The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Chemistry of vitamin B6. IX. Derivatives of 5-deoxypyridoxine》. Authors are Heyl, Dorothea; Harris, Stanton A.; Folkers, Karl.The article about the compound:5-(hydroxymethyl)-2,4-dimethylpyridin-3-ol hydrochloridecas:148-51-6,SMILESS:OC1=C(C)C(CO)=CN=C1C.[H]Cl).Product Details of 148-51-6. Through the article, more information about this compound (cas:148-51-6) is conveyed.
cf. C.A. 47, 8745g. The 5-deoxy derivatives (I) of pyridoxine (II), pyridoxal (III), and pyridoxamine (IV) were prepared and characterized. The I can participate normally in biochemical reactions involving the substituent at the 4-position but cannot be phosphorylated like II, III, and IV. As expected the I had no vitamin B6 activity but were effective antimetabolites. Codecarboxylase has been catalytically hydrogenated to 5-deoxypyridoxine (V); both II and III yielded under the same conditions a mixture of 4-deoxypyridoxine (VI) and V. The absorption spectra of 5-deoxypyridoxal (VII) (recorded) and pure pyridoxal-5-phosphate (codecarboxylase) (VIII) at pH 11.0 and 1.9, resp., are almost identical. The deep yellow color of both VII and VIII in alk. solution together with other absorption characteristics is ascribed to a quinoid structure. 2-Methyl-3-hydroxy-4-methoxymethyl-5-chloromethylpyridine (IX).HCl (2.38 g.) in 125 cc. MeOH was shaken with H in the presence of 2 g. 5% Pd-Darco, the mixture filtered, and the filtrate concentrated to 20 cc. to yield 1.5 g. (75%) 2,5-dimethyl-3-hydroxy-4-methoxymethylpyridine (X).HCl, m. 152-3° (from EtOH-Et2O). IX.HCl (23.7 g.) reduced similarly in 2 equal portions, each one in 600 cc. MeOH with 5 g. Pd catalyst yielded 19.0 g. (94%) X.HCl. X.HCl (1.47 g.) in 50 cc. 4N HCl heated 3 hrs. at 180-90° in a sealed tube, the colorless solution filtered, the filtrate concentrated to dryness, and the H2O removed azeotropically with EtOH and C6H6 yielded 0.96 g. (70%) V.HCl, m. 143-3.5° (from EtOH-Et2O); treated with excess NaHCO3 gave V, m. 181-2° (from EtOH). X.HCl was treated in H2O with NaHCO3, the mixture concentrated in vacuo and extracted with Et2O, the extract evaporated, 3.1 g. of the residual free base heated 18 hrs. with 50 cc. MeOH and 50 cc. liquid NH3 in a sealed tube, the mixture evaporated in vacuo to dryness, MeOH added and removed twice by distillation, and the residue extracted with Et2O to leave 1.86 g. (60%) 5-deoxypyridoxamine (XI); m. 160-1° (from MeOH); 2,5-dimethyl-3-p-toluenesulfonoxy-4-p-toluenesulfonylaminopyridine-HCl, m. 194-5° (from EtOH). A small sample of XI was heated 20 min. with Ac2O on a steam bath, the solution concentrated to dryness, the residue treated with EtOH, distilled to dryness, dissolved in HCl, treated with Darco, neutralized with NaHCO3, chilled, and the crystalline deposit recrystallized from C6H6 containing a few drops EtOH to give 2,5-dimethyl-3-acetoxy-4-acetylaminomethylpyridine, m. 174-5°. V.HCl (5.7 g.) was stirred 2 hrs. at 60-70° with 2.8 g. MnO2, 1.5 cc. H2SO4, and 75 cc. H2O, the mixture filtered, the filtrate concentrated in vacuo, the sirup taken up in 15 cc. H2O, excess solid AcONa added, and the thick, crystalline precipitate cooled, filtered off, and washed with ice water to give 1.30 g. (29%) VII, m. 108-9° (from petr. ether); the aqueous filtrate from VII gave with 2 g. NH2OH.HCl 0.9 g. (18%) oxime of VII, m. 239-40° (decomposition) (from EtOH). To the aqueous filtrate of a similar run were added 12 g. NaOAc and 4.5 g. NH2OH.HCl and the mixture was heated 10 min. on a steam bath to yield 2.43 g. (49%) oxime of VII. VII in CHCl3 treated with excess alc. HCl, the solution evaporated in vacuo to dryness, a little H2O added and removed in vacuo, and the residue treated with CHCl3 yielded VII.HCl, m. 191-3° (decomposition). VII (90 mg.) in 1 cc. H2O was cooled in ice, the pH adjusted to 11 with 6N NaOH, 4 drops 30% H2O2 added, the mixture adjusted to pH 3 with HCl and cooled, and the precipitate washed with H2O, EtOH, and Et2O to yield 70 mg. (85%) 2,5-dimethyl-3,4-dihydroxypyridine, decomposed 262-70°. Crude Ca codecarboxylase (0.5 g.) was suspended in H2O and treated with 0.7 cc. 6N HCl, the mixture filtered, the filtrate diluted to 50 cc. shaken 2.25 hrs. at atm. pressure with H and 0.5 g. 10% Pd-C, filtered and concentrated to dryness in vacuo, the residue dissolved in about 3 cc. H2O, the solution treated with excess solid NaHCO3, filtered, the filter residue washed with H2O, the combined filtrate and washings were concentrated in vacuo to 5 cc., the concentrate extracted 21 hrs. continuously with CHCl3, the extract evaporated, and the residue treated with alc. HCl and precipitated with Et2O to give 0.07 g. V.HCl, m. 140-1°. III.HCl (0.35 g.) was treated with 0.10 g. CaO and 0.17 g. H3PO4 and hydrogenated similarly to give 0.08 g. (24%) VI.HCl, m. 264-5°, and 0.11 g. (33%) V.HCl; the aqueous filtrate left from the CHCl3-extraction was concentrated to dryness, the residue extracted with EtOH, and the extract acidified with alc. HCl to give 0.11 g. (30%) I.HCl. Similar hydrogenation of 0.40 g. I.HCl in 0.3 cc. 6N HCl and 50 cc. H2O for 4-5 hrs. gave 0.16 g. (42%) VI.HCl and 0.09 g. (24%) V.HCl. Attempted similar hydrogenation of V gave only recovered starting material.
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Reference:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia