Behavior of Ketyl radical in the micelle solution in the presence of silver ion or silver particle

银离子或银颗粒存在下胶束溶液中的酮基行为

• 批准号: 08650977
• 负责人: SATO Tomoo
• 金额: $ 1.47万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650977/
• 关键词: Silver colloid; Benzophenone; Acetophenone; Sensitized photoreduction; Micelle; Ketyl radical; Photo-acetone method; Photolysis; 増感光還元反応; 表面プラズモン

"Photo-acetone method" has been known as a tractable method to prepare finely dispersed colloidal metals (Ag, Au, Pt and Cu). In this study, aromatic ketone was used instead of acetone in order to investigate the role of the ketyl radical during the reaction. Aqueous silver percholate solutions were photolyzed with near-UV light in the presence of sodium dodecylsulfate (SDS) micelle and aromatic ketone, such as benzophenone and acetophenone. The formation of finely dispersed colloidal silver and the photobleach of aromatic ketone were caused by irradiation with near-UV light, which was absorbed solely by aromatic ketone (sensitized photoreduction). Gross features of the sensitized photoreduction of silver ion and the photobleach of aromatic ketone were interpreted in term of a simple reaction scheme entailing suitable combinations of the kinetics parameters. Namely, the excitation of aromatic ketone by near-UV light yields an aromatic ketone triplet, which abstracts an H atom from SDS micelle, giving rise to a ketyl radical. Some ketyl radical reduces silver ion and silver ion cluster and goes back to aromatic ketone. Other ketyl radical changes into certain byproducts such as the corresponding pinacol, hydrol and coupling compound with SDS.It was noticed that an extinction coefficient of colloidal silver formed during the early stage was smaller than the usual value because of the size effect of the particles. The existence of the ketyl radical of benzophenone in the reaction mixture was confirmed by laser photolvsis, It was tried to compare the lifetime of the ketyl radical under various reaction conditions. Taking advantage of the unique reaction process of the photo-acetone method, the composite noble metal colloid, whose structure and spectroscopic properties were different from alloy colloid, has been successfully prepared.

“照片 - 丙酮法”被称为制备精细分散的胶体金属（AG，AU，PT和CU）的可拖动方法。在这项研究中，使用芳香族酮代替丙酮，以研究反应过程中酮基自由基的作用。在存在十二烷基硫酸钠（SDS）胶束和芳香族酮的存在下，将圆锥形溶液的水溶液溶液（例如苯二酮和乙醇酮）在存在下。分散的胶体银的形成和芳香酮的光漂白是由近紫外光照射引起的，近紫外光仅被芳香族酮（敏化光元素）吸收。用简单的反应方案来解释银离子和芳香酮的光漂白的敏化光元素的总特征，该方案需要适当的动力学参数组合。也就是说，近紫外光对芳族酮的激发产生了一个芳香的酮三重态，该三酮三重态从SDS胶束中抽象H原子，从而产生了酮基自由基。一些酮自由基减少了银离子和银离子簇，并返回芳香族酮。其他酮自由基变为某些副产品，例如与SDS的相应的Pinacol，Hydrol和耦合化合物。注意到在早期阶段形成的胶体银的灭绝系数由于颗粒的尺寸效应而小于通常的值。通过激光Photolvsis证实了苯甲酮在反应混合物中的酮自由基的存在，试图比较各种反应条件下的酮基自由基的寿命。利用光丙酮法的独特反应过程，复合贵金属胶体的结构和光谱特性与合金胶体不同。