Absorption spectra of some pyridine and pyridine N-oxide derivatives in oleum

The absorption spectra of a number of pyridlne and pyridine N-oxide derivatives in media of different acidity functions have been investigated. The bathochromic shift of the shortwave absorption band in oleum is interpreted as a consequence of the addition of a proton to the conjugate acid. The formation of a hydrogen bond between the 3-hydroxy derivative of the heterocyclic compounds investigated and the oleum, appearing as a hypsochromic shift of the long-wave absorption band, has been detected. This phenomenon is absent in the case of the 2-methoxy derivative.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 963–966, July, 1973.     

Synthesis of a new series of pyridine and fused pyridine derivatives

The reaction of 4-methyl-2-phenyl-1,2-dihydro-6-oxo-5-pyridine- carbonitrile (1) with arylidene malononitrile afforded isoquinoline derivatives 2a,b. 6-Chloro-4-methyl-2-phenyl-5-pyridinecarbonitile (3) obtained by chlorination of compound 1 with phosphoryl chloride was converted into 6-amino-4-methyl-2-phenyl-5-pyridinecarbonitrile (4) and 6-hydrazido-4-methyl-2-phenyl-5-pyridinecarbonitrile (5) in good yield, through reactions with ammonium acetate and hydrazine hydrate, respectively. Treatment of 4 with ethyl acetoacetate, acetic anhydride, formic acid, urea and thiourea gave the corresponding pyrido [2,3-d] pyrimidine derivatives 7-10a,b. A new series of 6-substituted-4-methyl-2-phenyl-5-pyridine carbonitriles 11-13 has been synthesized via reaction of 4 with phenyl isothiocyanate, benzenesulphonyl chloride and acetic anhydride. Treatment of 4 with malononitrile gave 1,8-naphthyridine derivative 14. The reactivity of hydrazide 5 towards acetic acid, phenylisothiocyanate and methylacrylate to give pyrazolo-[3,4-b]-pyridine derivatives 15-17 was studied. Treatment of 5 with acetic anhydride, phthalic anhydride and carbon disulphide gave pyridine derivatives 18,19 and 1,2,4-triazolo-[3,4-a]-pyridine derivative 20.     

Synthesis of propionamide pyridine and pyridine n‐oxide ligands

A new set of pyridine and pyridine N‐oxides functionalized with N,N‐dimethylpropionamide pendant groups in the 2‐ and 2,6‐positions have been prepared from the combination of 2‐chloromethylpyridine and 2,6‐bis(chloromethyl) pyridine with α‐lithio N,N‐dimethyl acetamide. The coordination interaction between 2‐(N,N‐dimethylpropionamide) pyridine N‐oxide ( 10 ) and Tb(NO₃)₃ has been unambiguously defined via single crystal X‐ray diffraction analysis of Tb( 10 )(NO₃)₃(H₂O).     

Photodissociation dynamics of pyridine

Photodissociation of pyridine, 2,6-d2-pyridine, and d5-pyridine at 193 and 248 nm was investigated separately using multimass ion imaging techniques. Six dissociation channels were observed at 193 nm, including C5NH5 --> C5NH4 + H (10%) and five ring opening dissociation channels, C5NH5 --> C4H4 + HCN, C5NH5 --> C3H3 + C2NH2, C5NH5 --> C2H4 +C3NH, C5NH5 --> C4NH2 + CH3 (14%), and C5NH5 --> C2H2 + C3NH3. Extensive H and D atom exchanges of 2,6-d2-pyridine prior to dissociation were observed. Photofragment translational energy distributions and dissociation rates indicate that dissociation occurs in the ground electronic state after internal conversion. The dissociation rate of pyridine excited by 248-nm photons was too slow to be measured, and the upper limit of the dissociation rate was estimated to be 2x10(3) s(-1). Comparisons with potential energies obtained from ab initio calculations and dissociation rates obtained from the Rice-Ramsperger-Kassel-Marcus theory have been made.     

Electrochemistry of pyridine derivatives

Journal of Solid State Electrochemistry - The uniqueness of electrochemistry lies in the fact that it can make an unequivocal contribution to the studies of redox reaction mechanisms as well as it...     

Pi-pi interaction in pyridine

pi-pi Interaction in pyridine dimer and trimer has been investigated in different geometries and orientations at the ab initio (HF, MP2) and DFT (B3LYP) levels of theory using various basis sets (6-31G, 6-31G, 6-311++G) and corrected for basis set superposition error (BSSE). While the HF and DFT calculations show the pyridine dimer and the trimer to be unstable with respect to the monomer, the MP2 calculations show them to be clearly stable, thus emphasizing the need to include electron correlation while determining stacking interaction in such systems. The calculated MP2/6-311++G binding energy (100% BSSE corrected) of the parallel-sandwich, antiparallel-sandwich, parallel-displaced, antiparallel-displaced, T-up and T-down geometries for pyridine dimer are 1.53, 3.05, 2.39, 3.97, 1.91, 1.47 kcal/mol, respectively. The results show the antiparallel-displaced geometry to be the most stable. The binding energies for the trimer in parallel-sandwich, antiparallel-sandwich, and antiparallel-displaced geometry are found to be 3.18, 6.14, and 8.04 kcal/mol, respectively.     

Microwave spectra of pyridine and monodeuterated pyridines. Revised molecular structure of pyridine

The microwave spectra of pyridine and its 2-D, 3-D and 4-D substituted species were reinvestigated. Nuclear quadrupole coupling and centrifugal distortion effects were considered also for the deuterated species resulting in improved values for the rotational constants of these species. Hereby more reliable information about the hydrogen positions could be obtained.     

Reductive dimerization of pyridine N-oxide

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 133–134, January, 1988.     

Reaction of hydridohydroxodecacarbo-nyltriangulotriosmium with pyridine

Conclusions The following occurs when HOs₃(OH)(CO)₁₀ is reacted with pyridine or deuteropyridine: replacement of both bridge ligands in the osmium cluster, cleavage of the C-H or C-D bond, and migration of the H or D atom into the metal ring.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2793–2794, December, 1981.     

Syntheses in the pyridine series

A new procedure for preparing 2-methyl-6-methoxy-4-thioquinolone (I), 2-methyl-7-chloro-4-thioquinoline (II), 2-thiopyridone (III) and 5-nitro-2-thiopyridone (IV) has been proposed. This involves the reactions of the corresponding halogen derivatives of quinoline and pyridine with sodium thiosulfate. Compounds I and II were synthesized for the first time.     

Syntheses in the pyridine series

It has been shown that when they are heated in 2 N caustic soda solution alkyl pyrid-2-yl sulfides are hydrolyzed at the Py-S bond with the formation of pyridones and the corresponding thiols. The latter were determined quantitatively by iodometric titration.For part VIII, see [1].     

Halogenation of pyridine 1-oxides

The chlorination and bromination of α-lithiopyridine 1-oxides has been studied. Only dihalogenated pyridine 1-oxides are formed. In the case of bromination dipyridyl derivatives are also formed, and, indeed, predominate. Chloromercuration of the lithiopyridine 1-oxides gave highly insoluble, unresolvable mixtures of pyridylmercury derivatives. These could be brominated readily to give mixtures of 2-bromo- and 2,6-dibromopyridine 1-oxides.     

Syntheses in the pyridine series

The conditions for obtaining some -dialkylaminoethyl pyrid-4-yl sulfide N¹-oxides and their quaternary salts have been studied. It has been shown that the addition of alkyl iodides to the bases obtained takes place in a similar manner to their addition to pyrid-4-yl sulfides not containing a N-oxide group.For part VII see [1]