Related Diacid Research Articles

Structural and synthetic studies on maleic anhydride and related diacid natural products

A concise approach has been developed for the total syntheses of tricladic acids A, B and C previously isolated from Tricladium castaneicola confirming the structures of these fungal natural products. The required (E)-1,3-diene scaffolds were generated with complete stereocontrol via coupling of the appropriate nitronate with an unsaturated bromo-diester which was prepared in 2 steps from citraconic anhydride. The reported structures of the anhydride waquafranone B and the parent diacid were synthesised leading to revision of the originally proposed structure of the natural product and, in accord with Sutherland, confirming that cyclic anhydrides with exo-dienes are unstable. Biomimetic dimerisations of the proposed monomers of the nonadride scytalidin were investigated.

Novel and Convenient Synthesis of 2,7-Dialkyl-1,8-dihydro-as-indacenes­

A novel and convenient synthetic route towards dialkyl as-indacenes was achieved by alkylation of malonic esters with o-xylylene dibromide, to give the corresponding tetraester, and related diacid. The alkyl groups on the central benzene ring induce intramolecular, regiospecific cycloeliminations leading selectively to the diketones, the precursors of the corresponding 1,8-dihydro-as-indacenes. The structure of the 2,7-dimethyl-1,8-dihydro-as-indacene was determined by X-ray diffraction. The compound 2,7-diethyl-1,8-dihydro-as-indacene was characterized by means of 1H NMR, 13C NMR, FT-IR, UV/Vis measurements, electrochemistry, and elemental analysis. On the other hand, quantum chemical computations based on DFT methods were carried out to get insight into the molecular and electronic structures of the studied ligands. TDDFT approach was employed to calculate the vertical excitations and characterize the nature the UV/Vis absorption bands present in the experiments showing a very good agreement between experimental and calculated values. Finally, the reactivity of the compounds was assessed using the chemical potential (μ), chemical hardness (η), and electrophilicity (ω). Also, the electron-donating (ω–), electron-accepting (ω+), and the net electrophilicity powers (ω±) indexes were studied.

Soluble and thermally stable polyamides bearing 1,1′-thiobis(2-naphthoxy) groups

A new-type of sulfide containing diacid (1,1′-thiobis(2-naphthoxy acetic acid)) was synthesized from 2-naphthol in three steps. Reaction of 2-naphthol with sulfur dichloride afforded 1,1′-thiobis(2-naphthol) ( TBN). 1,1′-Thiobis(2-naphthoxy acetic ester) ( TBNAE) was successfully synthesized by refluxing the TBN with methylcholoroacetate in the presence of potassium carbonate. The related diacid was synthesized by basic solution reduction of TBNAE. The obtained diacid was fully characterized and used to prepare novel thermally stable poly(sulfide ether amide)s via polyphosphorylation reaction with different aromatic diamines. The properties of these new polyamides were investigated and compared with similar polyamides. These polyamides showed inherent viscosities in the range of 0.39–0.87 dL g −1 in N, N-dimethylacetamide (DMAc) at 30 °C and at a concentration of 0.5 g dL −1. All the polyamides were readily soluble in a variety of polar solvents such as DMAc and tetrahydrofuran (THF). These polyamides showed glass transition temperature ( T g) between 241–268 °C. Thermogravimetric analysis measurement revealed the decomposition temperature at 10% weight loss ( T 10) ranging from 441– 479 °C in argon atmosphere.

New poly(ester amide ether amide)s from a novel flexible diamine and different diacid chlorides using TMSCl for in situ silylation

A novel flexible diamine with built-in ester, amide and ether groups named terephthalic acid bis(4-{2-[2-(2-amino ethoxy)ethoxy]ethyl carbamoyl}phenyl) ester (TABE), was synthesized via two steps. Nucleophilic reaction of 4-hydroxybenzoic acid with terephthaloyl chloride in the presence of NaOH yielded terephthaloyl bis (4-oxybenzoic) acid (TOBA). The diamine (TABE) was prepared via two direct and indirect methods. In the indirect method TOBA was converted to related diacid chloride and reacted with 1,8-diamino-3,6-dioxaoctane (DADO). Direct method was achieved through the reaction of TOBA with DADO via Yamazaki method. TOBA and TABE were fully characterized and TABE was used to prepare new poly(ester amide ether amide)s through polycondensation with different diacid chlorides in the presence of trimethylchlorosilane (TMSCl). The polymers were characterized using conventional methods and their physical properties including inherent viscosity, thermal behavior, thermal stability, crystallinity, and solubility were studied. The polymers showed good thermal stability and improved solubility.

