PMR Data Research Articles

Triorganoantimony(V) Complexes with Monobasic Bidentate Ligands

Abstract Triorganoantimony(V) compounds of the type R3SbBrL, where R is phenyl or methyl group and L is a bidentate anionic group of ethyl acetoacetate (eaa), salicyaldehyde (sal), o-hydroxyacetophenone (hap) and 2-hydroxy-1-napthaldehyd (hna) have been prepared. Molecular weight determinations in freezing benzene indicate that these molecules are monomeric in benzene solution. Elemental analyses, IR and PMR data suggest that L acts as a bidentate ligand furnishing an octahedral environment for the antimony atom.

Synthesis and study of tautomeric properties of 2-(5-R-2-furyl)thiazolin-4-ones

Compounds were synthesized by reaction of 5-R-2-cyanofurans with thioglycolic acid, which, according to IR, PMR, and mass spectrometric data, exist in the form of two tautomers, 4-hydroxythiazole and thiazolin-4-one.

Localization of the protons in x-ray crystallographic analysis using correlation equations for the H bond and PMR data

By analysis of the relationships governing hydrogen bond formation a method is proposed for the localization of the protons from the PMR data of polycrystalline samples in structures where the position of the heavy atoms, including the oxygen atoms, are known. The results are compared with the coordinates of the protons obtained for yttrium oxalate by neutron diffraction.

Synthesis and pharmacological activity of 5,6-and 4,5-ethylenedioxytryptamines

It should be noted that with the Japp--Klingemann reaction hydrazone II is obtained in the syn form, which was confirmed by PMR data in CDCI~ (chemical shift of 7 NH is 12.73 ppm). The syn form of hydrazone II is easily converted to the anti form by dissolving it in DMF, which was also confirmed by PMR spectral data (chemical shift of 7 NH is 9.52 ppm), The displacement of the 7 NH signal of the anti form of II to high field is explained by the rupture of the intramolecular hydrogen 5ond present in the syn form of the hydrazone.

Proton and deuteron magnetic resonance study of Sr(BrO3)2.H2O and Sr(BrO3)2.D2O

Proton and deuteron magnetic resonance experiments have been carried out on Sr(BrO3)2.H2O at RT. From PMR data the hydrogen positions have been calculated by means of a simple method which makes use of the crystal symmetry. The EFG parameters obtained from the DMR data indicate that the D2O molecules are executing rapid 180 degrees flips at RT giving rise to an averaged EFG tensor. From the results of a point charge calculation of the EFGs, the validity of hydrogen coordinates derived from PMR is confirmed. Again, making use of the symmetry considerations, component tensors are extracted from the room-temperature-averaged tensors. The hydrogen bonding in isostructural Ba(ClO3)2.H2O, Ba(BrO3)2.H2O and Sr(BrO3)2.H2O is discussed in relation to the presence of superfine interactions observed in EPR studies of gamma -irradiated Ba(ClO3)2.H2O and Ba(BrO3)2.H2O.

Proton and deuteron magnetic resonance study of Cd(BrO 3) 2 · 2H 2O and Cd(BrO 3) 2 · 2D 2O

Proton and deuteron magnetic resonance experiments have been carried out on Cd(BrO 3) 2 · 2H 2O and Cd(BrO 3) 2 · 2D 2O at room temperature. From the PMR data, proton—proton directions in the unit cell are derived and hydrogen coordinates are calculated using an empirical procedure. From the DMR data electric field gradient (EFG) parameters seen by the 2D are derived and from the characteristics of the EFG parameters it is concluded that the D 2O molecules are executing rapid 180° flips at 300 K. The hydrogen coordinates derived from PMR data are supported by means of a point charge calculation of the EFG parameters. The hydrogen bonding is discussed in relation to the presence of super hyperfine interactions observed in the EPR studies of γ-irradiated Cd(BrO 3) 2 · 2H 2O. Point charge calculations show that one of the characteristics of the averaged tensor based on the flipping model need not necessarily be valid.

