Synthesis of polyesters as binders for deinkable inks. I. Structural analysis of the polyesterification between o-phthalic anhydride and neopentyl glycol in bulk at 200°C by high resolution 13C nuclear magnetic resonance (13C-NMR)

Analysis of the polyesterification in bulk without any external catalyst at 200°C of o-phthalic anhydride with neopentyl glycol (2,2-dimethyl-1,3-propanediol) with a mole ratio ([(SINGLE BOND) COOH]/[ (SINGLE BOND) OH]) = 0.7 has been carried out by high resolution ¹³C nuclear magnetic resonance (¹³C-NMR). Polyesters can be analyzed by ¹³C-NMR spectra because of the fact that both o-phthalic acid (o-phthalic anhydride) and neopentyl glycol carbons are sensitive to sequence effects. Spin-lattice relaxation times T₁, of quaternary, tertiary and secondary carbons in different structures are in the 0.1–6.5 s range depending on the neighboring residue effects in the polymer chain. © 1996 John Wiley & Sons, Inc.     

Study of the synthesis of poly(isobutylene-b-amide-11) by polycondensation of α,ω-dianhydride oligoisobutylene with α,ω-diamino oligoamide-11. I. Study of amine–anhydride and amide–anhydride reactions on low molecular weight models and on oligomers and polymers

The side reactions connected with the polycondensation of α,ω-diamino oligoamides and α,ω-dianhydride oligoisobutylenes are studied on low and high molecular weight models. Models for amine and anhydride end groups are dodecylamine and (2-dodecene-1-yl) succinic anhydride, respectively; their reaction is studied in the bulk (170°C) and in solution (142, 152, and 162°C); the products are analyzed by ¹H-, ¹³C-, and ¹H-¹³C-NMR and GPC. Some of these products and the junctions between the blocks are prepared independently. Models of amide groups in the chain are N-dodecyldodecanamide and N-dodecyloctadecanamide; their reaction with anhydride model results in cleavages with formation of imide groups. The results obtained from low molecular weight models are confirmed by studies on oligomers. They show unambiguous by that crosslinking which accompanies the block polycondensation originates from the reaction of amino-end groups with the intermediary acid groups resulting from the amine-anhydride reaction.     

Radical cyclocopolymerization of divinyl ether and maleic anhydride. A 13C-NMR study of the polymer structure

The structure of the 1:2 copolymer of divinyl ether and maleic anhydride was investigated by ¹³C-NMR spectroscopy. The polymer contains the bicyclic unit composed of one molecule of each monomer and the maleic anhydride unit. The carbon chemical shift for these units was calculated on the basis of the chemical shift of many model compounds. The major peaks of the cyclopolymer prepared in chloroform were consistent with the presence of the symmetrical bicyclic unit with cis junction and the trans monocyclic anhydride unit. The carbonyl carbon spectrum for the copolymer obtained in a mixed solvent of acetone and CS₂ suggested the predominant formation of the unsymmetrical bicyclic unit. The polymerization process was discussed on the basis of these results.     

Grafting of maleic anhydride to n-eicosane

Maleic anhydride was grafted to the linear hydrocarbon, n-eicosane, at 165°C in the presence of the free radical initiator, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne. The anhydride has a low solubility in eicosane and a multiple addition procedure was adopted. Grafted product which separated from the reaction mixture was fractionated and analyzed. The fractions contained on average 2–5.5 anhydride units/eicosane residue. ¹H- and ¹³C-NMR studies show that the grafts consist of single succinic anhydride rings. At the concentrations of maleic anhydride chosen for homogeneous reaction ( < 0.02 M) and at 165°C, poly(maleic anhydride) is above its ceiling temperature, so that succinic anhydride radicals cannot add maleic anhydride to form polymer side chains. Instead, these radicals abstract hydrogen atoms to yield grafts consisting of single anhydride units.     

13C?C13 coupling constants in dimethyl phthalate and phthalic anhydride. Determination of signs—III

Relative signs of ¹³C? ¹³C coupling constants between ring carbons and carbonyl carbons in dimethyl phthalate and phthalic anhydride, ¹³C-labelled in both carbonyl groups, have been determined. The two-and three-bond coupling constants are shown to be positive, whereas four-bond coupling constants are negative. Substituent effects on carbon-carbon couplings due to a carboxyl group have been determined and effects of 5-membered ring formation in phthalic anhydride have been observed.     

