73120-52-2Relevant academic research and scientific papers
Reactions of diols with dimethyl carbonate in the presence of W(CO) 6 and Co2(CO)8
Khusnutdinov,Shchadneva,Mayakova
, p. 948 - 952 (2014/10/16)
Dimethoxyalkanes and dimethyl alkanediyl biscarbonates were synthesized by reactions of diols with dimethyl carbonate in the presence of tungsten and cobalt carbonyls. Optimal reactant and catalyst ratios and reaction conditions were found to ensure selective formation of dimethoxyalkanes or dimethyl alkanediyl biscarbonates.
Fingerprinting a Transition-Structure Guest by a Building-Block Approach with an Incremental Series of Catalytic Hosts. Structural Requirements for Glyme and α,ω-Dimethoxyalkane Catalyses in N-Methylbutylaminolysis and Butylaminolysis of 4-Nitrophenyl Acetate in Chlorobenzene
Hogan, John C.,Gandour, Richard D.
, p. 55 - 61 (2007/10/02)
Glymes, H-(CH2OCH2)n-H, GLM(n), catalyze butylaminolysis of 4-nitrophenyl acetate in chlorobenzene.Values of kcat/Oxy, where Oxy is the number of oxygens in the catalyst, increase with oligomer length up to triglyme, GLM(4), and then plateau.Optimal catalysis on a per oxygen basis requires a -(CH2OCH2)4-fragment, which suggests a four-point recognition of the secondary ammonium ion of the zwitterionic tetrahedral intermediate (TI) (J.Org.Chem. 1991, 56, 2821-2826).Dissection of individual structural components and reassembly to the same structure of the complexverifies this model.The following kinetic studies of 4-nitrophenyl acetate in chlorobenzene have accomplished the task: (a) methylbutylaminolysis catalyzed by GLM(n), n = 2-4; (b) methylbutylaminolysis catalyzed by α,ω-dimethoxyalkanes, CH3O-(CH2)n-OCH3, DME(n), n = 2-10 and 12; and (c) butylaminolysis catalyzed by DME(n), n = 2-10 and 12.Experiment a has revealed that kcat/Oxy is the same for GLM(2) - GLM(4).Optimal catalysis for breakdown of a zwitterionic TI with one ammonium proton only requires a -(CH2OCH2)2-fragment.Experiment b has shown that kcat/Oxy is largest for DME(2) with the values for the remaining DMEs 2 - 2.5-fold lower.A -CH2CH2- is the best spacer between the two oxygens.Thus, bifurcated hydrogen-bond formation between the two oxygens and the one ammonium proton enhances catalysis.Experiment c has revealed that kcat/Oxy for DME(2) exceeds the remaining DMEs by 3 - 3.6-fold, except for DME(8) and DME(10), which have values of kcat/Oxy only 1.7-fold slower.DME(8), the carba analogue of GLM(4), likely binds the two ammonium protons individually with the two oxygens.DME(10) behaves similarly.GLM(4) catalysis of butylaminolysis identifies -(CH2OCH2)4- as an optimal size.DME(8) catalysis confirms this size, although the two catalysts stabilize the two-proton ammonium ion differently.GLM(4) catalyzes butylaminolysis by forming two bifurcated hydrogen bonds.This suggested structure defines the size of the ammonium ion, which agrees with X-ray structural studies of polyether-ammonium complexes.Mechanistic proposals of butylaminolysis of aryl esters require such an ion.The results of this study confirm the stucture of the ion in the rate-limiting step.This building-block approach is a method for "fingerprinting" ammonium ions in transition structures of ionogenic reactions.
