Thermodynamics of inclusion complex formation of hydroxypropylated α- and β-cyclodextrins with aminobenzoic acids in water

Calorimetry, densimetry, ¹H NMR and UV–vis spectroscopy were used to characterize inclusion complex formation of hydroxypropylated α- and β-cyclodextrins with meta- and para-aminobenzoic acids in aqueous solutions at 298.15 K. Formation of more stable inclusion complexes between para-aminobenzoic acid and cyclodextrins was observed. The binding of aminobenzoic acids with hydroxypropyl-α-cyclodextrin was found to be enthalpy-governed owing to the prevalence of van der Waals interactions and possible H-binding. Complex formation of hydroxypropyl-β-cyclodextrin with both acids is mainly entropy driven. The increased entropy contribution observed in this case is determined by dehydration of solutes occurring during the revealed deeper insertion of aminobenzoic acids into the cavity of hydroxypropyl-β-cyclodextrin. By comparing complex formation of aminobenzoic acids with native and substituted cyclodextrins it was found that the availability of hydroxypropyl groups slightly influenced the thermodynamic parameters and did not change the binding mode or driving forces of interaction.     

金纳米修饰毛细管电泳分离氨基苯甲酸

报道了一种金纳米修饰毛细管电泳分离、测定氨基苯甲酸的新方法。采用制备的金纳米进行了石英毛细管修饰。探讨了修饰金纳米浓度、修饰时间以及缓冲溶液加入一定浓度的金纳米对三种氨基苯甲酸分离和测定的影响,优化了分离电压、酸度以及缓冲溶液浓度等实验条件。结果表明金纳米的存在,显著的改进了氨基苯甲酸分离的选择性,增强了分离效率。在优化的实验条件下,进行了邻、间、对三种氨基苯甲酸的分离和测定。线性浓度范围为0.5–40 µg·mL,相关系数0.9978-0.9992。检测限(S/N = 3) 为0.1-0.5µg·mL。     

The use of formamidine protection for the derivatization of aminobenzoic acids

N,N-Dimethylformamidine and novel N,N-diisopropylformamidine protecting groups were used to carry out a one-pot conversion of aminobenzoic acids into the corresponding amides. General conditions for an in situ transformation of aminobenzoic acids and their heterocyclic analogues into the corresponding formamidine-protected acid chlorides were developed. These chlorides were used in reactions with amines, including poorly reactive anilines. The protected amides were then smoothly deprotected by heating with ethylenediamine derivatives, resulting in a general procedure for the one-pot transformation of aminobenzoic acids into their amides. Our one-pot procedure was successfully applied to the preparation of several compounds of pharmaceutical interest.     

Synthesis of β-amino ketones derived from aminobenzoic acids

Russian Journal of General Chemistry - Alkylation of aminobenzoic acids and their derivatives with 3-diethylamino-1-arylpropan-1-one hydrochlorides gave the corresponding β-aminopropiophenones...     

Inclusion complex formation of α- and β-cyclodextrins with aminobenzoic acids in aqueous solution studied by 1H NMR

Complex formation of α- and β-cyclodextrins with para- and meta-aminobenzoic acids in water at 298.15 K was studied by ¹H NMR. The formation of 1:1 inclusion complexes in all systems under consideration was observed. Stability constants of the complexes and chemical shift difference induced by 100% complex formation were calculated. The obtained results were discussed in terms of influence of the cyclodextrin cavity size and position of the side amino group in the aromatic ring of aminobenzoic acid molecule on the binding mode and the complex stability.     

Comparative study of 2‐amino and 3‐aminobenzoic acid copolymerization with aniline synthesis and copolymer properties

Polyanilines soluble in an aqueous basic medium were synthesised by copolymerization of aniline (ANI) with both 2 and 3‐aminobenzoic acids (ABA). Different composition copolymers were prepared by varying the ANI/ABA feed ratio. Poly(aniline‐co‐2‐aminobenzoic acid) (PANI2ABA) and poly(aniline‐co‐3‐aminobenzoic acid) (PANI3ABA) displayed differences in their properties, such as specific charge and fluorescence behavior because the reactivity of 2‐aminobenzoic (2ABA) and 3‐aminobenzoic (3ABA) acids are very different. The new materials were characterized by X‐ray photoelectron, Fourier transform infrared, and Raman spectroscopies. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5587–5599, 2004     

Determination of Aminobenzoic Acids by Extraction with a Hydrophilic Solvent Followed by the Non-Aqueous Titration of the Concentrate

The extraction of aminobenzoic acids with hydrophilic solvents (butyl alcohols, acetone, ethyl acetate) from aqueous solutions was studied. Extraction conditions were optimized using methods of experimental design. A method was developed for the selective determination of acids with the non-aqueous titration of the extract.     

Kinetics of glycine arenesulfonylation in the water-propan-2-ol system

The kinetics of the glycine N-acylation with 3-nitrobenzenesulfonyl chloride in the water-propan-2-ol mixture containing 40–80 wt% water was studied at 298 K. In going from the mixture containing 40% water to that containing 80% water, the arenesulfonylation rate constant increases by a factor of 40. Glycine is considerably more reactive in the arenesulfonylation than aminobenzoic acids.     

