Reaction of lithium naphthalene with carboxylic acids containing the dichlorocyclopropane ring system

Carboxylic acids containing the dichlorocyclopropane ring system react with lithium naphthalene to give dechlorinated products. For example, from the reaction of 9,10-dichloromethylene octadecanoic acid and lithium naphthalene, a mixture of 9,10-nonadecadienoic acid as a main product and unidentified minor products were obtained.     

New catalysts for urea formation reactions. II. Catalytic activity of carboxylic acids

Carboxylic acids with weak acidities showed large catalytic activity. For instance, for chlorine-substituted acetic acid the activity increased with decreasing chlorine content. For benzoic acid derivatives, electron acceptor substituents, such as NO₂, CI, and OH, lowered the catalytic activity, while electron donor substituents such as alkyl and alkoxy groups increased it. Detailed study on the cure rate of polyureaurethane, with 2-methyl benzoic acid as a catalyst, showed that pot life (PL) and the minimum demolding time (DT) had a correlation with the catalyst amount [X] represented by the following equation: where A and B are constants. Further, use of appropriate amounts of the catalyst enhanced tensile strength at break for polyureaurethane.     

Urethane foams from animal fats. II. Reaction of propylene oxide with fatty acids

Propylene oxide has been reacted with 9,10-dihydroxystearic acid to form polyol components for urethane foams. The alkali-catalyzed reaction proceeds slowly until the first mole of propylene oxide is absorbed and thereafter at a higher rate. For other substrates, the initial reaction proceeds most readily with alcohols and decreases in speed with increasing acidity of the hydroxyl group. Threo-anderythro-9,10-dihydroxystearic acids were reacted with approximately 1, 2, 4, 6 and 8 moles of propylene oxide. Both series of the resulting polyols were liquid, unlike corresponding oxyethylated derivatives, which were solids in theerythro series. A small amount of unsaturation was observed in the reaction products in accord with previous studies. The liquid polyols can be used conveniently in the preparation of rigid urethane foams.     

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...     

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     

Membrane transport of organics. II. Permeation of some carboxylic acids through strongly basic polymer membrane

The permeability characteristics of the strongly basic polymer membrane Neosepta® AFN‐7, (Tokuyama Soda) have been studied for acetic, propionic, lactic, tartaric, oxalic, and citric acid. The results were interpreted by using the model of transport in reactive membranes. The specific constants, that is, the maximum flux J_max, the reactivity constant K, and the permeability coefficient (P), were calculated using the experimental quasi‐stationary fluxes and the equation derived as a sum of reaction–diffusion (Michaelis–Menten‐type), and the solution–diffusion transport equation. The constants K and J_max were found to range from 0.1 to 5 dm³ mol⁻¹ and from 0.4 × 10⁻⁷ to 2.5 × 10⁻⁷ mol cm⁻² s⁻¹ depending, on the acid properties. The values of K and J_max were correlated with the dissociation constants K_dis.acid, and the diffusion coefficients D_aq.acid in aqueous media, respectively. It was found that the reaction–diffusion flux is predominating for all acids, except for the lactic one, when the feed concentration is lower than 0.5 mol dm⁻³. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2179–2190, 1999     

Copolymers of N-vinylcarbazole with monomers containing carboxylic acid groups or carboxylic anhydride groups. II. Photoconductivity and composition

Copolymers of N-vinylcarbazole containing olefinic monomers that possess carboxylic acid or anhydride functionality have been produced. The photoconductive properties of the copolymers were measured. Fluorimetry has been used to relate this photoconductivity to the copolymer composition. Photoconductivity was greatest in copolymers containing high percentages of vinylcarbazole. It is suggested that this is due to block copolymer formation, since the development of such blocks allows greater interchromophore overlap than would be possible with alternating copolymers, which exhibit low photoconductivity.     

The reaction of carboxylic acids with vinylmagnesium chloride

The reaction of vinylmagnesium chloride with an aromatic carboxylic acid gives a vinyl ketone. From benzoic acid, 5-oxo-5-phenyl-1-pentene is obtained. Similarly, from aliphatic carboxylic acid, a mixture of vinyl ketone and divinyl carbinol is obtained. From pentanoic acid, a mixture of butyl divinyl carbinol and 5-oxo-1-nonene is obtained.     

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.     

