A method for the determination of chain microstructure of hydrolyzed poly(acrylonitrile) (PAN) and of copolymers of acrylonitrile with acrylamide by means of 13C NMR spectroscopy is described. Besides the overall composition of poly(acrylonitrile-co-acrylamide), this method permits the population of all acrylamide-centered compositional triads to be determined; it is then possible to follow the values of the rate constants of nitrile group hydrolysis in dependence on its neighbours. Under certain circumstances the knowledge of the mentioned triads permits also the copolymerization parameters for copolymerization of acrylonitrile with acrylamide to be determined. It was confirmed that acid-catalyzed hydrolysis of PAN in concentrated nitric acid yields acrylonitrile-acrylamide block copolymers.

Analysis of 13C NMR spectra of methylethers of the type CH3OCH2R, with R = CH3 (I), CH2CH3 (II), CH(CH3)2 (III) and C(CH3)3 (IV) has shown that the trans form strongly predominates on the OCH, bond, the gauche forms appearing only in those cases where close contact between methyl groups can be avoided. Analysis of both 1H and 13C NMR spectra indicates that all staggered forms are populated on the CH2R bond. In vibrational spectra, the strong Raman bands near 800 cm−1 were found to be very sensitive to conformational structure. For I, III and IV, the bands of various conformers in this range are separated, permitting ΔH to be determined.

A study is presented of 1H and 13C CIDNP effects in the reactions of Na and Li salts of ketyls and dianions derived from benzophenone and fluorenone with acetic anhydride in tetrahydrofuran and dimethoxyethane. CIDNP effects were observed for products obtained by mixing of reactants both at high and at low field. Interpretation of the CIDNP effects (mixing at high field) indicates that in reactions of ketyls with acetic anhydride the primary step is O-acylation followed by spin-selective electron transfer between ketyl and O-acylated ketyl. At higher dilution or in the presence of strongly coordinating agents, heterolytic deprotonation of acetic anhydride by ketyl is also observed. CIDNP effects depend on the presence of ketyl which affects the relaxation of sterically accessible nuclei and also suppresses the intensity of ketone signals by rapid electron transfer. In reactions of dianions, electron transfer between dianion and acetic anhydride partly takes place, and the ketyl formed in this way reacts with a further molecule of acetic anhydride.

By analysis of infrared, Raman and 13C NMR spectra of 2,2-dimethyl-1-methoxypropane and of the methyl ester of 3-methoxy-2,2-dimethylpropanoic acid, the formation of conformers generated by rotation about the CH2-OCH3 and C-CH2 bonds was studied. It was found that in both molecules, only the form with trans orientation of the C-CH2-O-CH3 bonds is present. The conformational structure of the major form of the methyl ester of 3-methoxy-2,2-dimethylpropanoic acid was proposed.

AbstractThe mechanism of acid curing of epoxy resins catalyzed with tertiary amines was investigated by using model systems composed of phenylglycidyl ether and benzoic acid or acetic acid anhydrides in the presence of benzyldimethylamine. The reaction was studied by NMR spectrometry, liquid chromatography, and ozone absorption. The main findings are that (1) the tert‐amine is bound chemically and irreversibly during the reaction under the formation of a quaternary ammonium salt magnified image and (2) 1‐phenyloxypropanediol‐2,3‐dibenzoate or diacetate is the main reaction product. The suggested reaction mechanism involves initiation in which the tertiary amine reacts with the epoxy group, giving rise to a zwitterion that contains a quaternary nitrogen atom and an alkoxide anion; the latter immediately reacts with the anhydride and quaternary salt is formed. In a later stage the carboxy anion of the quaternary salt reacts first with the epoxy group, then with the anhydride. By this reaction diester is formed and the carboxy anion is regenerated.

