4-Hydroxycoumarin/2-hydroxychromone tautomerism: Infrared spectra of 3-substituted-2-13c-4-hydroxycoumarins

By isotopic replacement of the carbonyl carbon with ¹³C, the C?O stretching frequency was identified as the highest frequency strongly absorbing band in the 1550–1750 cm^?1 region of the infrared spectra of several 3-substituted 4-hydroxycoumarins and 3-substituted 4-alkoxycoumarins. The compounds selected for study were either known to crystallize as the coumarin tautomeric form by x-ray diffraction studies or were congeners of such compounds. The carbonyl band varied from 1664 cm^?1 in inter- or intramolecularly hydrogen bonded derivatives to 1718 cm^?1.     

Infrared spectra of 2- and 3-furylmercuric chloride

The i.r. spectra of solutions of 2- and 3-furylmercuric chloride have been measured in the range 200–1600 cm⁻¹, and vibrational frequencies have been assigned.     

Infrared spectra of the Cl- -C2H4 and Br- -C2H4 anion dimers

Infrared spectra of mass-selected Cl- -C2H4 and Br- -C2H4 complexes are recorded in the vicinity of the ethylene CH stretching vibrations (2700-3300 cm(-1) using vibrational predissociation spectroscopy. Spectra of both complexes exhibit 6 prominent peaks in the CH stretch region. Comparison with calculated frequencies reveal that the 4 higher frequency bands are associated with CH stretching modes of the C2H4 subunit, while the 2 weaker bands are assigned as overtone or combinations bands gaining intensity through interaction with the CH stretches. Ab initio calculations at the MP2/aug-cc-pVDZ level suggest that C2H4 preferentially forms a single linear H-bond with Cl- and Br- although a planar bifurcated configuration lies only slightly higher in energy (by 110 and 16 cm(-1), respectively). One-dimensional potential energy curves describing the in-plane intermolecular bending motion are developed which are used to determine the corresponding vibrational energies and wavefunctions. Experimental and theoretical results suggest that in their ground vibrational state the Cl- -C2H4 and Br- -C2H4 complexes are localized in the single H-bonded configuration, but that with the addition of modest amounts of internal energy, the in-plane bending wavefunction also has significant amplitude in the bifurcated structure.     

Synthesis of 3-(α-naphthylmethyl)-4-hydroxycoumarin and its derivatives

3-(α-Naphthylmethyl)-4-hydroxycoumarin and a series of derivatives are prepared by condensing phenols with diethyl α -naphthylmethylmalonate under the influence of heat.     

Study of the tautomerism of 4- and 2- carbalkoxy-3-thiophanones

The equilibrium positions of 4-carbomethoxy-3-thiophanone (I), 2-carbomethoxy-4-methyl-3-thiophanone (II), 4,5-dicarbomethoxy-3-thiophanone (III), and 4-carbethoxy-5-phenyl-3-thiophanone (IV) in acetonitrile, dioxane, and alcohols was determined. The Meyer equation is satisfied for ketones I and II paired with acetylacetone and for III and IV paired with methyl cyclopentanone-2-carboxylate in alcohol solutions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1473–1480, November, 1971.     

Prototropic tautomerism and absorption spectra of substituted 4-hydroxyhexahydropyrimidinethiones-2

The IR and UV absorption spectra of the products of reaction of certain -isothiocyanoketones with ammonia, primary, and secondary amines are studied. It is shown that ammonia and primary amines usually give substituted 4-hydroxyhexahydropyrimidinethiones-2, which in the solid state are involved in intermolecular association due to hydrogen bonding. Solutions of these compounds exhibit ring-chain tautomerism equilibrium between a cyclic hydroxy form and an acyclic oxo form related to the class of oxoalkylthioureas. The reaction products both from -isothiocyanoketones and secondary amines, are substituted thioureas, both in the crystalline state and in solution. All the substances studied have a thione structure.     

Solid state13C NMR spectra and intermolecular tautomerism of 4-arylazo-1-naphthols

The¹³C NMR spectral data obtained for 4-(p-nitrophenyl)azo-1-naphthol in the solid phase are presented. The intermolecular mechanism of the azoquinonehydrazone tautomerism in compounds of a similar type is examined.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2302–2308, October, 1991.     