Synthesis and Structure of Tetrahydro-4,7-ethanoisobenzofuran-1,3-dione Derivative

(1R,2R,3S,4R,7R)‐7‐Isopropyl‐6‐methylbicyclo[2.2.2]oct‐5‐ene‐2,3‐dicarboxylic acid anhydride (tetrahydro‐4,7‐ethanoisobenzofuran‐1,3‐dione derivative) adduct 2 was prepared via the isomerization of α‐pinene and β‐pinene in turpentine followed by the Diels‐Alder cycloaddition with maleic anhydride in the presence of phosphoric acid/iodine catalysis. The molecular structure of adduct 2 was characterized by IR, ¹H NMR, ¹³C NMR, ¹H‐¹H COSY, DEPT, HSQC, HMBC, 2D NOESY and MS spectra. The single crystal X‐ray crystallographic analysis of adduct 2 was performed, and the X‐ray powder diffractive spectrum of the sample adduct 2 is consistent with the diffractive spectrum calculated from the single crystal data. Therefore the structure and stereochemistry of adduct 2 was established based on extensive spectral data and single crystal X‐ray analysis.     

Chemistry of the phenoxathiins and isosterically related heterocycles. XI . The synthesis and 13C-NMR spectroscopy of 2-azaphenoxathiin

The synthesis of the 2-azaphenoxathiin ring system via the intermediary 2-azaphenoxathiin 2-oxide is described. Complete assignment of the ¹³C-nmr spectrum is reported, based on the observed heteronuclear ¹H-¹³C spin-couplings of the system and calculated chemical shifts as assignment criteria. The possible relation of the chemical shift of Cα to the dehidral angle of the system is also discussed.     

Bioengineering functional copolymers. III. Synthesis of biocompatible poly[(N‐isopropylacrylamide‐co‐maleic anhydride)‐g‐poly(ethylene oxide)]/poly(ethylene imine) macrocomplexes and their thermostabilization effect on the activity of the enzyme penicillin G acylase

Stimuli‐responsive poly[(N‐isopropylacrylamide‐co‐maleic anhydride)‐g‐poly(ethylene oxide)]/poly(ethylene imine) macrobranched macrocomplexes were synthesized by (1) the radical copolymerization of N‐isopropylacrylamide and maleic anhydride with α,α′‐azobisisobutyronitrile as an initiator in 1,4‐dioxane at 65 °C under a nitrogen atmosphere, (2) the polyesterification (grafting) of prepared poly(N‐isopropylacrylamide‐co‐maleic anhydride) containing less than 20 mol % anhydride units with α‐hydroxy‐ω‐methoxy‐poly(ethylene oxide)s having different number‐average molecular weights (M_n = 4000, 10,000, or 20,000), and (3) the incorporation of macrobranched copolymers with poly(ethylene imine) (M_n = 60,000). The composition and structure of the synthesized copolymer systems were determined by Fourier transform infrared, ¹H and ¹³C NMR spectroscopy, and chemical and elemental analyses. The important properties of the copolymer systems (e.g., the viscosity, thermal and pH sensitivities, and lower critical solution temperature behavior) changed with increases in the molecular weight, composition, and length of the macrobranched hydrophobic domains. These copolymers with reactive anhydride and carboxylic groups were used for the stabilization of penicillin G acylase (PGA). The conjugation of the enzyme with the copolymers significantly increased the thermal stability of PGA (three times at 45 °C and two times at 65 °C). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1580–1593, 2003     

A Novel and Efficient Synthesis of Pyrido[1,2‐a]‐Fused 1,3‐Diazaheterocyclic Compounds via a One‐Pot Three‐Component Reaction

An efficient one‐pot synthesis of pyrido[1,2‐a]‐fused 1,3‐diazaheterocyclic compounds by three‐component reaction of diamine, nitroketene dithioacetal (=1,1‐bis(methylsulfanyl)‐2‐nitroethene), and electron‐poor itaconic anhydride (=2‐methylidenesuccinic anhydride=2‐methylidenebutanedioic anhydride) in aqueous EtOH is reported. This protocol has the advantages of easiness, higher yields, and shorter reaction times. The structures were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this type of cyclization is proposed (Scheme 2).     

Characterization of novel modified amorphous poly (ether sulphone)s

New high-temperature amorphous polymers with chlorine, amine, and maleimide chain-ends have been synthesized by nucleophilic polycondensation and fully characterized by ¹³C-NMR, ¹H-NMR, and potentiometric titration. From chain-end determination, number average molecular masses were calculated. It was confirmed that transetherification during the synthesis led to a randomized polymer of the monomer residues. For nominally amine-ended polymers obtained by addition of m-aminophenol at the end of the synthesis, a small amount of hydroxyl chain-ends was observed. This is ascribed also to transetherification. Complete reaction of the amine chain-ends with maleic anhydride was demonstrated. Reaction of hydroxyl chain-ends with acetic anhydride was also observed. The thermal stability of these different polymers was investigated; lower thermal stability was observed for amine and maleimide-ended polymers. By two different methods, a T_g around 270d°C was determined for these novel amorphous aromatic polymers. © 1994 John Wiley & Sons, Inc.     

Model studies on the kinetics and mechanism of polyarylate synthesis by acidolysis

Model reactions were carried out to simulate the acidolysis process for polyarylate synthesis by using p-tert-butylphenyl acetate (ptBuPhOAc) and benzoic acid in diphenyl ether. p-tert-Butylphenol was formed in the reaction mixture and its concentration stayed constant throughout the reaction. Acetic benzoic anhydride and benzoic anhydride were detected by NMR. Based on this experimental evidence, a mechanism for the acidolysis was proposed involving the mixed anhydride. The kinetics of the acidolysis reaction was studied for this model reaction. The overall reaction order is two and the reaction order with respect to each reactant is one. Second-order reaction rate constants were measured at different reaction conditions (200–250°C). The activation energy (E_a), activation enthalpy (ΔH^≠), and activation entropy (ΔS^≠) were calculated from these data. The thermodynamic parameters of the acidolysis reaction were also measured for the analogous reaction of p-tert-butylphenyl pivalate (ptBuPhOPiv) and benzoic acid. The kinetics of two other elementary reactions involved in the acidolysis reaction were also studied: p-tert-butylphenol with acetic anhydride or benzoic anhydride, and p-tert-butylphenyl pivalate with benzoic acid.     

2-Amino-4-aryl-1-arylideneaminoimidazoles and Acylation Products: A Multinuclear ( 1H, 13C, 15N) NMR Study

The structure of 2-amino-4-aryl-1-arylideneaminoimidazoles in DMSO-d₆ solution was investigated by means of NMR spectroscopic methods (¹H, ¹³C, ¹⁵N). From these data the (E)-configuration at the excocyclic C=N bond and a strong preference for the conformer with the imidazole H-5 and the N=CH proton being spatially close (s-trans regarding the N–N bond) can be concluded. Reaction of the title compounds with acetic anhydride leads to mono and diacylation at the 2-amino group, whereas treatment with pivalic anhydride exclusively affords the corresponding monoacyl product. The mono- and diacylation products exhibit similar configurational and conformational properties as the parent compounds.     

Characterization of chloroprene and maleic anhydride copolymer by 13C-NMR spectroscopy and pyrolysis GC/MS

The radical copolymerizations of chloroprene (CP) and maleic anhydride (MAH) were carried out with AIBN in 1,4-dioxane at 60°C. The monomer reactivity ratios were estimated as r₁ (CP) = 0.38 and r₂ (MAH) = 0.07. Microstructures in the copolymer of chloroprene (CP) and maleic anhydride (MAH) were investigated by 75.4 MHz ¹³C-and 300 MHz ¹H-NMR spectroscopies. Resonances were assigned to the monomer sequence dyads CC, CM, and MC (C = chloroprene, M = maleic anhydride). Well resolved fine structure in the ¹³C-NMR spectra showed that 1,2- and 3,4-structural chloroprene units were negligible in the copolymer. The pyrolysis characterization of the copolymer was also investigated by the pyrolysis gas chromatography mass spectrometry (GC/MS). The fragments of CP and MAH monomers and CP-MAH hybrid dimer, CO, and CO₂ were identified after pyrolysis of the copolymer. © 1994 John Wiley & Sons, Inc.     

Synthesis of bacillamide 3 and its analogue

The bacillamide 1 is a new algaecide from the marine bacterium Bacillus sp. SY-1. Its analogues bacillamide 3 and alkaloid 4 were firstly synthesized effectively from d-alanine. The key step was a coupling reaction via the mixed anhydride. All structures were confirmed by ¹H NMR and ¹³C NMR. The final compounds were confirmed by ¹H NMR, ¹³C NMR and HRMS and the results are consistent with the reported natural products.     

Substituent effects on one-bond 15N?13C couplings in N,N-dimethylanilines and nitrobenzenes. Effect of steric inhibition of conjugation

The ¹J(¹⁵N¹³C) values for a series of ring-substituted N,N-dimethylaniline-¹⁵N derivatives and a series of nitrobenzene-¹⁵N derivatives were measured from the ¹³C spectra. In the nitrobenzenes, small changes in ¹J(¹⁵N¹³C) are attributed to the inductive effect of the substituents, since steric inhibition of conjugation has little effect on the magnitude of the coupling. In contrast, steric inhibition of nitrogen lone-pair delocalization in N,N-dimethylaniline derivatives markedly reduces the value of ¹J(¹⁵N¹³C). Theoretical calculations of ¹J(¹⁵N¹³C) values for the two series of compounds were made using standard INDO parameters and a ‘sum-over-states’ perturbation approach. Fair agreement between the calculated and experimental values is found.     

