A reaction of 3,4-unsaturated carboxylic acids with paraformaldehyde or 1,3,5-trioxane

3,4-Unsaturated acids were condensed with paraformaldehyde in boiling acetic acid containing a small amount of aluminium chloride to afford 2,3-unsaturated-δ-lactones. For example, from 2-(cyclohexen-1′-yl)caprylic acid (I) and paraformaldehyde, 2′-hydroxymethyl-2-cyclohexylidenecaprylic acid lactone (II) was obtained in up to 93% yield. Several 2,3-unsaturated-δ-valerolactones were obtained in good yield by this new method. These lactones may be used as perfumery materials.     

Extraction of carboxylic acids with neutral extractants

Theoretical Foundations of Chemical Engineering - In the review, the features of the interphase distribution of weak acids (K а < 10–2) in the systems containing neutral...     

Monoethoxylation of hindered carboxylic acids

Polyethoxylates of unhindered fatty acids are well known as surface active agents. The monoethoxylates of these acids, however, are difficult to prepare in good yields. It has now been demonstrated that monoethoxylates of hindered aliphatic acids can be prepared in high selectivity and conversion. Experimental conditions are reported which overcome serious side reactions prevalent with unhindered acids. Presented at the 156th American Chemical Society National Meeting.     

Mechanism of crosslinking of papers with polyfunctional carboxylic acids

Brief thermal curing of papers treated with an aqueous solution of polyfunctional carboxylic acids and NaH₂PO₄ imparts substantial wet strength to the papers. The effectiveness of such carboxylic acids increases with their functionality in the order 1,2,3,4-butanetetracarboxylic acid (BTCA) > tricarballylic acid (TCA) ? succinic acid. The two main stages of the curing reaction of papers, i.e., pendant attachment of the polyfunctional carboxylic acids via esterification with cellulosic hydroxyl groups, and its further reaction with another cellulose hydroxyl group producing crosslinks of the cellulose fibers were analyzed separately using a combination of acid-base and conductometric titrations. The extent of reaction of the polyfunctional carboxylic acids with paper was followed by pH titration, which shows the total decrease in acid functions as the curing progresses and is directly related to the total consumption of carboxylic acids groups by ester attachment and ester crosslinking steps. The conductometric titration, on the other hand, measures the increase in carboxylic acids bound to cellulose units of the paper as a direct result of previous esterification steps. Our studies reveal that the reaction of BTCA with papers is essentially quantitative after 15 min of curing. The amount of once-reacted BTCA increases in the initial phases of the curing reaction and then decreases as more and more carboxylic acid units are converted into crosslinking sites, while the amount of crosslinked BTCA increases throughout the curing reaction. The reaction profile of papers with TCA differs from that of BTCA in that the curing reaction is initially dominated by the formation of ester appendages; crosslinking becomes the main reaction only after extended curing times. We attribute this difference to the ability of BTCA to form an highly reactive difunctional crosslinking reagent at the outset of the curing reaction, while TCA is initially monofunctional in its reaction with cellulosic hydroxyl groups (formation of a monoanhydride). The relationship between the wet tensile strength of the treated papers and their degree of crosslinking is also discussed. © 1995 John Wiley & Sons, Inc.     

Synthesis and characterization of polyanilines doped with several carboxylic acids and with a carboxylic acid equivalent

Polyanilines (PANIs) doped with several organic acids—maleic acid, squaric acid and 2‐propynoic acid—were chemically synthesized in good yields, while PANI doped with 2,6‐dihydroxybenzoic acid did not form under similar polymerization conditions. The resulting PANIs were characterized by spectroscopic and thermal analysis, and it was found that the spectroscopic and thermal properties of these PANIs were affected by the type of dopant ion. Formation of different oxidation states of these PANIs were confirmed by the spectroscopic (UV‐visible and FT‐IR) analysis. Thermogravimetric analysis suggested that PANI doped with maleic acid indicated higher thermal stability than those with the other dopants. The yield and conductivity of PANI doped with maleic acid were found to be higher than those with the other dopants. The PANI doped with 2‐propynoic acid was readily soluble in organic solvents including tetrahydrofuran and dioxane. Copyright © 2005 Society of Chemical Industry     

Extraction of copper from aqueous solutions with carboxylic acids

The distribution equilibrium data at 25°C for the extraction of copper from aqueous solutions, containing sodium nitrate or sodium sulphate, by carboxylic acids using toluene, benzene and carbon tetrachloride as diluents have been measured. The carboxylic acids used are n-myristic, n-lauric and n-capric. The results obtained led to the conclusion that the composition of the extracted species corresponds to (CuR₂.HR)₂, being irrespective of both the nature of organic phase and the aqueous phase. The addition of sodium sulphate, instead of sodium nitrate, decreases the extraction efficiency due to the formation a CuSO₄ ion-pair into the aqueous phase. The diluent effect has been related to the activity of the dimerised carboxylic acid in the diluent.     

