The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Synthesis of vitamin B6 derivatives. Catalytic reduction of hydroxymethyl group substituted in pyridine ring》. Authors are Naito, Takeo; Ueno, Katsujiro.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).Category: pyrimidines. Through the article, more information about this compound (cas:148-51-6) is conveyed.
Catalytic reduction of 1.64 g. pyridoxine triacetate-HCl in 32 mL. H2O with 1 g. 10% Pd-C 1.5 h. at normal pressure of H absorbed 240 mL. H and gave 0.7 g. 3,4,6,5-Me3(OH)C5HN.HCl (I), m. 209-12°. Similarly, pyridoxine 4-Et ether HCl salt yielded 52% I, m. 210-12°. The above reaction with 1 mol absorption of H yielded 18% 4,6,3,5-Me2(HOCH2)(HO)C5HN.HCl (II), m. 250° (decomposition), and the mother liquor yielded 31% 3,6,4,5-Me2(EtOCH2)(HO)C5HN.HCl; picrate m. 138°. Catalytic reduction of 0.56 g. 6,3,4,5-Me(AcOCH2)(EtOCH2)(HO)C5HN.HCl in 20 mL. MeOH with 0.8 g. 10% Pd-C showed no absorption of H, the reduction proceeded well by addition of 20 mL. H2O and absorbed 54 mL. H in 2 h., and the product in 10% HCl heated 30 min. at 100° yielded 48.8% 3,6,4,5-Me2(EtOCH2)(HO)C5HN; picrate, m. 138°. Catalytic reduction of 3.76 g. pyridoxal oxime-HCl in 170 mL. H2O and 88 mL. 10% HCl with 4.8 g. 10% Pd-C absorbed 3050 mL. H in 20 h. and yielded 62% 3,6,4,5-Me2(HCl.H2NCH2)(HO)C5HN.HCl (III), m. 262-3° (decomposition); diacetate, C12H16O3N2, m. 176-7°; ditosylate-HCl, m. 194-5°. Catalytic reduction of 0.29 g. 6,3,4,5-Me(AcOCH2)(AcNHCH2)(AcO)C5HN in 8 mL. MeOH and 2.2 mL. 10% HCl-MeOH showed no absorption H but an addition of 10 mL. H2O absorbed 28 mL. H in 2 h. and yielded 100% diacetate of III, m. 174°. Similarly, 0.51 g. pyridoxal-HCl in 20 mL. H2O and 0.5 g. 10% Pd-C yielded 30% II, m. 246-8°. Catalytic reduction of 0.58 g. pyridoxal Et hemiacetal-HCl (IV) in 20 mL. EtOH and 0.5 g. 10% Pd-C (1 mol H absorbed) yielded 79% 6,5,3,4-Me(HO)(CH2OCH2)C5HN.HCl (V), m. 233-4°; picrate m. 186-7°. Similarly, 0.58 g. IV, 20 mL. H2O and 0.5 g. Pd-C yielded 40% II, m. 248-50°; 0.58 g. IV, 20 mL. HCl, 2.7 mL. 10% HCl and 0.5 g. Pd-C yielded 68% V, m. 225-30°. Catalytic reduction of 1.09 g. 2-HOCH2C5H4 N in 15 mL. MeOH and 51 mL. 5% HCl-MeOH with 1 g. Pd-C (260 mL. H absorbed in 2 h.) yielded 90% 2-MeC5H4N (VI); picrate m. 164-5°. Similarly, 1.23 g. 2-MeOCH2C5H4N in 15 mL. MeOH and 51 mL. 5% HCl-MeOH with 0.1 g. Pd-C (255 mL. H absorbed) yielded 91% 2-MeC5H4N; or, 2-AcOCH2C5H4N, in a similar way, yielded 88% 2-MeC5H4N. 2-HOCH2C5H4N.HCl (8 g.) added dropwise into 40 g. SOCl2 with cooling, refluxed 2 h., cooled, 100 mL. C6H6 added and the product filtered off gave 8.8 g. 2-ClCH2C5H4N (VII); picrate m. 146-7°. MeONa (2.72 g. Na and 55 mL. MeOH) treated dropwise with VII in 20 mL. MeOH, refluxed 1 h., the solvent removed and the residue extracted with Et2O gave 4.7 g. 2-MeOCH2C5H4N, b18 76-8°. Similarly are prepared (product, b.p./mm. and m.p. picrate given): 3-MeOCH2C5H4N, 92-4°/20, 117-18°; 4-MeOCH2C5H4N, 91-2°/19, 108-9°.
There is still a lot of research devoted to this compound(SMILES：OC1=C(C)C(CO)=CN=C1C.[H]Cl)Category: pyrimidines, and with the development of science, more effects of this compound(148-51-6) can be discovered.
Reference:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia