4- pyrida zines

A couple of examples of other heterocycles, a pyrazole and a pyrida-zine, are given in Scheme 5.58, with their fluorine, proton, and carbon NMR data. 

X-Ray crystallographic analysis of 4-(2,4-dinitrophenyl)-2,5-dioxo-8-phenyl-l,2,3,4,5,6-hexahydropyrido[2,3-semi-empirical molecular orbital calculation (AMI) <2000T2473>. 

With certain heteroaromatic compounds a different isomerization is found, in which a 1,3-transposition of atoms (rather than a 1,2-transposition of adjacent atoms) takes place. This is true for pyrida-zines(e.g. 3.24), and since the process is shown not to beasequence ol two independent 1,2-transpositions, a mechanism involving a... 

Some pyridazines were investigated by cyclic voltametry and/or preparative scale electrolysis to give mixtures of reduced compounds [77NKK990 81 ACS(B)185]. The half-wave potentials of some 3(27/)-py-ridazinones were determined at different pH and correlated with Hammett o--constants (77KGS668). Maleic hydrazide is stable, but reduced pyrida-zines undergo reductive N—N bond cleavage upon electroreduction (78-LA 1505). 

The synthesis of betaines of several aromatic azines and their benzologs by Katritzky et al. stimulated also investigations of the corresponding pyrida-zines. They were prepared by methylation of the corresponding pyridazinones with methyl toluene-p-sulfonate to 317 and subsequent conversion into betains (319). Contrary to other related betaines, compounds of the type 319 are unreactive toward a variety of dipolarophiles. The hydroxy form of the cation (317) was shown to (ncdominate over the oxo form (318). UV, IR, and NMR data have been used for structure examination of betaines (95) and some pyridazinones. NMR spectra established... 

Pyridazine forms a stable adduct with iodine, with semiconductor properties. " Similar complexes were prepared from iodine mono-ehloride, bromine, and nickel(II) ethyl xanthate. Complexes of pyrida-zines with iron carbonyls and with iron carbonyls and triphenylphosphine have been prepared and investigated. " Complexes of pyridazines with boron trihalides, silver salts, mercury(I) salts, iridium salts, " ruthenium salts, and chromium carbonyls are re-... 

Phthalazlne. 2,3-Benzodiazine benzo[d]pyrida-zine -phenodia/irie. C,H4N mol wt 130.14. C 73.83%, H 4.65%, N 21.53%. Prepd by reduction of 1-chlorophthala-zine with hy dr iodic acid and red phosphorus Gabriel,... 

The formation of cinnolines from heteromonocyclic systems other than pyrida-zine is rare. However, at least three such systems have been so used, as illustrated in the following examples. 

Scheme 53 Pd-catalyzed alkenylation of pyridine, pyrazine, quinoxaline, and pyrida-zine A/-oxides.

The preparation and reactions of some 7,7-diethylpyrazolo[l,2-a]pyrida-zine-6,8(7JT)dione derivatives (412) have been reported. ... 

Besides pyrimidine derivative, as to the best of our knowledge, only one example is described for another CFD. Janseen in 2008 described DoM reaction of pyrida-zine 1266 with LTMP followed by iodination affording iodo-derivative 1268 in 82 % preparative yield (Scheme 281) [724],... 

Which of following liquids will completely wet PET water (71.99), benzonitrile (35.79), pyrida-zine (49.51), glycerol (63.4), adiponitrile (45.5) and acetone (23.3) Explain briefly your answer. The numbers in parenthesis arc the surface tensions in mN m at 20 °C. 

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