Analysis of aminobenzoic acids in waste water from a former ammunition plant with HPLC and combined diode array and fluorescence detection

 Aminobenzoic acids are of major interest in clinical analysis, but their determination in environmental samples has been rarely done. Therefore a method for the determination of 10 aminobenzoic acids in water has been developed, using high-performance liquid chromatography with combined diode array and fluorescence detection. A separation of the analytes has been achieved with a buffer pH 3/methanol gradient. The general elution order has been m-substituted<p-subst.<o-subst. aminobenzoic acids. UV and fluorescence data are presented. In a highly polluted water sample of the former ammunition plant Stadtallendorf/Hessen, 4-aminobenzoic acid, 2-amino- benzoic acid and 2-amino-4-nitrobenzoic acid have been detected. After passing a charcoal filter, only the concentration of 4-aminobenzoic acid in a sample from the same site has been above the detection limit. Besides the ten analytes investigated, several unknown compounds have been present in the samples. Received: 15 January 1996/Accepted 20 February 1996     

Analysis of aminobenzoic acids in waste water from a former ammunition plant with HPLC and combined diode array and fluorescence detection

 Aminobenzoic acids are of major interest in clinical analysis, but their determination in environmental samples has been rarely done. Therefore a method for the determination of 10 aminobenzoic acids in water has been developed, using high-performance liquid chromatography with combined diode array and fluorescence detection. A separation of the analytes has been achieved with a buffer pH 3/methanol gradient. The general elution order has been m-substituted<p-subst.<o-subst. aminobenzoic acids. UV and fluorescence data are presented. In a highly polluted water sample of the former ammunition plant Stadtallendorf/Hessen, 4-aminobenzoic acid, 2-amino- benzoic acid and 2-amino-4-nitrobenzoic acid have been detected. After passing a charcoal filter, only the concentration of 4-aminobenzoic acid in a sample from the same site has been above the detection limit. Besides the ten analytes investigated, several unknown compounds have been present in the samples. Received: 15 January 1996/Accepted 20 February 1996     

Turbidimetric Titration of Ethyl Acetate Extracts of Halo- and Aminobenzoic Acids

The extraction of halo- and aminobenzoic acids from aqueous solutions with a hydrophilic solvent (ethyl acetate) was studied. Conditions for turbidimetric titration of these acids in the organic extract were optimized. Procedures for reliable nonaqueous titration of acids were developed.     

Solid-phase extraction of aminobenzoic acids and aminotoluenesulfonic acids with graphitized carbon black

The extraction of amphoteric aromatic amines from water samples is difficult because of their high polarity. For the enrichment of aminobenzoic acids and aminotoluenesulfonic acids with solid-phase extraction, graphitized carbon black (GCB) was investigated. With few exceptions, the 12 analytes studied were extracted with recoveries > 60% at neutral or basic pH, whereas at pH 3 low recoveries were obtained. Addition of salt caused a decrease of about 50% in recoveries, addition of standard humic acid a decrease of about 20%. The capacity of GCB cartridges was determined with the breakthrough volume for 4-aminobenzoic acid at different concentrations to be 0.5–1% (w/w).     

Titrimetric determination of aminobenzoic acids via lodination

A simple, rapid, and accurate titrimetric method for determination of 50–2000 μg of o-, m-, or p-aminobenzoic acid is developed. The method is based on iodination of these compounds. The resulting iodide, after removal of excess iodine, is oxidized with bromine to iodate which is determined by the Leipert amplification procedure. The recoveries range from 96.8–99.8% and the coefficients of variation do not exceed 0.9% for above 500 μg of aminobenzoic acid, but they increase to 1.5% at the 50 μg level.     

New poly(amide-imide)s syntheses. II. Soluble poly(amide-imide)s derived from 2,5-bis(4-aminophenyl)-3,4-diphenylthiophene and various N-(ω-carboxyalkyl)-trimellitimides,N-(carboxyphenyl)trimellitimides,or N,N″-bis(ω-carboxyalkyl)pyromellitimides

Various dicarboxylic acids with preformed imide rings were readily obtained by the condensation of ω-amino acids and aminobenzoic acids with trimellitic anhydride, and omega;-amino acids with pyromellitic dianhydride. New tetraphenylthiophene-containing poly(amide-imide)s having inherent viscosities of 0.58-1.54 dL/g were prepared by the direct polycondensation reaction of 2,5-bis(4-aminophenyl)-3,4-diphenylthiophene with the imide-containing dicarboxylic acids using triphenyl phosphite and pyridine as condensing agents. These polymers were amorphous and readily soluble in a variety of solvents such as dimethylacetamide (DMAc), dimethylformamide (DMF), and N-methyl–2-pyrrolidone (NMP), and could be easily solution cast into transparent, flexible, and tough films. Most of the poly(amide-imide)s showed clear glass transition on the heating traces of differential scanning calorimetry (DSC) in the range of 146–244°C. Almost all the poly(amide-imide)s exhibited no appreciable decomposition below 400°C, with 10% weight loss being recorded above 420°C in nitrogen. © 1992 John Wiley & Sons, Inc.     