The Synthesis of Indeno[l,2:4,5]pyrimido[l,2-a]benzimidazole-13-ones, Indeno[l,2-b]pyrazolo[4,3-e]pyridine-3,5-dione and Related Compounds*

2-A rylidene-l,3-indaniones (1a and 2b ) reacts with 2-aminobenzimidazole in absolute ethanol, to yield 12,12a-dihydro-12-aryl-13H̱-indeno[1̄,2̄̄̄:4,5]pyrim ido[1,2-a̱]benzimidazole-13-one (2a and 2b). Treatm ent of 2a with PPA gave 15aH̱ -dibenzo[2̄,3̄:4̄,5̄]pentaleno[1̄,6̄:4,5,6]pyrimido- [1,2-a̱]benzimidazole (5). While the condensation of 1c with 3-amino-1-phenyl-2-pyrazolin-5-one in benzene in the presence of PTSA afforded 4-(2-hydroxyphenyl)-2,3a,4,4a-tetrahydro-2-phenylindeno[ 1,2-ḇ]pyrazolo[4,3-e̱]pyridine-3,5-dione (6a). However, the condensation of la with 2-amino-4,6-dihydroxypyrimidine gave the dimeric structure 7. The structures of the hitherto unknown ring systems have been confirmed by PMR, IR and mass spectral data

Influence of Zn−Cr catalyst on the liquefaction of coal in methanol

It has been established that the catalytic effect of Zn−Cr catalysts on coal liquefaction in methanol is due to the hydrogenation of coal and its liquefaction products by dihydrogen. The latter is formed by catalytic decomposition of methanol. Impregnated catalysts are more active than unsupported ones. Quantitative processing of PMR data indicated that during liquefaction methanol intensively alkylates the organic mass of coal and or/the liquid products.

Conversion of pyridoxine into 6-hydroxypyridoxine by food components, especially ascorbic acid.

In experiments designed to examine interactions between pyridoxine (PN) and food components, PN was found to be converted into an unidentified compound in the presence of the homogenates of various plant foods under mild conditions. The formation of the compound tended to be higher when food samples had a higher ascorbic acid (AsA) content. The reaction was neither thermal decomposition nor photodecomposition. This compound was also formed by incubating PN with AsA in the dark. Conversion of PN into the compound proceeded with oxidation of AsA, and was negligible under anaerobic conditions. The pH optimum for the reaction was between 4 and 7, and the temperature optimum was between 30 and 50 degrees C. The compound was purified by ion-exchange chromatography, isolated as colorless needles, and identified as 6-hydroxypyridoxine from UV, PMR, IR and MS spectral data. 6-Hydroxypyridoxine had neither vitamin B6 nor antivitamin B6 activity for Saccharomyces carlsbergensis 4228 (ATCC 9080). From these results, we inferred that hydroxylation of PN in the presence of food components, especially AsA, caused loss of vitamin B6 in plant foods during food processing, storage and cooking.

Structure and nuclear magnetic resonance spectra of 6-bromo-3,3′,4′,5,7-penta-O-methylcatechin

The title compound has been synthesized by selective debromination of 6,8-dibromocatechin and indirect methylation of the resulting 6-bromocatechin via its pentaacetate. The structure of C20H23BrO6 has been determined by X-ray crystallography. The compound crystallizes in the space group P1 with a = 9.589(3) Å, b = 11.576(3) Å, c = 11.326(3) Å, α = 118.80(3)°, β = 93.23(3)°, γ = 111.44(3)°, ρc = 1.481 g cm−3, and Z = 2. Intensities were measured for 2584 independent reflections (2θ < 45°) of which 2213 were observed (I > 3.0σ(I)) and used in subsequent refinement (final R values were R = 0.0268 and Rw = 0.0344). Crystallographic and pmr data confirm the position of the bromine atom at C-6, the trans-diaxial arrangement of H-2/H-3 and the quasi-equatorial orientation of the 3,4-dimethoxyphenyl group (ring B). The two heterocyclic ring conformations are consistent with the expected flexibility of the molecule.

