Photolysis of an asymmetrically substituted diazene in solution and in the crystalline state
Photolysis of an asymmetrically substituted diazene in solution and in the crystalline state
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DOI：
10.1039/b902272d
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发表时间：
2009-01-01
影响因子：
3.1
通讯作者：
Angel Garcia-Garibay, Miguel
中科院分区：
文献类型：
--
作者：
Ariel Hoijemberg, Pablo;Karlen, Steven D.;Angel Garcia-Garibay, Miguel
本文研究了二氮烯（1-联苯-4-基-1-甲基乙基）-叔丁基二氮烯和酮（2，4-双（联苯-4-基）-2，4-二甲基戊-3-酮）在固态和溶液中的稳态光解产物分布。这两种化合物在光解时产生1-联苯-4-基-1-甲基-乙基（BME中心点）自由基。酮产生两个单位的这个自由基，而二氮烯产生一个BME中心点和一个叔丁基自由基。在溶液中的两种化合物的产物分析使得有可能区分它们的来源，从其相应的双生笼，并从不同的遭遇对的情况下的不对称取代的二氮烯光解。在这种方式中，我们获得了一个完整的反应场景的二氮烯，一个有趣的功能作为自由基光引发剂的化合物，并作为在流体介质中的笼效应探针。在含有两个BME的笼中的反应。自由基显示出在从固相到液相时化合产物与纯化产物的比率降低4倍。相反，在含有BME的笼中反应。并且与晶体相比，叔丁基在液体中的结合与纯化比率显示出30倍的增加。我们分析了这些差异的原因，考虑在自由基的反应性和笼刚性的差异。
In this work we study the product distribution in the steady state photolysis of a diazene, (1-biphenyl-4-yl-1-methyl-ethyl)-tert-butyl diazene, and a ketone, 2,4-bis(biphenyl-4-yl)-2, 4-dimethyl-pentan-3-one, in the solid state and in solution. The two compounds yield 1-biphenyl-4-yl-1-methyl-ethyl (BME center dot) radicals upon photolysis. The ketone yields two units of this radical, whereas the diazene yields one BME center dot and one tert-butyl radical. Product analysis of the two compounds in solution makes it possible to differentiate their origin from their corresponding geminate cages, and from the different encounter pairs in the case of the asymmetrically substituted diazene photolysis. In this way we obtain a complete reaction scenery for the diazene, a compound with interesting features as a radical photoinitiator and as a cage effect probe in fluid media. The reaction in cages containing two BME. radicals shows a decrease by a factor of 4 in the ratio of combination to disproportionation products upon going from the solid to the liquid phase. On the contrary, the reaction in cages containing a BME. and a tert-butyl radical shows a 30-fold increase in combination to disproportionation ratio in liquid compared to the crystal. We analyze the reasons for these differences considering the differences in the reactivity of the radicals and in cage rigidity.