Metal formyl complexes. The reaction of sodium pentacarbonylmanganate with acetic[13C]formic anhydride

The reaction of acetic [¹³C]formic anhydride with sodiumpentacarbonylmanganate proceeds rapidly at 0°C to give ¹³CO substituted pentacarbonylmanganese hydride as the predominant product. The results are consistent with the formation of a short-lived neutral formyl complex, (CO)₅Mn¹³CHO.     

2-Amino-4-aryl-1-arylideneaminoimidazoles and Acylation Products: A Multinuclear (<Superscript>1</Superscript>H, <Superscript>13</Superscript>C, <Superscript>15</Superscript>N) NMR Study

Summary. The structure of 2-amino-4-aryl-1-arylideneaminoimidazoles in DMSO-d₆ solution was investigated by means of NMR spectroscopic methods (¹H, ¹³C, ¹⁵N). From these data the (E)-configuration at the excocyclic C=N bond and a strong preference for the conformer with the imidazole H-5 and the N=CH proton being spatially close (s-trans regarding the N–N bond) can be concluded. Reaction of the title compounds with acetic anhydride leads to mono and diacylation at the 2-amino group, whereas treatment with pivalic anhydride exclusively affords the corresponding monoacyl product. The mono- and diacylation products exhibit similar configurational and conformational properties as the parent compounds.     

The structure of α-(1,2-dithiole-3-ylidene) ketones and α-(1,2-dithiole-3-ylidene) aldehydes studied by means of n.m.r. spectroscopy

1H and ¹³C n.m.r. studies of a series of twelve 1,2-dithiole-3-ylidene ketones and aldehydes have shown that the geometry of the carbon backbone is the same as found in 1,6,6aλ⁴-trithiapentalenes. No evidence has been found which favours a bicyclic structure for the system. A linear correlation of observed ¹³C chemical shifts with calculated charge densities is found to be valid. The observations are in agreement with a structure which is a hybrid between a true ketonic structure and a true mesoionic structure. By using the difference in the ¹³C chemical shifts of ortho and meta carbon atoms in substituent phenyl groups it is possible to qualify the degree of coplanarity of the phenyl groups with the backbone of the molecule.     

New polymer syntheses. CXI. Aliphatic polyesters by the ring‐opening polycondensation of glutaric anhydride with ethylene or trimethylene carbonate

Several polycondensations of ethylene carbonate with succinic anhydride or glutaric anhydride (GA) were conducted in bulk. Low molar mass polyesters were obtained with pyridine‐type catalysts and GA. Analogous polycondensations of trimethylene carbonate (TMC) and GA were successful when quinoline, 4‐(N,N‐dimethylamino)pyridine, or BF₃ · OEt₂ was used as a catalyst. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectra revealed the formation of cyclic oligoesters and polyesters by backbiting degradation. Monomer mixtures containing an excess of TMC yielded copoly(ester carbonate)s with number‐average molecular weights up to 16,000 Da. Analogous copoly(ester carbonate)s were obtained from TMC and 3,3′‐tetramethylene glutaric anhydride. Furthermore, combined polycondensation/ring‐opening polymerization reactions of TMC and GA with L ‐lactide or ?‐caprolactone were studied. All copolymers were characterized by viscosity measurements and by IR, ¹H, and ¹³C NMR spectroscopy. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4357–4367, 2002     

Temperature effects on 13C n.m.r. chemical shifts of normal alkanes and some line r and branched 1-alkenes

¹³C n.m.r. chemical shifts of a number of 1,1-disubstituted ethylenes are presented. Moreover, effects of changing temperatures on the ¹³C n.m.r. chemical shifts of some of these compounds as well as of three normal alkanes are given. These variations in chemical shifts are attributed to varying amounts of sterically induced shifts in the different conformational equilibria. In addition to the well-known 1,4 interaction between two alkyl groups shielding effects on the carbon atoms of the connecting bonds are also proposed. No definite explanation of this effect is presented at this time. It is further shown that no simple correlations exist between ¹³C n.m.r. chemical shifts and calculated total charge densities at this level. Instead, the experimental results in 1-alkenes are rationalized by assuming a linear dependence of the ¹³C n.m.r. chemical shifts of C-1 and C-2 via rehybridizations on changes in bond angles for small skeletal deformations caused by steric interactions. These changes in geometries, as well as conformational energies in three 1-alkenes, were calculated by means of VFF calculations. Finally. upfield shifts for both C-2 and C-4 are proposed for those conformations of 1-alkenes in which the C-3? C-4 group interacts with the p_z-orbital of C-2.