Aryl-(9-m-carboranyl)halonium salts

The authors report the synthesis of a number of new aryl-(9-m-carboranyl)halonium compounds, in which the benzene ring contains a substituent in addition to the carboranylhalonium group. The applicability of the diazo method for carboranes is demonstrated and the general nature of t his reaction in the synthesis of phenyl-(9-m-carboranyl)chloronium tetrafluoroboride. The reactions of aryldiazonium salts with halocarboranes led to a mixture of trifluoroacetic acid and hexafluorobenzene. Upon using hexafluorobenzene as a cosolvent, halocarboranes are completely dissolved upon heating and the action mixture becomes homogeneous, resulting in much higher yields of the carboranylhalonium salts. The yields, PMR data, and elemental analysis results are presented.

Configuration et conformation d'un diastéréoisomère du diphinyl-3,5 hydroxy-2 tétrahydrothiophène carboxylate-2 d'éthyle. Déplacements chimiques induits en RMN du proton par Eu(fod) 3

The condensation between thioglycolic ethyl ester and benzylideneacetophenone is stereoselective and gives only one of the four hydroxythiophanic diastercoisomers. Analysis of i.r. and PMR data is unable to give precisely its configuration and its major conformer. A computer analysis of PMR-LIS data (solution), using the Newton non-linear least-squares algorithm, only shows the conformer present in the solid state.

Nematic Order in Polyesters with Flexible Moieties in the Main Chain

Properties of polyesters based on 4,4′-dihydroxy-2,2′-dimethylazoxybenzene and a homologous series of alkanedioic acids with methylene sequence length n=3—4 are discussed in the light of recent results based on DSC, PMR, magnetic birefringence and X-ray data. Influence of substitution in the mesogen and spacer is also described. Particular attention is given to the oddeven effect in the homologous series and the existence of two distinct levels of molecular order for the n=even and n=odd members of the series. On the basis of X-ray diffraction data performed on oriented samples, a cybotactic micellar model for the n=even polymers is proposed. The cooperative nature of the formation of cybotactic micelles is shown by the study of order parameter and its dependence on the degree of polymerization. Progressive development of layered order in n=even polymers with increase in molecular mass is also shown by SAX patterns of unoriented samples of poly(4,4′-dioxy-2,2′-dimethylazoxybenzenedodecanedioyl). While the Meier and Saupe theory of the nematic state is in good agreement with the S(T) dependence for noncybotactic polymer systems for most of the nematic interval, it diverges in the vicinity of the clearing point. In contrast to low molecular mass nematics, polymeric nematics show a remarkable stability at the clearing temperature and a large pretransitional interval.

Novel chelated compounds of β-carbobutoxyethyltin trichloride

This paper reports the synthesis and replacement reactions of β-carbobutoxyethyltin trichloride in continuation with our earlier work on β-carboalkoxyethyltin compounds [1-3]. The bidentate ligands used for replacement were acetylacetone, salicylaldehyde, dibenzoylmethane, 2-hydroxy-4-methoxy-benzophenone, 8-hydroxyquinoline, benzoylphenyl-hydroxylamine and salazine. The stepwise replacement reactions of β-carbobutoxyethyltin trichloride were also carried out and products well characterized on the basis of their elemental analysis, infrared and PMR data. These compounds are monomeric in boiling benzene.

A study of the diels-alder reaction of 3-oxabicyclo[3.3.0]oct-1(5)-ene-2,4-dione with cyclopentadiene and some related dienes

The reaction of 3-oxabicyclo[3.3.0]oct-l(5)ene-2,4-dione, 2, with cyclopentadiene, 3, 5,5-diethoxycyclopentadiene, 4, and 6,6-dimethylfulvene, 5, is studied. Reaction of 2 and 3 yields the expected endo-adduct, while reaction of 2 and 5 gives a mixture of the endo- and exo-adducts whose ratio is slightly dependent on the reaction conditions. Attractive electrostatic interactions in the transition state leading to the exo-adduct can explain the absence of endo stereoselectivity in the last reaction. Steric factors seem to be responsible for the absence of reaction between 2 and 4. The analysis of the 13C NMR spectra of these adducts and some derived compounds confirms the tentative configuration assignment carried out on the basis of PMR data. Also, the synthesis of dimethyl(1R,2S,6R,7S)-10-oxotricy-clo [5.2.1.0 2.6]decane2,6-decarboxylate, 1, from the endo-adduct of the reaction of 2 and 5, is described

SYNTHESIS OF NOVEL TYPES OF 2-SUBSTITUTED-MERCAPTO-7,8-DIMETHYLPYRANO[2,3-e]BENZOXAZOL-6(H)-ONES

Abstract 7-Hydroxy-2,3-dimethylchromone (Ia) on nitration followed by reduction of the resultant 8-nitro-7-hydroxy-2,3-dimethylchromone (Ib) affords 8-amino-7-hydroxy-2,3-dimethylchromone (Ic). Reaction of (Ic) with CS2 in alkaline medium furnishes 2-mercapto-7,8-dimethylpyrano-[2,3-e]benzoxazole-6(H)-one (IIa) which on treatment with alkylhalides and acid halides gives the corresponding thioethers II(b-f) and thioesters II(g-i), respectively, which have been confirmed on the basis of elemental analysis, IR, PMR and mass spectral data.

STUDIES ON 2-MERCAPTO COUMARINOXAZOLE SYSTEMS: SYNTHESIS OF NOVEL TYPES OF 2-MERCAPTO-9-METHYL-7H-PYRANO-(3,2-e)BENZOXAZOLE-7-ONE DERIVATIVES—PART III

Abstract 5-Amino-6-hydroxy-4-methylcoumarin (I) when treated with carbon disulphide in alkaline medium to furnish the novel and hitherto unknown 2-mercapto-9-methyl-7H-pyrano(3,2-e)benzoxazole-7-one (IIa). Treatment of IIa with alkyl halides and acid halides gives the corresponding thioethers (IIb-i) and thioesters (IIj-k) respectively. Oxidation of IIb, IIc, IId, IIf, IIh with hydrogenperoxide gives the corresponding sulfones (IIIa-e). These are characterised by elemental analysis, IR, PMR and mass spectral data.

ChemInform Abstract: 3-METHYL(1,3,4)THIADIAZINO(2,3-B)QUINAZOLIN-6-ONES

Die Titelverbindung (V) wird aus dem Chinazolinon (I) und Allylbromid (II) über die Stufen (III) und (IV) synthetisiert.

Alkylammonium dialkylarsiante surfactants in organic solvents: Aggregation and water solubilization studies

The aggregation of butyl-, octyl-, and dodecylammonium di-2-ethylhexylarsinate in C 6D 6, CDCl 3, and CCl 4 was studied by PMR spectroscopy. The variation of the chemical shifts of the magnetically discrete protons as a function of the stoichiometric concentration of the surfactants indicates that the − N + H 3 and −AsO 2 − ions are located at the aggregate interior. A multiple equilibrium aggregation model was applied to the PMR data, the equilibrium constant for aggregation, and the aggregates distribution calculated. Both quantities depend on the chain length of the alkylammonium moiety, and on the solvent polarity. Compared to the corresponding alkylammonium diethylarsinates the title surfactants show higher aggregation tendency, probably due to the diminished solvent-head-ions interactions. The polarity (Z value) of the water solubilized by dodecylammonium dietyl-, and di-2-ethylhexylarsinates in chloroform showed marked dependence on the [water]/[surfactant] ratio. Higher Z values were obtained in the case of the latter surfactant, reflecting weaker interactions of the head-ions with the solubilized water. The obtained Z values indicate micellar cores whose polarities lie between those of dichloromethane, and acetonitrile or t-butanol.

Copolymerization of 1-vinyl-1,2,4-triazole with methyl methacrylate and stryrene

The authors have investigated the copolymerization of 1-vinyl-1,2,4-triazole (VT) with methyl methacrylate (MMA) and styrene. From the data on the composition of the copolymers and mixture of monomers by the Fineman-Ross and Kelen-Tüdos techniques they find the values of the relative copolymerization constants. For the system VT-MMA they oolution the values r 1 = 0·62±0·02 and r 2 = 1·48±0·08; for VT -styrene r 1 = 0·32±0·08, r 2 = 1·4±0·1. From the PMR data they evaluate the value of the Taft constant σ R for VT. The reduced activity of VT in copolymerization as compared with MMA and styrene is explained by the polarization of the vinyl bond by the 1,2,4-triazolyl radical.