The reaction of phosphorus trichloride with fatty acids

An investigation of the reaction of phosphorus trichloride with fatty acids has provided a reliable guide to choice of reaction conditions. Excesses of 25–100% phosphorus trichloride are required for high conversions ; the shorter the chain length of the acid, the larger the excess of reagent required. We consider the reaction path to be satisfactorily established and have shown several hypotheses made to account for the formation of hydrogen chloride as a by-product, to be unnecessary. Two alternative mechanisms for the reaction are proposed and discussed.     

Solid state reaction of bifunctional bicyclo orthoesters and carboxylic acids and their metal adhesive properties

Five kinds of novel bifunctional bicyclo orthoesters (BOEs) were synthesized and copolymerized with multi-functional carboxylic acids, having plural carboxyl and hydroxyl groups, to develop functional materials usable as non-volatile adhesives. In a solid-state reaction of BOEs with the carboxylic acids, mechanical mixing converted the BOE moiety to a corresponding hydrolyzed form via ring-opening and isomerization reactions. The solid-state reaction, requiring moisture and mechanical stress, was accelerated by the higher reactivity given by the α-hydroxyl group in the acids. Superior adhesive bonding to the Ni-Cr alloyed metal substrate was achieved via a heating process at 150 °C, and high average tensile strengths of ∼80 MPa were obtained by using mixtures of BOEs and dl-tartaric acid. This highly adhesive property was achieved not only by polycondensation of BOE-hydrolyzates and the carboxylic acids, but also by polyaddition of BOEs and the carboxylic acids.     

Liquid-crystalline behaviour of some carboxylic acids

Summary A series of 4--carboxyalkoxyphenyl-4-methoxybenzoates 2 has been prepared. Compounds with a spacer length of n=3 and n=5 show liquid crystalline behaviour. The products were characterized by IR and ¹HNMR-spectroscopy, mass spectrometry, optical microscopy and DSC-measurements. The compounds are potentially useful as side-groups in liquid-crystalline polymers.     

不饱和羧酸锌盐对NBR的增强

通过氧化锌与甲基丙烯酸或丙烯酸的中和反应,在丁腈橡胶（ＮＢＲ）生成了甲基丙烯酸锌或丙烯酸锌,研究了过氧化物硫化ＮＢＲ的力学性能和交联结构。结果表明,原位合成法甲基丙烯酸锌或丙焕酸锌增强ＮＢＲ可得到与直接加入法类似的增强效果,硫化胶具有高强度、高硬度和高伸长率;对交联结构的分析表明,硫化胶的良好性能与其含离子交联键有密切关系。     

Reactivity of acrylonitrile-butadiene-styrene terpolymer grafted with long-chain unsaturated carboxylic acids

Reactivity of acrylonitrile-butadiene-styrene terpolymer (ABS) grafted with long-chain carboxylic acids, such as undecylenic acid and oleic acid, was investigated and compared with that of ABS grafted with short-chain carboxylic acids by reacting with dodecylamine, glycidyl methacrylate (GMA), and 2-ethyl-2-oxazoline in solution, and with polyamide (PA) in melt. The overall activation energy of ABS-g-acrylic acid, ABS-g-crotonic acid, ABS-g-undecylenic acid and ABS-g-oleic acid reacting with dodecylamine was 31.2, 16.2, 18.2 and 21.6 kJ/mol, respectively. The overall activation energy of ABS-g-acrylic acid, ABS-g-crotonic acid, ABS-g-undecylenic acid and ABS-g-oleic acid reacting with GMA was 29.0, 31.9, 61.4 and 61.8 kJ/mol, respectively. The stronger the acidity of grafted acid, the higher the percentage of the grafted acid reacted. The overall activation energy of ABS-g-acrylic acid, ABS-g-crotonic acid, ABS-g-undecylenic acid and ABS-g-oleic acid reacting with 2-ethyl-2-oxazoline was 19.5, 20.9, 23.4 and 24.5 kJ/mol, respectively. The lower the steric hindrance and the higher the chain mobility of grafted acid, the higher the percentage of the grafted acid reacted. The reactivity of dodecylamine, GMA and 2-ethyl-2-oxazoline reacting with grafted ABS is: GMA<2-ethyl-2-oxazoline<dodecylamine. The reactivity of grafted polymer is: ABS-g-acrylic acid<ABS-g-crotonic acid<ABS-g-oleic acid<ABS-g-undecylenic acid, when they react with PA in melt.     

