Misra Sudhindra N, Shukla Ram S, Gagnani Minaz A
Chemistry Department, Bhavnagar University, Bhavnagar 364 002, Gujarat, India.
J Colloid Interface Sci. 2005 Jan 1;281(1):164-70. doi: 10.1016/j.jcis.2004.08.077.
Bimetallic alkoxides of praseodymium and neodymium with aluminum, viz., MAl(OC(3)H(i)(7))(4), where M = Pr(III)/Nd(III), have been used as catalysts in Meerwein-Ponndorf-Verley (MPV) reduction of 2-octanone and benzophenone in isopropanol to give their corresponding secondary alcohols. The reduction of ketones is investigated by following the absorption spectra involving 4f-4f transitions. During the MPV reduction the oscillator strengths (P) and the Judd-Ofelt intensity (T(lambda), lambda = 2,4,6) parameters corresponding to each 4f-4f band (H43-->D21, H43-->P03, H43-->P13, and H43-->P23 in praseodymium, and I9/24-->F3/24, I9/24-->F5/24, I9/24-->F7/24, I9/24-->G5/24, and I9/24-->G7/24 in neodymium alkoxides) at different time intervals have also been calculated and used in the determination of rates. Rates were calculated in terms of complexation of ketone and isopropanol with MAl(OC(3)H(i)(7))(4) during the MPV reaction, from the changes in both absorbance and oscillator strength with time, and were found to be comparable, verifying the Judd-Ofelt theory. The stronger oxyphilicity of Pr(III) and Nd(III) in MAl(OC(3)H(i)(7))(4) than of their analogue Al(III) in Al(OC(3)H(i)(7))(3) made the bimetallic alkoxides better catalyst in MPV reduction of ketones.
镨和钕与铝的双金属醇盐，即MAl(OC(3)H(i)(7))(4)，其中M = Pr(III)/Nd(III)，已被用作催化剂，用于在异丙醇中将2-辛酮和二苯甲酮进行麦尔外因-彭多夫-韦利（MPV）还原反应，生成相应的仲醇。通过跟踪涉及4f-4f跃迁的吸收光谱来研究酮的还原反应。在MPV还原反应过程中，还计算了对应于每个4f-4f能带（镨中的H43-->D21、H43-->P03、H43-->P13和H43-->P23，以及钕醇盐中的I9/24-->F3/24、I9/24-->F5/24、I9/24-->F7/24、I9/24-->G5/24和I9/24-->G7/24）在不同时间间隔的振子强度（P）和贾德-奥费尔特强度（T(lambda)，lambda = 2,4,6）参数，并将其用于速率的测定。根据MPV反应过程中酮和异丙醇与MAl(OC(3)H(i)(7))(4)的络合情况，从吸光度和振子强度随时间的变化计算出反应速率，发现两者具有可比性，验证了贾德-奥费尔特理论。MAl(OC(3)H(i)(7))(4)中Pr(III)和Nd(III)比其类似物Al(OC(3)H(i)(7))(3)中的Al(III)具有更强的亲氧性，这使得双金属醇盐在酮的MPV还原反应中成为更好的催化剂。