Synthesis, Characterization and Properties of Novel Poly(Ester‐Amide‐Urethane)s

AbstractA diacid (TOBA) containing an ester group was synthesized by reaction of terephthaloyl chloride with 4‐hydroxybenzoic acid. Reaction of the obtained diacid with thionyl chloride resulted in preparation of the related diacid chloride (TOBC). Nucleophilic substitution reaction of 4‐aminophenol and also 5‐amino‐l‐naphthol with the prepared diacid chloride afforded two aromatic diols containing ester and amide groups, respectively. Aromatic and semi‐aromatic poly(ester‐amide‐urethane)s were prepared via addition polymerization of different diisocyanates with novel diols. The prepared polyurethanes showed improved thermal stability.

Modification of cyanate ester resin by soluble polyarylates

AbstractSoluble polyarylates were prepared from the reaction of 2,2‐bis(4‐hydroxyphenyl)propane (bisphenol‐A) and aromatic acid dichlorides (phthaloyl chloride and related diacid dichlorides), and used to improve the brittleness of a cyanate ester resin. The polyarylates include poly[2,2‐di(4‐phenylene)propane phthalate] (PPA), poly[2,2‐di(4‐phenylene)propane phthalate‐co‐2,2‐di(4‐phenylene)propane isophthalate] (IPPA) and poly[2,2‐di(4‐phenylene)propane phthalate‐co‐2,2‐di(4‐phenylene)propane terephthalate] (TPPA). Furthermore, a commercial polyarylate, U‐polymer, was also used as a modifier. The morphologies of the modified resins depended on the polyarylate structure and concentration. The most effective modification of the cyanate ester resin could be attained because of the co‐continuous phase structure of the modified resin: 25 wt% inclusion of IPPA (50 mol% isophthalate units, weight average molecular weight (Mw) 38 500 g mol−1) led to a 130% increase in the fracture toughness (KIC) for the modified resin, with retention of its flexural properties and glass transition temperature, as compared with the values for the unmodified resin. Water absorptivity of the IPPA‐modified resin was smaller than that of the unmodified resin. Copyright © 2003 Society of Chemical Industry

Manganese(II) complexes of 3,6,9-trioxaundecanedioic acid (3,6,9-tddaH 2): X-ray crystal structures of [Mn(3,6,9-tdda) (H 2O) 2]·2H 2O and {[Mn(3,6,9-tdda)(phen) 2·3H 2O]·EtOH} n

3,6,9-trioxaundecanedioic acid (3,6,9-tddaH 2) reacts with Mn(CH 3CO 2) 2·4H 2O in ethanol to give [Mn(3,6,9-tdda)]·H 2O ( 1). Recrystallization of 1 from methanol gives crystals of [Mn(3,6,9-tdda) (H 2O) 2]·2H 2O ( 2). Complex 1 reacts with an ethanolic solution of 1,10-phenanthroline (phen) to give {[Mn(3,6,9-tdda)(phen) 2]·3H 2O·EtOH} n ( 3). All of the complexes are extremely water soluble. Complexes 2 and 3 were structurally characterised. The manganese(II) ion in 2 is seven coordinate, with an approximately pentagonal bipyramidal O 7 coordination sphere. The axial donors are water molecules and the pentagonal plane is occupied by the diacid, acting as a pentadentate ligand through the three ethereal oxygens and one oxygen atom from each of the carboxylate functions. In complex 3 the manganese(II) ion is six-coordinate, being bound to two bidentate phenanthroline ligands and to the carboxylate oxygen atoms from two symmetry related diacids which are coordinated in a cis fashion. The structure consists of polymeric chains, with diacid ligands bridging the manganese ions. There is π-π stacking of pairs of phenanthroline ligands on adjacent chains, running along both the z and y directions.

Synthesis and structure-activity studies on acidic amino acids and related diacids as NMDA receptor ligands.

The 3-isoxazolol amino acids (S)-2-amino-3-(3-hydroxy-5-methyl-4- isoxazolyl)propionic acid [(S)-AMPA, 2] and (R,S)-2-amino-2-(3-hydroxy-5-methyl-4-isoxazolyl)acetic acid (AMAA, 5a) (Figure 1) are potent and specific agonists at the AMPA and N-methyl-D-aspartic acid (NMDA) subtypes, respectively, of (S)-glutamic acid (1) receptors. A number of amino acids and diacids structurally related to AMAA were synthesized and tested electrophysiologically and in receptor-binding assays. The hydroxymethyl analogue 7c of AMAA was an NMDA agonist approximately equipotent with AMAA in the [3H]CPP-binding assay (IC50 = 7 +/- 3 microM) and electropharmacologically in the rat cortical wedge model (EC50 = 8 +/- 2 microM). In contrast to this, the tertbutyl analogue 7a of AMAA turned out to be an antagonist at NMDA and AMPA receptors. The conformational characteristics of AMAA and 7a, c were studied by molecular mechanics calculations. Compound 7a possesses extra steric bulk and shows significant restriction of conformational flexibility compared to AMAA and 7c, which may be determining factors for the observed differences in biological activity. Although the nitrogen atom of quinolinic acid (6) has very weak basic character, 6 is a, perhaps subtype-selective, NMDA receptor agonist and a potent neurotoxic agent. These aspects prompted us to synthesize and test the diacids 8a, b, in which the amino group of AMAA has been replaced by a methylthio and methoxy group, respectively. Neither compound showed significant affinity for nor depolarizing effects at NMDA receptors. The hydroxymethyl AMPA analogue 3c showed no interaction with NMDA receptors and only weak AMPA agonist effects.