Catalytic Reactions of Guaiacol: Reaction Network and Evidence of Oxygen Removal in Reactions with Hydrogen

Abstract  

The conversion of guaiacol, a prototypical compound representative of lignin-derived pyrolysis bio-oils, was catalyzed by Pt/Al₂O₃ in the presence of H₂ at 573 K. The conversion took place with a high selectivity for aromatic carbon–oxygen bond cleavage relative to the accompanying methyl group transfer reactions. This oxygen removal was not observed in the absence of H₂ as a co-reactant. Products that were formed by methyl-group transfer match those produced in the conversion catalyzed by zeolite HY, which was not active for oxygen removal reactions.     

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.     

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.     

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.     

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。     

Reactions of Substituted Hydroxybenzofurans. II

Bromination of 6-methoxy-2,3-diphenylbenzofuran 1 b leads to the 5-bromo derivative 5 a , whereas 5-methoxy-2,3-diphenylbenzofuran 3b yields the 4,6-dibromo derivative 4b . Nitration of 5-hydroxy-2,3-diphenylbenzofuran 3a gave 6-nitro-5-hydroxy-2-(p-nitrophenyl)-3-phenylbenzofuran 8a . On the other hand, nitration of 3 b yields the mononitro derivative, namely the 5-nitro compound 5 b . Bromination of 10a yields the 4-bromo derivative 10 b . Oxidation of 5a, 4b, 8a, 10a, 5b and 10 b followed by hydrolysis gives the benzophenone derivatives 6c, 7b, 9b, 9b, 6f and 7c , respectively. Both 5 b and 10a were reduced to the corresponding amino derivatives.     

Reactions of antimalarial peroxides with each of leucomethylene blue and dihydroflavins: flavin reductase and the cofactor model exemplified

Flavin adenine dinucleotide (FAD) is reduced by NADPH-E.?coli flavin reductase (Fre) to FADH(2) in aqueous buffer at pH?7.4 under argon. Under the same conditions, FADH(2) in turn cleanly reduces the antimalarial drug methylene blue (MB) to leucomethylene blue. The latter is rapidly re-oxidized by artemisinins, thus supporting the proposal that MB exerts its antimalarial activity, and synergizes the antimalarial action of artemisinins, by interfering with redox cycling involving NADPH reduction of flavin cofactors in parasite flavin disulfide reductases. Direct treatment of the FADH(2) generated from NADPH-Fre-FAD by artemisinins and antimalaria-active tetraoxane and trioxolane structural analogues under physiological conditions at pH?7.4 results in rapid reduction of the artemisinins, and efficient conversion of the peroxide structural analogues into ketone products. Comparison of the relative rates of FADH(2) oxidation indicate optimal activity for the trioxolane. Therefore, the rate of intraparastic redox perturbation will be greatest for the trioxolane, and this may be significant in relation to its enhanced in?vitro antimalarial activities. (1)H?NMR spectroscopic studies using the BNAH-riboflavin (RF) model system indicate that the tetraoxane is capable of using both peroxide units in oxidizing the RFH(2) generated in?situ. Use of the NADPH-Fre-FAD catalytic system in the presence of artemisinin or tetraoxane confirms that the latter, in contrast to artemisinin, consumes two reducing equivalents of NADPH. None of the processes described herein requires the presence of ferrous iron. Ferric iron, given its propensity to oxidize reduced flavin cofactors, may play a role in enhancing oxidative stress within the malaria parasite, without requiring interaction with artemisinins or peroxide analogues. The NADPH-Fre-FAD system serves as a convenient mimic of flavin disulfide reductases that maintain redox homeostasis in the malaria parasite.     

Partially dehydrochlorinated PVC. II. Reactions with dienophiles and hydroxylating agents

Samples of poly(vinylchloride) containing polyene sequences were made by partial dehydrochlorination by alkali in tetrahydrofuran solution, by alkali in dioxane, and thermally in dimethyl-formamide. The reactions of polyene PVC were followed by UV spectrophotometry. Dienophiles were found to have relative reactivities similar to those found in reactions with low molecular-weight dienes. The reaction with maleic anhydride yielded polymers which after hydrolysis contained carboxyl groups. Hydroxylation was made with osmium tetraoxide and performic acid. With the latter reagent the reaction proceeded to complete disappearance of the UV-absorption peaks from trienes and higher polyenes: Gel permeation chromatography analysis showed that hydroxylation could be made with only minor changes in molecular-weight distribution. The formation of gel upon thermal dehydrochlorination in DMF was shown to be due to physical cross linking probably arising by crystallization of polyene segments. The adhesion of the hydroxylated and carboxylated polymers to glass and stainless-steel surfaces was investigated. Films adhered stronger as the degree of dehydrochlorination of the polyene PVC used to make the derivative increased. Samples with long sequences adhered much stronger than those containing short sequences of corresponding degrees of total substitution.