Pyrolysis of cyclo-aromatic diesters

Studies on the pyrolysis of cyclo-aromatic diesters derivatives of 3-phenylprop-2-en-1-ol are presented. The diesters are obtained during catalyzed esterification process of a stoichiometric ratio of 3-phenylprop-2-en-1-ol with suitable cycloaliphatic or aromatic acid anhydride in the solvent-free medium. As an acid anhydrides cyclohexane-1,2-dicarboxylic anhydride, cis-4-cyclohexene-1,2-dicarboxylic anhydride, bicyclo[2.2.1]-5-heptene-2,3-dicarboxylic anhydride, and phthalic anhydride were applied. The thermal properties of obtained compounds under inert atmosphere were tested by means of differential scanning calorimetry and thermogravimetry coupled with FTIR analysis. The pyrolysis products were determined and the probable mechanism of their decomposition was proposed.     

Preparation of diverse BODIPY diesters

The synthesis and properties of a variety of substituted BODIPY diesters is presented. We find that certain substitution patterns afford appreciable yields of the target compounds and that electronic effects result in predicable differential fluorescent behavior. Challenges to further water solubilize these dyes and/or provide new points of attachment for biological tagging remain, these strategies are discussed.     

Synthesis of saturated bicyclic diesters

Bicyclic saturated diesters were synthesized by the catalytic addition of monobasic saturated acids to unsaturated bicyclic esters. A possible mechanism of the reaction was proposed.     

Thermal properties of citronellyl diesters

Thermal properties of linear citronellyl diesters were studied by TG/DSC/FTIR/QMS-coupled method in inert and oxidative atmospheres. The diesters decompose in one main step in inert atmosphere. As main pyrolysis products, the formation of mainly monoterpene hydrocarbons, acid anhydrides, monoacids, cyclic ketones, aldehyde fragments, carbon dioxide, and water was observed. It was indicated on the ester and O-citronellyl bonds cleavage, partial decarboxylation, and elimination of water from formed dicarboxylic acids during their pyrolysis. The decomposition in air runs in two steps. The first step was connected with the creation of monoterpene hydrocarbons, monoacids, cyclic ketones, aldehydes, carbon dioxide, carbon monoxide, and water. In the second step of decomposition, mainly carbon dioxide and water were produced. It was testified to ester and O-citronellyl bonds cleavage, partial oxygenation, and decarboxylation process of the primary formed decomposition products.     

Synthesis of polyamides through active diesters

Polycondensation reactions of active diesters including several aromatic or heterocyclic nuclei with hexamethylenediamine were carried out in order to investigate the enhancement of reactivity of active diesters for nucleophilic replacement to form polyamide for synthesis of polyamides under moderate condition. These active diesters easily induce polycondensation reaction in solutions, forming polyamides at room temperature. Solvents have a considerable influence on the rate of the polycondensation. The reactivity of these active diesters toward aminolysis is strongly controlled by the structure of the alcohol formed. The reactivity enhancement of active ester group toward amine could be attributed either to the polarization of carbonyl group or to the resonance effect of the alkoxy group.     

Synthesis of polyesters from active diesters

Ester-exchange and polycondensation reactions of active diesters such as diphenyl, dithiophenyl, or dipyridinyl esters of adipic or terephthalic acids with glycols were carried out in order to investigate the reactivity of these active diesters toward nucleophilic replacement. Catalysts such as potassium carbonate were required for the esterexchange of these active diesters. Comparison of the reactivity of these active diesters with that of ordinary diesters in the presence of potassium carbonate as a catalyst indicates the rates or the equilibrium constants of the exchange reactions of these active diesters were much larger than those of ordinary diesters, indicating that polyesterification reactions favorably occur. Polyesters were obtained in good yield either by solution or bulk methods in mild conditions.     

Practical selective monohydrolysis of bulky symmetric diesters

The highly efficient selective monohydrolysis reaction we previously reported has been applied to monohydrolysis of several bulkyl symmetric diesters, including diethyl esters, dipropyl esters, and dibutyl esters. A greater proportion of a polar aprotic co-solvent, DMSO, and aqueous KOH appear to help improve the reactivity of bulky diesters compared to the corresponding dimethyl esters. The procedure is mild and practical, yielding the corresponding half-esters in high yields under simple conditions.     

A facile approach to phosphonic acid diesters

The symmetric H‐phosphonates of carbohydrate and other compounds were conveniently prepared by direct transesterification of the corresponding monohydroxylic compounds with diphenyl phosphite. The approach has the merits of mild reaction conditions and high yields. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:208–210, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10130     

X-ray diffraction studies of mesomorphic ferrocene diesters

Abstract

The crystal and molecular structure of 1,l ′-bis(4′-pentyloxybiphenyl)ferrocene dicarboxylate ester (1) has been determined by X-ray diffraction at 295 and 160K. The molecule is found to exist at both temperatures in an extended S geometry. The carboxyl groups are essentially coplanar with the cyclopentadienyl rings but almost perpendicular to the attached phenyl ring. Low angle X-ray diffraction of three diesters in the smectic phases were also studied. The results were not very definitive because of the lack of thermal stability for the monotropic phase behaviour. Nevertheless, the layer spacing of about 47 A for one of the compounds at 409K is consistent with the extended S shape conformation.     

Synthesis of lipophilic diesters of N-acetylmuramoyl-L-alanyl-D-glutamic acid

Lipophilic diesters of N-acetylmuramoyl-L-alanyl-D-glutamic acid have been synthesized from the dipentadecyl, didodecyl, and dioctyl esters of D-glutamic acid.M. V. Frunze Simferopol' State University. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 101–105, January–February, 1991.     

Enzymatic desymmetrization of cis-1,3-cyclohexanedicarboxylic acid diesters

cis-1,3-Cyclohexanedicarboxylic acid (1,3-CHDA) monoesters were prepared in high overall yield and high enantiomeric purity using a three step process from cis/trans-1,3-CHDA. The asymmetry is induced by an enzymatic hydrolytic desymmetrization of a meso cis-1,3-CHDA diester. A judicious choice of ester substituents and enzyme can provide >80% overall yield of either enantiomer in >94% ee.     

Aggregation of deuteroporphyrin IX diesters in aqueous-organic binary solution

The aggregation properties of a series of deuteroporphyrin IX diesters in the THF-Buffer (0.1 mol L-1 Tris-HCl) aquiorgano solvent have been studied by means of UV-Vis and fluorescence spectrometers.Experimental data show that the dimerization of porphyrins is mainly determined by π-πinteraction in pure organic solution while further aggregation of porphyrins with long hydrocarbon chains is more likely driven by hydrophobic-lipophilic interaction in aqueous-organic binary solution.The appearance of the aggregates induces a red shift in absorption spectra and fluorescence quenching in fluorescence spectra.The chain-length effect and chain-foldability effect have also been observed.     

Synthesis of bicyclic and allyl diesters of oxalic acid

An effective synthesis of mixed, bicyclic, and allyl diesters of oxalic acid. The procedure involves addition of oxalic acid to bicycloheptene hydrocarbons followed by esterification of the resulting monoesters with allyl alcohol. The synthesized diesters are new reactive monomers for the synthesis of high-molecular and other organic compounds.     

Calorimetric study of the proximity effect in aliphatic diesters

Excess molar enthalpies,H ^E , at atmospheric pressure and 303.15 K are reported for binary mixtures of 1-chlorohexane with diethyl oxalate, diethyl malonate, diethyl succinate, diethyl glutarate, diethyl adipate, diethyl pimelate and diethyl sebacate. These experimental results, together with those obtained previously on the excess enthalpies of aliphatic diester+n-hexane mixtures, are interpreted in terms of molecular surface interactions between aliphatic, chlorinated and carboxylate groups. Comparison of the enthalpy interchange parameters reveals a decrease of the intermolecular interactions with decreasing intramolecular COO-COO distance in the diester molecule.

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Zusammenfassung Bei Atmosphärendruck und 303,15 K gemessene molare Überschußenthalpien (H ^E werden für binäre Gemische von 1-Chlorhexan mit Diäthyloxalat, Diäthylmalonat, Diäthylsuccinat, Diäthylglutarat, Diäthyladipat, Diäthylpimelat bzw. Diäthylsebacat angegeben. Diese experimentellen Ergebnisse werden zusammen mit den früher für Gemische von aliphatischen Diestern und n-Hexan erhaltenen Resultaten als molekulare Oberflächenwechselwirkungen zwischen aliphatischen, chlorierten und Carboxylatgruppen interpretiert. Ein Vergleich der Enthalpieaustauschparameter läßt eine Verminderung der intermolekularen Wechselwirkungen mit abnehmendem intramolekularem Abstand zwischen den COO-Gruppen erkennen.

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(H ^E ) 303,15 K 1- , , , , , . , + -, , . COO-COO .

     

Flow injection determination of diesters as ferric hydroxamate complexes

Diesters such as succinylcholine chloride (SCC) and dioctylsulfosuccinate (DOSS) can be converted to hydroxamic acids which are found to react with Fe³⁺ in methanol to form a purple chelate complex having an useful absorption band at 520 nm with a molar absorptivity of about 171 L/mole*cm, and a detection limit of 1.5 × 10^–4 M. To adapt this method for flow injection, a methanol-water solvent and acidification of the sample were required to reduce the large blank peak. The reproducibility of the flow injection method was a factor of two better than standard spectrophotometry but the detection limit of the former method was two times higher. This colorimetric method can permit analysis of pharmaceutical products containing either SCC or DOSS. Phosphatidylcholine (lecithin) can also be determined using this method.     

Lewis acid promoted cyclization of enyne triesters and diesters

Reactions of enynes with three or two ester groups (1-4) in the presence of halogen-ligand Lewis acids gave cyclized products with halide incorporation (5-8) with high generality. The cyclization process was also analyzed in a theoretical study. Facile isomerization and dehydrohalogenation of five-membered products 5 and 8 by Al(2)O(3) or Et(3)N were also observed; this process introduces conjugated moieties into the products.