the butanol isomers, a series of general processes accounts for the results obtained. The formation of strongly adsorbed residues by a dehydration process leading to the formation of a C=C bond was proposed for all isomers. Electroreduction of the adsorbates produces C(4) and C(3) alkanes, and the latter reveal the existence of a fragmentation process. The C(4) hydrocarbons can be formed by hydrogenation of these residues and by hydrogenolysis of alcohol molecules in the bulk solution which react at the electrode with adsorbed hydrogen. On the other hand, CO(2) is formed during electrooxidation of the adsorbed species. Partial-oxidation products containing a carbonyl group were detected from 0.2 M solutions of 1-butanol, isobutyl alcohol and sec-butyl alcohol. The tertiary alcohol tert-butyl alcohol only reacts in its adsorbed state.     

H3PW12O40 and its cesium salts as pentane isomerization catalysts at ambient temperature

The activity of Mg−Al basic heterogeneous catalysts in the reactions of alcohols with ethylene oxide was studied. The kinetics of alcohol oxyethylation was examined. The kinetic equation of the reaction was determined and the structure of products was studied. The distribution coefficients of the oxyethylation reaction products were calculated. A comparison of the catalytic activity of Mg−Al hydroxides and products of their thermal treatment was made.     

Static SIMS studies of fatty alcohols,amines and esters on gold and aluminium–magnesium alloy surfaces

Static secondary ion mass spectrometry was used to study the chemical reactions and lateral distributions of fatty amines, alcohols and esters spin coated onto gold surfaces and commercial aluminium–magnesium (Al–Mg) alloy surfaces, cleaned using UV–ozone. The aim of this study is to develop an understanding of the interactions of model lubricants with metal surfaces, such as gold and aluminium. This static SIMS study of organic thin films has been able to identify specific reaction products on the aluminium surface for each functional group. This work demonstrates that organic molecules with alcohol, ester and amine functional groups undergo specific chemical reactions with oxidized Al–Mg alloy surfaces. For example, films composed of the fatty alcohol dodecanol were observed to emit monomers, dimers and trimers with discrete distributions. In addition, negative secondary ion mass spectra indicate that a surface carboxylate is formed from the alcohol. The formation of carboxylate reaction products was confirmed by Fourier transform infrared spectroscopy. On Al–Mg alloy surfaces, a direct interaction with the amine and aluminium oxide surface is observed by the detection of a molecular ion that corresponds to the mass of dodecylamine and AlO^?, characteristic of aluminium oxide. Ethyl laurate was shown to eliminate the ethyl group, leaving the laurate anion. This study demonstrates the ability of time‐of‐flight (ToF) SIMS to discriminate and detect chemical reaction products formed between model lubricant molecules and metal surfaces. As a result of this study, the use of ToF‐SIMS to identify reaction products of model lubricants can be extended to provide a better understanding of the interactions of lubricants and metal surfaces at high temperatures and pressures that more closely resemble the conditions encountered in industrial rolling processes. Copyright © 2005 John Wiley & Sons, Ltd.