Tetraphenylporphyrins monosubstituted with glycerol diester units. Synthesis and characterization

A novel 1-monoglyceryl ether of 5-(4-hydroxyphenyl)-10,15,20-tritolylporphyrin and related diacid esters with very high solubility in hydrophobic solvents were synthesized.

Thermogravimetric analysis of polyesters derived from terephthalic, tetrachloroterephthalic and related diacids with bisphenol A

The thermogravimetric behaviour of polyesters derived from terephthalic, tetrachloroterephthalic and related diacids, with -CH 2- and -OCH 2- as spacer groups with bisphenol A as diphenol, was studied by dynamic thermogravimetry. Polyesters derived from a diacid with an entirely aromatic structure degrade at higher temperatures than those derived from aliphatic diacids owing to the flexibility of the polymeric chain. Polyesters derived from tetrachloroterephthalic acid showed a higher thermal stability than that derived from terephthalic acid, but for the aliphatic polyesters, the chlorinated form showed a lower stability than those without chlorine atoms, probably because the influence of the aliphatic character is greater. The kinetics parameters of the thermal decomposition were determined by the Arrhenius relationship; in the range considered, all the studied polyesters degrade in a single stage, but probably via complex reactions.

Polymerization by phase transfer catalysis. 14. Polyesters from terephthalic acid and related diacids with bisphenol A

AbstractPolyesters were synthesized from the following acid dichlorides: terephthaloyl (I), p‐phenylenediacetyl (II), and p‐phenylenedi(oxyacetyl) (III) and bisphenol A as diphenol under phase transfer conditions. Quaternary ammonium and phosphonium salts were used as phase transfer catalysts in a 1,1,2,2‐tetrachloroethane/NaOH system. Polyesters were characterized by IR and 1H NMR spectroscopy, and elemental analysis. The influence of the catalysts and the reaction time were evaluated by the yields and ηinh values. The influence of the nature of the acid dichloride was higher than that of the catalysts due principally to the aliphatic character of the acid dichlorides II and III.

Polymerization by phase transfer catalysis. 15. Polyesters from tetrachloroterephthalic acid and related diacids with bisphenol A

AbstractChlorinated polyesters were synthesized from the following acid di‐chlorides: 2,3,5,6‐tetrachloro‐1,4‐terephthaloyl (I), 2,3,5,6‐tetrachloro‐1,4‐phenylenediacetyl (II), and 2,3,5,6‐tetrachloro‐1,4‐phenylenedi(oxyacetyl) (III), and bisphenol A, under phase transfer conditions, using several ammonium and phosphonium salts as catalysts and a biphasic CH2Cl2/NaOH system. The influence of the nature of the catalysts and the reaction times were evaluated by the yields and ηinh of the polyesters. The reactivity of the monomers was I<II<III, due to the smaller influence of the tetrachlorinated ring when there is a spacer group between the aromatic ring and the acid chloride group.

Thermogravimetric analysis of poly(ether-ester)s derived from bisacid A-2 and related diacids and diphenols

The thermogravimetric behaviour of nine poly(ether-ester)s derived from three acid dichlorides and three diphenols was studied by dynamic thermogravimetry. The thermal decomposition temperatures (TDT), the temperature at which the poly(ether-ester)s lost 10% of their weight, were also determined; they are within 30°C of each other. The kinetics parameters of the thermal decomposition were also determined. The poly(ether-ester)s in which the structures of the acid dichloride and the diphenol were the same, showed a 0 kinetic order, but when those structures were different the kinetic order was 0.5, which means that the degradation is a complex process.

Polymerization by phase transfer catalysis. 12. Poly(ether‐ester)s from (2,2‐bis(1,4‐phenyleneoxy)‐propylidene)‐diacetic acid and related diacids with diphenols

AbstractPoly(ether‐ester)s from (2,2‐bis(1,4‐phenyleneoxy)‐propylidene)‐diacetic acid and related diacids with diphenols were synthesized using several ammonium and phosphonium salts as phase transfer catalysts. The best results were obtained with benzyltriethylammonium chloride, which is a hydrophilie catalyst that not promotes hydrolysis of the polymeric chains. Other onium salts also were effective as phase transfer catalysts. Polymers were characterized by IR and 1H‐NMR spectroscopy and elemental analysis. Molecular weights were estimated by inherent viscosity measurements.