Boron-mediated aldol reaction of carboxylic esters

This Account outlines the unique features of the boron-mediated aldol reaction of carboxylic esters, which include (i) facile isomerization of E-enolate to Z-enolate and (ii) formation of a doubly borylated enolate upon enolization of acetate esters. The first carbon-bound boron enolates were spectroscopically characterized, and they appeared to be responsible for these unique properties. Furthermore, complementary anti- and syn-selective boron-mediated asymmetric aldol reactions of chiral propionate esters have been developed. A novel double aldol reaction of acetate esters has been discovered, and a plausible mechanism of the double aldol reaction is proposed.     

Formation and reactions of cluster ions from aromatic carboxylic acids together with amino acids

The cluster formation of several aromatic carboxylic acids, ferulic acid, vanillic acid, sinapinic acid, and 3,4-dihydroxybenzoic acid was investigated by means of laser desorption into a supersonic beam followed by multiphoton ionization-time-of-flight mass spectrometry. The formation of not only homogeneous clusters, but also of heterogeneous clusters with some small amino acids was studied. The different neutral clusters formed in the supersonic expansion were ionized by a multiphoton process employing either nano- or femtosecond laser pulses. Strong differences in the detection of cluster ions due to the laser pulse length employed for multiphoton ionization were observed. Only femtosecond activation led to mass spectra with intense signals of the cluster ions. In addition, in the case of femtosecond ionization, protonated amino acids were detected in the mass spectra. As direct ionization of the free amino acids is not possible under the chosen ionization conditions because they lack an adequate chromophore, these protonated amino acids are assumed to be formed via an intracluster proton transfer in the heterogeneous dimer and subsequent decay of the ionized cluster (dissociative proton transfer). Such well-known processes for heterogeneous clusters consisting of a substituted aromatic molecule and small polar solvent molecules may be involved in the matrixassisted laser desorption ionization (MALDI) process.     

羧酸类配位聚合物的研究进展

羧酸类金属配位聚合物是一种新型功能性分子材料,近年来得到科学家的普遍关注。本文对羧酸类金属配位聚合物的分类进行了综述,综述了羧酸类金属配位聚合物研究的重要性和国内外羧酸类金属配位聚合物的研究工作,对苯多羧酸类、吡啶羧酸类、草酸类、脂肪族二羧酸类配合物在手性拆分和催化、分子磁体、非线性光学方面的研究进行了详细介绍,列举了近年来这类配位聚合物的研究成果和开发进展,并对其发展趋势进行了展望。     

Wet air oxidation of long-chain carboxylic acids

The wet air oxidation of long-chain carboxylic acids has been studied. Caprylic acid and oleic acid were selected for the degradation studies. The effectiveness of the process has been followed in terms of the disappearance of carboxylic acids and in terms of COD removal. The oxidation process was studied in the temperature range 473–573 K with a total pressure of 15 MPa of synthetic air, which means an oxygen excess. The oxidation process was found to be pseudo-first order with respect to the carboxylic acid concentration and the activation energies were 55.5 kJ/mol for caprylic acid and 53.8 kJ/mol for oleic acid. Acetic acid was found to be the main intermediate in the oxidation process and, therefore, a generalized kinetic model based on the formation and elimination of acetic acid has also been applied to the experimental data.     

The quantitative determination of plasmalogen by its reaction with mercuric chloride

The alk-1-enyl group of 1-alk-1¹-enyl-2-acyl-glycerophospholipids (plasmalogens) rapidly combines with mercuric chloride. At 0 C, there was a 1∶1 stoichiometry for Hg binding to the reactive enol group of plasmalogens. Aldehydes were not released, indicating that the alkenyl ether bond was not cleaved. Hg binding to less reactive double bonds in unsaturated fatty acids was not significant. Quantitative estimation of bound Hg afforded a rapid and sensitive assay for alkenylacyl lipids and gave values similar to those obtained with other methods of analysis. The proportion of plasmalogens in bovine myelin glycerophosphatides and in ethanolamine glycerophosphatide was 35 and 75%, respectively. Plasmalogens account for 23.3% of the total glycerophospholipid of rat erythrocytes.