Infrared spectra and theoretical study ofE-3-(2-R-vinyl)-2-benzothiazolinones

The C=O stretching frequencies ofE-3-(2-R-vinyl)-2-benzothiazolinones (1 a–1 p) were measured in CCl₄ and CHCl₃ and correlated with ⁺ and * substituent constants. Thev(C=O) vs * (R) correlation was compared to an analogical relationship obtained with 3-R-2-benzothiazolinones (2). The electronic structure and geometry of compounds was investigated by CNDO/2 and PCILO methods. The results of both the spectral and theoretical studies showed forE-3-(2-R-vinyl)-2-benzothiazolinones a preference of the N—C-s-cis conformation (3), in which the substituent effects are transmitted to the C=O group very efficiently. The transmission factor for the CH=CH group was determined according to the definition ofJaffé. The role of inductive effects, delocalization of the nitrogen lone-pair electrons as well as the through-space interaction between the C=O and C=C bonds is discussed in terms of transmission mechanism and structural properties.

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Infrarotspektren und theoretische Untersuchungen vonE-3-(2-R-vinyl)-2-benzo-thiazolinonen

Zusammenfassung Es wurden die C=O-Streckfrequenzen vonE-3-(2-R-vinyl)-2-benzothiazolinonen (1 a–1 p) in CCl₄ und CHCl₃ gemessen und mit -, ⁺- und *-Substitutionskonstanten korreliert. Diev(C=O)-*-Korrelation wurde mit einer analogen Beziehung für 3-R-Benzothiazolinonen (2) verglichen. Die elektronische Struktur und die Geometrie der Verbindungen wurden mittels CNDO/2- und PCILO-Berechnungen untersucht. Es ergab sich dabei sowohl aus den spektros-kopischen als auch aus den theoretischen Ergebnissen eine N—C-s-cis-Konformation (3) für dieE-3-(2-R-vinyl)-2-benzothiazolinone, da dies eine günstige Geometrie zur Übermittlung von Substitutionseffekten zur C=O-Gruppe ergibt. Der Transmissionsfaktor für die CH=CH-Gruppe wurde nach der Definition vonJaffé bestimmt. Die Rolle von induktiven Effekten, der Delokalisierung des freien Elektronenpaares am Stickstoff und der C=O....C=C-Wechselwirkungen durch den Raum wurde auf Basis von Transmissionsmechanismen und strukturellen Eigenschaften diskutiert.

     

Keto-enol tautomerism of 4-hydroxy-3-phenyl-2-(2-chloroacetamidophenyl)-1-isoquinolone

Three crystalline modifications of the N-chloroacetyl derivative were obtained in the chloroacetylation of 2-(2-aminophenyl)-4-hydroxy-3-phenyl-1-isoquinolone. It was established by IR spectroscopy that they differ with respect to isomeric composition and the character of the intermolecular hydrogen bonds. For the first time, both keto-enol tautomeric forms were isolated in individual form in the 4-hydroxy-1-isoquinolone series.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 542–543, April, 1985.     

A 1H and 13c Nmr study of the structure and tautomerism of 4-pyrazolylpyrazolinones

It has been established that the primary reactions products between dehydroacetic acid and p-chlorophenylhydrazine or 4-phenylthiazol-2-ylhydrazine are 4-acetylacetyl-5-hydroxypyrazoles. These compounds react with the above hydrazines to yield 4-(pyrazol-5′-yl)-2-pyrazolin-5-ones which exist in solution as 5-hydroxypyrazoles.     

1H and 13c NMR spectra of 8- hydroxyquinoline

The ¹H and ¹³C NMR spectra of 8-hydroxyquinoline were analyzed. The assignment of the signals was established unambiguously by ¹³C-{¹H} double-resonance experiments and investigation of the ¹³C NMR spectrum without decoupling from the protons.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1235–1236, September, 1977.     

Proton-coupled 13C NMR spectra of 2- and 3-substituted pyridines

The proton-coupled ¹³C NMR and PMR spectra of pyridine and the 2- and 3-monosubstituted pyridines NC₅H₄X [where X=CH₃, CN, COCH₃, COOCH₃, N(CH₃)₂, NO₂, OCH₃, Cl, or Br] for one-molar solutions of the compounds in DMSO-D₆, have been analyzed. The signs and values of the ¹³C-¹H HSSCs have been determined. Equations have been obtained connecting the ¹³C-¹H SSCCs in the 2- and 3-substituted pyridines and the monosubstituted benzenes. A satisfactory correlation of ¹JCH with the F and R constants of the substituents has been shown.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1223–1230, September, 1984.     

Synthesis and certain conversions of 3-(3,3-dichloroallyl)-4-hydroxycoumarin

A method has been developed for the synthesis of 3-(3,3-dichloroallyl)-4-hydroxycoumarin and 2-thioxo-3-(3,3-dichloroallyl)-4-hydroxy-2H-chromene, and certain conversions of these compounds have been studied. They undergo acid hydrolysis readily, forming (respectively) 3-(4-hydroxy-3-coumarin)- and 3-(2-thioxo-4-hydroxy-2H-chromene-3)propionic acids; these compounds are converted to the corresponding lactones by the action of acetic anhydride.Erevan State University, Erevan 375049. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 48–51, January, 1997.     

