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N~1,N~3-二氧化-4-羟基喹唑啉(Ⅰ)与浓盐酸回馏作用,得75—81％的2,4,6一三羟基喹唑啉(Ⅱ),11—17％的N~3-氧化-4-羥基-6-氯喹唑啉(Ⅳ,N~3-羥基-6-氯喹唑酮-4)及2—3％的3,5-二氯邻氨基苯甲酸(Ⅴ)。化合物Ⅱ的结构是借与已知样品的混合熔点及其6-乙酰基衍生物而加以确证。化合物Ⅳ的结构是借(1)其氧化降解为2-硝基-5-氯苯甲酸;(2)其碱性水解为5-氯邻氨基苯甲酸;(3)经铁粉-盐酸还原为4-羥基-6-氯喹唑啉,及(4)其红外吸收光谱显示N—O吸收峯等事实推定。根据红外吸收光谱及化学性质我们认为化合物Ⅳ是以两种互变异构体形式存在。由于它显示有喹唑啉环的特征吸收峯(1515,1563及1613厘米~(-1)),但在1695厘米~(-1)处无羰基的吸收峯,及在氯化铁催化剂存在下可以为铁粉还原而得脱氧衍生物,这就指示N~3-氧化物(Ⅳa)的结构存在。另一方面,化合物Ⅳ溶于碳酸氢钠溶液,在乙酸铜的微酸性乙醇液中形成不溶性的铜盐沉淀,及其对于浓盐酸的不活泼性,则均支持N~3-羥肟酸(Ⅳb)的结构。化合物Ⅴ的结构是借与已知物的混合熔点,与乙酸酐形成2-甲基-6,8-二氯苯骈噁嗪-3,1-酮-4,及后者变为N-乙酰基-3,5-二氯邻氨基苯甲酸等事实而确证。化合物Ⅳ虽不能在热浓盐酸中产生重排反应,但与五氯化磷-三氯氧化磷反应后,产物经浓盐酸水解,则得重排产物2,4-二羟基-6-氯喹唑啉。
N ~ 1, N ~ 3-dioxido-4-hydroxyquinazoline (Ⅰ) and concentrated hydrochloric acid back to give 75-81% of 2,4,6-trihydroxyquinazoline (Ⅱ), 11- 17% of N ~ 3-oxo-4-hydroxy-6-chloroquinazoline (IV, N ~ 3-hydroxy-6-chloroquinazolone- 4) and 2-3% Formic acid (V). The structure of compound II was confirmed by mixing with known samples and its 6-acetyl derivative. The structure of compound IV is (1) its oxidative degradation is 2-nitro-5-chlorobenzoic acid; (2) its basic hydrolysis is 5-chloroanthranilic acid; (3) 4-hydroxy-6-chloroquinazoline, and (4) the fact that its infrared absorption spectrum shows an N-O absorption peak and the like. According to the infrared absorption spectra and chemical properties, we believe that the compound Ⅳ exists as two tautomers. Since it shows the characteristic absorption peaks of the quinazoline ring (1515, 1563 and 1613 cm -1), there is no carbonyl absorption peak at 1695 cm -1, and there is no carbonyl absorption peak in the presence of a ferric chloride catalyst Deoxidation of iron powder can be deoxidized derivatives, which indicates that the structure of N ~ 3-oxide (IVa) exists. On the other hand, compound IV was dissolved in sodium bicarbonate solution to form insoluble copper salt precipitate in the slightly acidic ethanolic copper acetate solution and its inactivity with concentrated hydrochloric acid supported N ~ 3-hydroxamic acid ( IVb) structure. The structure of compound V is obtained by mixing 2-methyl-6,8-dichlorobenzoxazin-3,1-one-4 with acetic anhydride and mixing the latter with N-acetyl 3,5-dichloro-anthranilic acid and so on. Although the compound IV can not produce rearrangement reaction in hot concentrated hydrochloric acid, after the reaction with phosphorus pentachloride-phosphorus oxychloride, the product is hydrolyzed by concentrated hydrochloric acid to obtain rearranged products of 2,4-dihydroxy-6-chloroquinazole Morpholine.