Infra-red and Raman spectra of unoriented samples of poly(ethylene terephthalate) in the crystalline and amorphous states and in solution were measured. The dissolved polymer was also studied by n.m.r. spectra. Digital separation of the vibrational spectra of amorphous and crystalline components made possible the detection of some new bands, the interpretation of which is presented. By comparison with the vibrational spectra of model compounds combined with analysis of n.m.r. spectra, the conformational forms present in the amorphous and liquid states of poly(ethylene terephthalate) were characterized and their populations were determined. Bands in vibrational spectra which are characteristic of various conformational forms were defined.

Infrared and Raman spectra of ethyl benzoate and diethyl terephthalate were measured in their crystalline forms, in the glassy state and in the melt. With liquid samples, the NMR coupling constants 3JCH of the group -CO.O.CH2- were also measured. By analysis of these measurements it was found that in the liquid state of ethyl benzoate the following conformers are present: forms with a fully planar structure; forms with the methyl group twisted out of the aromatic and ester group plane by rotation about the O-C2H5 bond; and forms with non-planar mutual orientation of the ester group and the aromatic ring, formed by rotation about the Car-CO or CO-O bonds. The first two forms are also present in the crystalline modifications of ethyl benzoate. Diethyl terephthalate in the liquid state is present in forms analogous to those of ethyl benzoate; in addition, it contains isomers differing by the mutual orientation of the two ester groups on the aromatic ring.

Complex formation between N-methylated lactams (L) with 11- and 13-membered rings which in the liquid state assume both the cis and the trans structures of the amide bond, and TiCl4, (M) in 1,1,2,2-tetrachloroethane and CDCl3 solutions has been studied by analysis of 1H and 13C-NMR and Raman spectra. The composition and structure of the complexes as well as the effect of TiCl4, on the cis—trans isomerization equilibrium have been determined. As for the lower cis lactams, it was found that at molar ratios [L]:[M] > 2, the lactams with the 11- and 13-membered rings form complexes of composition ML2. The free energies of activation for the exchange processes in these systems were estimated from the temperature dependence of 1H-NMR spectra and it was found that the barrier to rotation about the amide bond is increased by complex formation.

By analysis of 1H- and 13C-NMR spectra it has been found that in 1,1,2,2-tetrachloroethane-d2 and CDCl3 solutions, the lactams (L) 1-methyl-1-azacycloheptca-2-one and 1-methyl-1-azacyclonona-2-one form with TiCl4 (M) at mole ratios [L]: [M] > 2 two types of complexes of composition ML2, which differ in the geometrical arrangement of the ligands. The thermodynamic parameters of the exchange of lactams between the two complexes and the uncomplexed state were determined from the temperature dependence of 1H-NMR line shapes and found to be independent of the lactam ring size.

It was found that three crystalline forms of ethylene glycol dibenzoate can be prepared. Infrared and Raman spectra of these three forms, as well as of the glassy and liquid states, were measured. From 3JHH coupling constants obtained by analysis of the 13C satellite band of the -CH2- group in 1H NMR spectra, and from the 3JCH coupling constants of the -CO.O.CH2- fragment obtained by analysis of the carbonyl band in 13C NMR spectra it was found that in the liquid state the -CH2-CH2- group exists predominantly in the gauche conformational structure, and the bonds C-O-C-C assume predominantly a trans orientation. The results of the analysis of NMR and vibrational spectra were used for the structural interpretation of conformationally sensitive bands in vibrational spectra of ethylene glycol dibenzoate.

From 1H-NMR spectra of 1-methyl-azacyclo-undeca-2-one and 1-methyl-azacyclo-trideca-2-one, the bands corresponding to the cis and trans forms have been assigned and analyzed; based on this analysis, conformational structures about the C-C bond next to nitrogen are proposed. By analysis of the relative areas and shapes of the N-methyl bands measured for the two lactams in 1,1,2,2-tetrachloroethane-d2, over a broad temperature range, the equilibrium and thermodynamic parameters characterizing the cis—trans isomerism of the amide bond in these lactams have been determined. Peaks corresponding to the cis and trans forms in the 13C-NMR spectra of these lactams have also been assigned.

