Equilibrium studies of 5-substituted 4-hydroxy-2-methylpyrimidines. IV. Lactim-lactam tautomerism in methanol, n-butanol and n-hexane.

• 北川 隆康

• 水上 聰

• 平井 瑛三

抄録

Lactim-lactam tautomerism of 5-substituted 4-hydroxy-2-methylpyrimidines (R ; H, CH₃, OCH₃ and COOC₂H₅) was examined in MeOH, n-BuOH and n-hexane. All the compounds existed mainly in the lactam form (4(3H)-pyrimidone, IIb) in the alcohols. No substituent effect at 5-position on the tautomerism in the alcohols was observed. In n-hexane, 5-H and 5-CH₃ derivatives also existed mainly in the lactam form, IIb. 5-Carbethoxy-4-hydroxy-2-methylpyrimidine (4), however, existed mainly in the lactim form (4-pyrimidinol, I). The lactim form of 4 in n-hexane was changed into the lactam form, IIb, on addition of MeOH and n-BuOH to the solution. The conversion to the lactam form may be explained as a result of an association of two molecules of alcohol to 4, i. e., [chemical formula] The association was investigated quantitatively by ultraviolet spectrophotometry : K₁=1483±29 (MeOH-association) and K₁=1279±19 (n-BuOH-association). the tautomeric equilibrium constant (K_t ; K_t=[IIb]/[I]) in pure n-hexane was estimated to be less than 0.02.

収録刊行物

• ＣＨＥＭＩＣＡＬ　＆　ＰＨＡＲＭＡＣＥＵＴＩＣＡＬ　ＢＵＬＬＥＴＩＮ

  ＣＨＥＭＩＣＡＬ　＆　ＰＨＡＲＭＡＣＥＵＴＩＣＡＬ　ＢＵＬＬＥＴＩＮ 26 (5), 1403-1414, 1978

  公益社団法人 日本薬学会

キーワード

• association equilibria with alcohols

詳細情報

• CRID: 1390282679145257600
• NII論文ID: 110003623149
• NII書誌ID: AA00602100
• DOI: 10.1248/cpb.26.1403
• ISSN: 13475223
• ISSN: 00092363
• Web Site: http://www.jstage.jst.go.jp/article/cpb1958/26/5/26_5_1403/_pdf
• Web Site: https://search.jamas.or.jp/link/ui/1979070919
• 本文言語コード: en
• データソース種別:
  • JaLC
  • Crossref
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可