Unsaturated Diacids Research Articles

Methanolysis of bark suberins: analysis of glycerol and acid monomers

The depolymerization and subsequent analysis of cork suberins from the outer barks of Pseudotsuga menziesii and Quercus suber was performed using a simplified methanolysis procedure. The amount of sodium methoxide catalyst was maintained at 20–30 mM and the methanolysis mixture was submitted to trimethylsilyl derivatisation and used directly for gas chromatographic analysis, allowing simultaneous quantification of glycerol and long-chain monomers. Response factors for glycerol, ferulic acid and one saturated homologue representing each of the suberinic families (i.e. the 1-alkanols, 1-alkanoic acids, ω-hydroxyacids and α,ω-diacids) were determined. Effective depolymerization of suberin was checked using the infrared specta of the residues after methanolysis. Glycerol is a major constituent of the suberins from P. menziesii (26% of total) and from Q. suber (14%). In both suberins, α,ω-diacids are dominant, i.e. 54% of the long-chain monomers in P. menziesii (mostly saturated C16-C22 homologues and the C18 unsaturated diacid), and 53% in Q. suber (mostly the C18 unsaturated diacid and mid-chain oxygenated (epoxide and vic-diol) derivatives). In P. menziesii epoxyacids are absent. The importance of glycerol and α,ω-diacids as suberin monomers supports a polymeric structure based on their successive esterification. Copyright © 2000 John Wiley & Sons, Ltd.

Electrospray mass spectrometry study of selective complexes of polyammonium macrotricyclic ligands with dicarboxylic acids

The complexation of anionic species plays a very important role in chemical and biological processes. Macrocyclic and macropolycyclic polyammonium host molecules have been shown to complex a variety of inorganic and organic anions strongly and selectively. The selectivity of the complexation depends on the substrate length and on the size of the host cavity of the macrocycle. Several methods can be used to characterize the complex formation. We describe here the analysis of the complexation of dicarboxylic acid substrates (HCO2–(CH2)n–CO2H) by a macrotricyclic host using electrospray mass spectrometry. The soft ionization conditions of the electrospray source allow one to maintain, the gas phase, the interactions between the diacids and the ligand. The influence of dicarboxylic acid size (n = 0–6) on the complexation extent, the effect of the pH of the solution on the charge state of the ions and their relative stability towards dissociation induced by collisions, are analysed. In the case of unsaturated diacids, total selectivity was found in favour of the cis vs. the trans isomer. © 1997 John Wiley & Sons, Ltd.

Dibenzo[18]annulenes Incorporating Two Diphenylhexatriene Units

AbstractThe [6.6]cyclophanehexaene hydrocarbon 6a and the dimethoxy[6.6]cyclophanehexaene 6b are prepared starting with the unsaturated diacid 1. An X‐ray analysis of 6a exhibits a planar molecular skeleton. NMR and optical data prove a not fully conjugated macrocyclic π system and its division into two largely separate chromophores.

Patterns of mono- and difunctional carboxylic acids in hydrothermal leachates of humified soil organic matter and peat: geological and environmental implications

Maturation dependent generation of C 1-C 5 mono- and dicarboxylic acids is investigated by hydrous pyrolysis of soil and peat humates. Evolution and extinction patterns of acid populations released during progressive thermal maturing of these humates are examined. Abundant carboxylic acids yields were obtained and two types of carboxylic acid assemblages were identified: an immature acid assemblage, characterised by an abundant C 2-C 4 diacid component and a mature acid assemblage which is nearly devoid of these acids, except for the C 4 diacid. C 1-C 5 monoacids are abundant in both types of acid assenblages, however acid populations characterised by a n-C 4/ i-C 4 monoacid ratio greater than 3.0 and enriched in C 5 monoacids may also indicate a mature acid population. The trans and cis forms of the C 4 unsaturated diacid may also prove useful in defining these assemblages. Geologically these different assemblages imply that the composition of sediment expelled carboxylic acids in the subsurface environment may depend on the timing of expulsion and thermal maturity of the source rock. The abundant production of these acids from humates also implies that where industrial activities involve heating of soil or rock organic matter, waste carboxylic acid effluents may cause industrial and environmental problems.

Poly(ether urethane amide)s: A new family of biomedical elastomers

Poly(ether urethane amide)s (PEUAm), have been synthesized by chain extending macrodiisocyanates with dicarboxylic acids. A series of aliphatic, saturated and unsaturated diacids were incorporated into the polymeric backbone. Their length and molecular symmetry largely affected the hard block crystallizability and the morphology of the PEUAm matrices. When the polymer was chain extended with fumaric acid (PEUFA) or maleic acid (PEUMA), double bond-containing hard domains were generated. Due to the enhanced symmetry associated with its trans conformation, the fumaric acid created crystalline, better organized hard domains. These reactive double bonds performed as anchoring sites for further derivatization of these polymers. By grafting HEMA, a variety of polyurethane based matrices were obtained, covering a wide range of mechanical properties and water uptake levels. Amine-terminated PEG chains were successfully grafted onto the polyurethane backbone, derivatizing the polymer with a molecule of biological relevance.

Water sorption in styrene crosslinked polyesters

AbstractVarious polyester samples differing essentially by the diol nature, the proportion of unsaturated diacid, or the prepolymer chain length were studied by gravimetry at 30, 40, or 50°C, 95% RH. The water equilibrium concentration increases with the test temperature and with the polar group concentration: esters, ethers and alcoholic or acidic chain ends. The diffusivity appears as an increasing function of the crosslink density which can be due to the “bonding” effect of chain ends through strong hydrogen bonds and/or to the fact that local motions are as favoured as the chain end concentration decreases.

ChemInform Abstract: Synthesis of 2,3‐Methanoglutamic and ‐pyroglutamic Acid.

AbstractReaction of the unsaturated diacid (I) with diazomethane (II) gives the pyrazoline (III) which is cleaved upon photolysis, producing the cyclopropane (IV).

Investigation of the reaction of some unsaturated dicarboxylic acid anhydrides with cyclic carbonates

Abstract This work reports attempts to extend to unsaturated anhydrides the rapid reaction of dicarboxylic acid anhydrides with ethylene carbonate to form polymer directly. The reaction of unsaturated diacid anhydrides with two cyclic carbonates, ethylene and propylene carbonate, leads to gelled products whenever the anhydride is capable of Michael addition, while an anhydride without such unsaturation gave linear polymer in- stead. The GC/MS results, along with efforts to trap radical reactions, support Michael addition as an explanation of gelation in these systems.

ChemInform Abstract: Bislactonizations of Olefinic Diacids with (Hydroxy(Tosyloxy)iodo)benzene.

AbstractThe cyclic (I) or acyclic unsaturated diacids (IV) are converted into the bislactons (III) and (V) respectively by treatment with the iodobenzene (II).

Processable heat‐resistant polymers, 10. Synthesis and characterization of an unsaturated polyesterimide containing 1,5‐dioxoisoindoline‐2,5‐diyl units

AbstractA new polyesterimide containg CC‐double bonds was prepared by reacting an unsaturated diacid chloride containing a cyclic imido group with ethylene glycol at low temperature. The solubility, thermal, electrical and cross‐linking properties of the polymer were studied. The polymer was found to be thermostable and soluble in highly polar solvents. X‐ray diffraction data revealed that the polymer is crystalline. The unsaturation sites of the polymer chain could be exploited for crosslinking reactions. The swelling behavior of the crosslinked polymer was studied as well as the thermal and electrical properties. The overall thermal stability of the crosslinked polymer was found to be higher than that of the uncrosslinked polymer.

Study on models of double bond saturation during the synthesis of unsaturated polyesters

AbstractThe addition of hydroxyl groups on double bonds during the synthesis of unsaturated polyesters is studied with the help of model molecules. These are diesters of unsaturated diacids (maleic and fumaric acids) or monoesters of unsaturated monoacids (crotonic, cinnamic and p‐cyanocinnamic acids) with 1,2‐propanediol. The addition reaction take place to appreciable extents only with bis(hydroxypropyl) maleate and fumarate. The reaction is catalyzed by strong acids such as p‐toluenesulfonic acid; it is reversible and favoured by high temperatures. A mechanism is discussed.

Melting and crystallization behaviour of random copolymers from adipic acid, trans‐3‐hexenedioic acid and 1,16‐hexadecanediol

AbstractCopolyesters derived from adipic acid, trans‐3‐hexenedioic acid and 1,16‐hexadecanediol were prepared and investigated by means of X‐ray diffraction and DSC techniques. From the X‐ray results an isomorphous replacement of the saturated and unsaturated diacid units has been suggested. The equilibrium melting temperature T and the heat of fusion ΔHf were slightly dependent on the copolyester composition. The crystallization process was analyzed by means of Hoffman's kinetic crystallization theory for a lamellar type crystal growth. The values of the free energy of formation of a nucleus of critical dimensions ϕ* and the free energy of folding σe were found to decrease regularly with increasing amount of double bonds, varying from 110 to 83 kJ/mol for Δϕ* and from 171 to 127 erg/cm2 for σe. This effect has been interpreted on the basis of an increase of chain flexibility owing to the presence of the trans double bonds.

Bislactonization of unsaturated diacids using lead tetraacetate

The reaction of lead tetraacetate with unsaturated carboxylic acids (or salts) to from bislactones (γ or δ) can be controlled to produce efficiently cis addition of two carboxylic oxygens to the double bond, in consonance with an initial plumbolactonization step followed by S N2 displacement of lead.

Unstaurated polyester imides

AbstractImide‐containing polyesters have been prepared by melt polycondensation of propylene glycol with saturated and/or unsaturated diacids and imide diacids. These imide diacids have been synthesized from trimellitic anhydride and aliphatic ω‐amino acids, and differ from each other in the number of CH2groups.When mixtures of styrene and the unsaturated polyester imides are activated by peroxidic type initiators, crosslinked products are obtained, the properties of which can be related to the proportion of imide rings and the length of the aliphatic chain in its chemical structure.

X‐ray diffraction analysis of synthetic unsaturated diacid diglycerides

SummaryChemical and physical data are reported for the three diacid 1,3‐diglycerides obtainable from stearic, oleic, and elaidic acids. Two of these are new, namely 1‐stearyl‐3‐elaidin and 1‐oleyl‐3‐elaidin.X‐ray data have revealed one form for 1‐oleyl‐3‐elaidin and two forms for the other two diglycerides, with considerable individuality in the diffraction patterns of the compounds.