From analysis of 1H and 13C NMR and Raman spectroscopic data, in CDCl3 and 1,1,2,2-tetrachloroethane-d2 solution, the lactam 2-methyl-2-azabicyclo-[2,2,2]-octa-3-one (L) was found to form complexes with TiCl4 (M) of overall composition M2L, ML and ML2. Two forms of the ML2 complex were observed by NMR. In all these complexes, Ti coordinates to the carbonyl oxygen, and the metal—carbonyl bond is of the same type. The complexes ML and ML2 contain hexacoordinated Ti; in M2L the coordination number is probably five. The dynamics of exchange of the lactam between the ML2 complexes and the uncomplexed form have been characterized and structures are proposed for the four complexes.

4-Amino-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMP-NH2) is a spin label suitable for the investigation of polymer systems. The analysis of EPR spectra of spin-labeled samples intended for the determination of the type and correlation time of spin-label rotational reorientation in the system under study requires the knowledge of the proton splitting constants, the hyperfine interactions tensor AN, and the g tensor of this nitroxide. The splitting constants were determined by the NMR method from differences in the shifts of protons in the spectra of nitroxide and of its diagmagnetic analog, 4-amino-2,2,6,6-tetramethylpiperidine. By analyzing the rigid-limit EPR spectrum of 4-acetamino-perdeutero-2,2,6,6-tetramethylpiperidine-N-oxyl recorded in CD30D, we determined the tensors AN and g in this solvent.

The structures of the stable conformers of N-methyjpropionamide and N-methyliso-butyroamide in CCl4, solution were determined by a combination of IR spectroscopy and NMR spectroscopy with lanthanide shift reagents. N-methyl-propionamide was found to exist in the form of two rotational isomers, 1 and 2, with the ethyl group twisted out of the plane of the amide bond by the angles Ψ = 140 and 20°, respectively. For these two conformers, the enthalpy difference is ΔH = 2.13 ± 0.08 kcal mole−1 and the entropy difference ΔS = 7.81 ± 0.55 cal mole−1 grad−1. N-methylisobutyroamide exists in a single form, with the two C-methyl group positions very close to those found in the two isomers of N-methylpropionamide.

Chemischer InformationsdienstVolume 7, Issue 19 Article ChemInform Abstract: STUDIES IN THE PYRIDINE SERIES. L. ELECTROLYTIC REDUCTION OF QUATERNARY SALTS S OF SOME ALCOHOLS OF THE PYRIDINE SERIES, OF CORRESPONDING ALKYLPYRIDINES AND ALKENYLPYRIDINES M. FERLES, M. FERLESSearch for more papers by this authorO. KOCIAN, O. KOCIANSearch for more papers by this authorM. LEBL, M. LEBLSearch for more papers by this authorJ. LOEVY, J. LOEVYSearch for more papers by this authorS. RADL, S. RADLSearch for more papers by this authorA. SILHANKOVA, A. SILHANKOVASearch for more papers by this authorP. STERN, P. STERNSearch for more papers by this author M. FERLES, M. FERLESSearch for more papers by this authorO. KOCIAN, O. KOCIANSearch for more papers by this authorM. LEBL, M. LEBLSearch for more papers by this authorJ. LOEVY, J. LOEVYSearch for more papers by this authorS. RADL, S. RADLSearch for more papers by this authorA. SILHANKOVA, A. SILHANKOVASearch for more papers by this authorP. STERN, P. STERNSearch for more papers by this author First published: May 11, 1976 https://doi.org/10.1002/chin.197619105Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume7, Issue19May 11, 1976 RelatedInformation

Die elektrolytische Reduktion der Alkohole (Ia) und (IIa) führt zu den Isopropylchinolinen (Ib) bzw. (IIb) und im Falle (IIa) zusätzlich zu dem Tetrahydrochinolin (IIIa).

AbstractDie elektrolytische Reduktion der Alkohole (Ia) und (IIa) führt zu den Isopropylchinolinen (Ib) bzw. (IIb) und im Falle (IIa) zusätzlich zu dem Tetrahydrochinolin (IIIa).