Basicity of nitrogen–sulphur(VI) compounds. Part 6. Ionization of NN′-di-and N-mono-substituted sulphamides and dihydro-2,1,3-benzothiadiazoline and benzothiadiazine 2,2-dioxides (cyclic sulphamides)
Basicity of nitrogen–sulphur(VI) compounds. Part 6. Ionization of NN′-di-and N-mono-substituted sulphamides and dihydro-2,1,3-benzothiadiazoline and benzothiadiazine 2,2-dioxides (cyclic sulphamides)
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氮-硫 (VI) 化合物的碱度。第 6 部分。NN-二-和 N-单取代磺酰胺和二氢-2,1,3-苯并噻二唑啉和苯并噻二嗪 2,2-二氧化物（环状磺酰胺）的电离
DOI：
10.1039/p29840001851
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
W. Spillane
中科院分区：
文献类型：
--
作者：
P. Burke;S. McDermott;T. Hannigan;W. Spillane
36 已合成了二取代、单取代和两个三取代的磺酰胺，并研究了它们在碱中的电离平衡（方案 1-3）。许多磺酰胺都是新材料。每个系列获得的 pKa 值已在哈米特和塔夫脱图中相关。附近氢的电离获得的 Hammett ρ 值约为2.3. “远程”氢电离获得的 Taft ρ* 值为 1.68。六元环状磺酰胺的酸性比其无环类似物高约 10%。 2.5 pKa 单位和五元环磺酰胺约为 2.5 pKa 单位。比开链模型的酸性更强 4 个 pKa 单位。硫 d 轨道参与和环应变被认为是这种“酸强化”效应的可能来源。
36 Di- and mono- and two tri-substituted sulphamides have been synthesised and their ionization equilibria in base (Schemes 1–3) have been studied. Many of the sulphamides are new materials. The pKa values obtained for each series have been correlated in Hammett and Taft plots. The Hammett ρ values obtained for the ionization of the proximate hydrogen are ca. 2.3. The Taft ρ* value obtained for ionization of the ‘remoter’ hydrogen is 1.68. The six-membered cyclic sulphamides are more acidic than their acyclic analogues by ca. 2.5 pKa units and the five-membered cyclic sulphamides are ca. 4 pKa units more acidic than model open-chain counterparts. Sulphur d-orbital involvement and ring-strain are suggested as possible sources of this ‘acid-strengthening’ effect.