Infrared spectra of ethylene clusters: (C2D4)2 and (C2D4)3

Spectra of ethylene dimers and trimers are studied in the ν(11) fundamental band region of C(2)D(4) (≈2200 cm(-1)) using a tuneable quantum cascade laser to probe a pulsed supersonic slit jet expansion. The dimer spectrum is that of a prolate symmetric top perpendicular band, with a distinctive appearance because the A rotational constant is almost exactly equal to six times the B constant. The analysis supports the previously determined cross-shaped dimer structure with D(2d) symmetry. An ethylene trimer has not previously been observed with rotational resolution. The spectrum is that of an oblate symmetric top parallel band. It leads to a proposed trimer structure which is barrel shaped and has C(3h) or C(3) symmetry, with the ethylene monomer C-C axes approximately aligned along the trimer symmetry axis.     

13C NMR spectra and azoquinone hydrazone tautomerism of azo-2-naphthols and azo-1-naphthols

Conclusions The¹³C NMR spectra of 1-phenylazo-2-naphthols and 2-phenylazo-1-naphthols have been investigated. For both classes the azoquinone hydrazone tautomeric equilibrium is shifted as a result of the nature of the substituent in the benzene ring and a qualitative series of effects has been established. A quantitative measurement of the tautomer composition has been obtained for the arylazo-2-naphthols.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2271–2277, October, 1988.The authors thank M. V. Gorelika for submitting samples for investigation and for an interesting discussion.     

Vibrational spectra of succinonitrile and its [1,4-13C2]-,[2,2,3,3,-2H4]- and 1,4-13C-2,2,3,3-2H4]-isotopomers and a force field of succinonitrile

[1,4-13C2]-succinonitrile, [2,2,3,3-2H4]-succinonitrile, [1,4-13C2-2,2,3,3-2H4]-succinonitrile have been synthesized and, for the first time, the infrared and Raman spectra of these succinonitrile isotopomers have been discussed in detail. The spectra were recorded at ambient temperature and at the temperature of liquid nitrogen and assignments of the vibrational bands of all above isotopomers have been made. In addition to this, the force field of succinonitrile in its two configurations, gauche and trans, have been calculated using all experimental frequencies and the ab-initio method. Also, the assignments of the vibrational bands of the 'normal' succinonitrile molecule have been achieved using the results of the force field calculations to support the assignments for the normal succinonitrile, as well as for the isotopomers.     

固体超强酸SO2-4/SnO2-Al2O3的红外光谱研究

以四氯化锡、硫酸铝为原料,氨水为沉淀剂,采用共沉淀法制得新型固体超强酸SO2-4/SnO2-Al2O3.采用FT-IR技术考察了金属元素摩尔比、焙烧温度、浸渍液以及掺杂稀土氧化物对该固体超强酸结构和性能的影响.FT-IR结果表明在该固体超强酸中,锡和硫酸根是以螯合和桥式两种方式配位结合,其中起催化活化作用的主要是和硫酸根以螯合双齿结合的锡;和SO2-4/ZrO2型超强酸相比,SO2-4/SnO2-Al2O3超强酸的硫酸根FT-IR特征吸收峰发生蓝移,显示出更强的酸性.锡铝摩尔比为9∶1、焙烧温度为773K、焙烧时间为3h时,制得的SO2-4/SnO2-Al2O3样品对酯化反应的催化性能最好.     

13C NMR spectra of some 1-, 3- and 4-monosubstituted and disubstituted isoquinolines

Chemical shifts and substituent chemical shift (SCS) effects are reported for 21 monosubstituted iso-quinolines, carrying a halogeno, amino, piperidino or ethoxy group in position 1, 3 or 4. In some cases, assignments of ¹³C resonances were based on the spectra of the corresponding 5-deutero derivatives. For the fluoroisoquinolines some ¹³CF coupling constants are given. The ¹³C NMR spectra of 15 disubstituted isoquinolines were measured; with a few exceptions, mainly the 3,4- and 1,4-disubstituted isoquinolines, the chemical shifts agreed well with those calculated by addition of the SCS effects.     

The preparation,spectra and tautomerism of some 4(n-arylamino)-1,2-naphthoquinones

Twelve 4(N-arylamino)-1,2-naphthoquinones (1) have been prepared by the direct addition of substituted anilines to 1,2-naphthoquinone, and their spectra have been studied. In the solid and in ethanol solution the 1,2-naphthoquinone tautomer (1a) predominates, but in trifluoroacetic acid the 2-hydroxy-1,4-naphthoquinone-4-aryliminium (2a) is the major species.