A pyridine-based

Contains Nitrogen.—First test the original solid ni liquid by heating in a hard-glass tube with soda-lime (p. 2), and notice if the smell is that of ammonia (ammonia salt, amide or cyanide), an amine (amine or amino-acid) or a pyridine base (alkaloid). 

The solvent system N2O4/DMF has been employed for the preparation of inorganic esters, e.g., phosphates and sulfates [221] as well as organic esters. The latter products were obtained by reacting the polymer with acyl chlorides, or acid anhydrides in the presence of a pyridine base. The nitrite ester formed has been successfully trans-esterified by the reaction with RCOCl... 

A milder protocol for the conversion to enones involves use of a catalytic amount of TMSOTf and a pyridine base.47... 

Scheme 2. Traceless linkers for the solid-phase synthesis of (a) pyridine-based tricycles and (b) isoquinolines.

In the medium pH range where both the diazenium cation and the diazene exist in solution, these two species react rapidly to afford a substituted tetrazene [141], The second oxidation wave, observed for disubstituted hydrazenes in acetonitrile with a pyridine base present, is due to the further oxidation of the tetrazene to a dicationic species. 

Carboxylation of dienes and trienes, which takes place in a stepwise fashion, affords mono- or dicarboxylated products.146 Cobalt carbonyl,147 palladium chloride,148 149 and palladium complexes150 were used. 1,4 Addition to 1,3-butadiene gives the corresponding unsaturated tram ester (methyl trans-3-pentenoate) in the presence of [Co(CO)4]2 and a pyridine base.147 The second carboxylation step requires higher temperature than the first one to yield dimethyl adipate. In a direct synthesis (110°C, 500 atm, then 200°C, 530 atm) 51% selectivity was achieved.147... 

A very large number of chlorates are known and they may be divided into inorg org chlorates. Inorg chlorates of alk or alkaline earth metals are prepd either by action of chlorine on hot alkali or by electroytic oxidn of the chloride ion. For the prepn of org chlorates, such as pyridine chlorate, a pyridine base is treated with an aq soln of HC103< Kirk Othmer(Ref 8), Gmelin(Ref 3) others describe various methods of prepg chlorates. See also under various chlorate compds described below... 

A pyridine base is used to neutralize the hydrochloride in order to free the semicarbazide so it may react with the carbonyl substrate. 

The addition of pyridine bases to [Co(III)(H20)(CN)(BDHC)]+ in aqueous media results in a spectral change that can be attributed to substitution of the coordinated water by a pyridine base. This substitution is represented in the following equation and equilibrium. 

Metal Ion Effect Complexation of PMPS with Zn2+ ion could be observed by the decrease of absorption intensity of the pyridine ring (Figure 20b). A similar decrease was observed for the parent pyridyl-methylphosphonate (Figure 20b). Therefore, the 1 1 complex in which a metal ion is bridged between pyridyl nitrogen and phosphoryl oxyan-ion likely is involved (Figure 16a). Meanwhile, no detectable change of spectrum was observed in the case of Mg2+ ion, in accordance with very weak chelation of Mg2+ ion with a pyridine base. 

From their standard reduction potentials, in the range of 1.35 V versus NHE [37], complexes should not be able to oxidize methylbenzenes, the standard potentials of which exceed 1.75 V versus NHE [29]. The reaction, however, proceeds easily in the presence of a pyridine base, according to the following stoichiometry ... 

Oxidation of coniine with chromic acid produces butyric acid (115, 124), while dehydrogenation of the alkaloid with silver acetate converts it to abase, conyrine (125), which is also obtained from coniine hydrochloride by distillation with zinc dust (126). Conyrine, CgHnN, is a colorless, fluorescent oil, b.p. 166-168°, which forms a chloroplatinate and an aurichloride it can be converted back to coniine by reduction with hydriodic acid, it behaves on methylation like a pyridine base, and further, it gives rise on oxidation to a-pyridinecarboxylic acid. Therefore, conyrine is a 2-propylpyridine (XCIV) while coniine is a 2-propylpiperidine (XCV) (126), in which the side chain is normal since conyrine is not identical with 2-isopropylpyridine (127). 

Nicotinamide l,iV -ethenoadenine dinucleotide, prepared from NAD+ and chloroacetaldehyde, has been converted into 3-aminopyridine l,A -etheno-adenine dinucleotide (4) by a pyridine base exchange reaction which was catalysed by the venom of Bungarus fasciatus. Yeast alcohol dehydrogenase was... 

The first immobilization of a pyridine-based tridentate ligand has also been investigated since the tridentate ean stabilize the zinc complex and reduce the effect of the polymer blackbone [140]. The aminoaleohol 207 was prepared in six steps from 2,5-dibromopyridine and was anchored onto a 2% DVB crosslinked Merrifield resin to afford the supported-tridentate ligand 208 (Seheme 85). This immobilized ligand was then employed in the diethylzinc addition to benzaldehyde and the excellent catalytic activity was recorded when the reaction was carried out in toluene at rt using 5 mol% of catalyst and a low benzaldehyde/Et2Zn ratio of 1/1.1 (>99% conversion and 93% ee). 

Ma et al. [80] designed a pyridine-based diamine monomer, namely, 4-phenyl-2,6- j5(3-[4 -amino-2 -trifluoromethyl-phenoxy]phenyl)pyridine, to improve the thermal and chemical stability of the polyimides at high temperature. A representative structure of the polyimide with ODPA as a dianhydride unit is shown in 3-73 (in Table 3.4). The Tg of the polyimide was reported to be 187 °C with a Tj 5% as high as 532 °C in air. The TS of the polyimide was recorded at 97 MPa and the EB at 11%, indicating the strong and tough nature of the polyimide. 

Warycha, S. Vapour pressures and excess Gibbs energies in mixtures of a pyridine base + 2-propanol, + 2-butanol, + i-butanol, and + t-butanol at 313.15 K 7. Chem. Thermodyn. 1977,9, 813-820... 

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