Synthesis of Diels–Alder adducts of N-arylmaleimides by a multicomponent reaction between maleic anhydride, dienes, and anilines

Abstract  

We have carried out the synthesis and characterization of some hexahydroisoindolyl benzoic acids and their corresponding ethyl esters by a multicomponent reaction (MCR) between aminobenzoic acids or aminobenzoates, maleic anhydride, and isoprene in the absence of catalysts. According to additional experiments, the MCR takes place by sequential formation of N-arylmaleamic acids from the aminobenzoic acids or aminobenzoates and maleic anhydride, Diels–Alder adducts of the acids and isoprene, and finally the imides. The ¹H NMR data (coupling constants) of the adducts suggested that the preferred conformation of the corresponding cyclohexene rings is a syn-boat, a fact supported by a density functional theory (DFT) conformational analysis and DFT calculations of the spin–spin coupling constants of the corresponding conformers. Our MCR synthetic methodology was tested successfully in the synthesis of other adducts, for which cyclopentadiene and other anilines were employed.     

Synthesis of benzoic acids and polybenzamides containing tertiary alkylamino functionality

The high-yielding and easily scalable synthesis of a number of benzoic acids bearing a tertiary alkylamino functionality has been achieved. The flexible synthesis began from readily available aminobenzoic acids or terephthaloyl chloride and requires almost no chromatography. Coupling of the synthesised amino acids to a range of substituted anilines was achieved when utilizing a specific combination of DIC, HOBt and DMAP.     

Reaction of functionalized anilines with dimethyl carbonate over NaY faujasite. 3. chemoselectivity toward mono-N-methylation

In the presence of NaY faujasite, dimethyl carbonate (MeOCO(2)Me, DMC) is a highly chemoselective methylating agent of functionalized anilines such as aminophenols (1), aminobenzyl alcohols (2), aminobenzoic acids (3), and aminobenzamides (4). The reaction proceeds with the exclusive formation of N-methylanilines without any concurrent O-methylation or N-/O-methoxy carbonylation side processes. Particularly, only mono-N-methyl derivatives [XC(6)H(4)NHMe, X = o-, m-, and p-OH; o- and p-CH(2)OH; o- and p-CO(2)H; o- and p-CONH(2)] are obtained with selectivity up to 99% and isolated yields of 74-99%. DMC, which usually promotes methylations only at T > 120 degrees C, is activated by the zeolite catalyst and it reacts with compounds 1, 2, and 4, at 90 degrees C. Aminobenzoic acids (3) require a higher reaction temperature (> or =130 degrees C).     

The Reactions of Ortho Aminobenzoic Acids with Gold's Reagent: A Two Atom Lynch Pin Transformation

A series of ortho aminobenzoic acids were treated with Gold's reagent. In each case a 4-hydroxyquinazoline was produced. The resulting transformation constitutes the use of Gold's reagent as a two atom lynch pin.     

Partial molar volumes of organic solutes in water. VII. o- and p-Aminobenzoic acids at T = 298 K to 498 K and o-diaminobenzene atT = 298 K to 573 K and pressures up to 30 MPa

Density data for dilute aqueous solutions of two isomeric aminobenzoic acids and of o -diaminobenzene (1,2-diaminobenzene) are presented together with partial molar volumes calculated from the experimental data. The measurements were performed at temperatures from 298.15 K up to either 498.15 K (aminobenzoic acids) or 573.15 K ( o -diaminobenzene) and at either atmospheric pressure, or at pressures close to the saturated vapour pressure of water, and also at pressure p =  30 MPa. The data were obtained using either a high-temperature and high-pressure flow vibrating-tube densimeter for measurements at elevated pressures or a commercial vibrating-tube cell DMA 602HT for measurements at atmospheric pressure.     

Methyl-and ethyl carbonates derived from vanillin and vanillal in the synthesis of nitrogen-containing compounds

Reactions of 4-hydroxy-3-methoxybenzaldehyde and 3-ethoxy-4-hydroxybenzaldehyde with methyl and ethyl chloroformates in the presence of pyridine gave the corresponding methyl and ethyl carbonates which were brought into condensation with biphenyl-4-amine, naphthalen-1-and-2-amines, and 3-and 4-aminobenzoic acids to obtain the corresponding Schiff bases. Alkyl 4-(9,9-dimethyl-11-oxo-7,8,9,10,11,12-hexahydrobenzo[a]acridin-12-yl)-2-alkoxyphenyl carbonates were selectively synthesized by cascade heterocyclization of naphthalen-2-amine, 5,5-dimethylcyclohexane-1,3-dione, and 4-formyl-2-methoxy(or ethoxy)phenyl methyl(or ethyl) carbonates. Ammonium salts were obtained from the benzoacridine derivatives and Schiff bases derived from aminobenzoic acids.