159754-93-5

Upstream product

• 111-71-7 heptanal 
• 41251-37-0 methyl-d3-magnesium iodide 

Downstream Products

• 1449563-33-0 1-methyl-d₃-heptyl phenyl ether 

Relevant academic research and scientific papers

Reaction pathways and energetics of etheric C-O bond cleavage catalyzed by lanthanide triflates

Efficient and selective cleavage of etheric C-O bonds is crucial for converting biomass into platform chemicals and liquid transportation fuels. In this contribution, computational methods at the DFT B3LYP level of theory are employed to understand the efficacy of lanthanide triflate catalysts (Ln(OTf)3, Ln = La, Ce, Sm, Gd, Yb, and Lu) in cleaving etheric C-O bonds. In agreement with experiment, the calculations indicate that the reaction pathway for C-O cleavage occurs via a C-H → O-H proton transfer in concert with weakening of the C-O bond of the coordinated ether substrate to ultimately yield a coordinated alkenol. The activation energy for this process falls as the lanthanide ionic radius decreases, reflecting enhanced metal ion electrophilicity. Details of the reaction mechanism for Yb(OTf) 3-catalyzed ring opening are explored in depth, and for 1-methyl-d3-butyl phenyl ether, the computed primary kinetic isotope effect of 2.4 is in excellent agreement with experiment (2.7), confirming that etheric ring-opening pathway involves proton transfer from the methyl group alpha to the etheric oxygen atom, which is activated by the electrophilic lanthanide ion. Calculations of the catalytic pathway using eight different ether substrates indicate that the more rapid cleavage of acyclic versus cyclic ethers is largely due to entropic effects, with the former C-O bond scission processes increasing the degrees of freedom/particles as the transition state is approached.

β-deuterium kinetic isotope effects for identity processes: bromide ion substitution at 1-bromo-1-arylethanes and 2-bromooctane

While deuterian kinetic isotope effects for solvolyses have been extensively studied, other nucleophilic substitutions have received less attention, and identity processes, that is, substitutions where the nucleophile and leaving group are the same, have rarely been examined. Identity reactions must pass through a truly symmetrical stage, a transition state or an intermediate, so that data will be of interest to both theoretical and experimental chemists. Values of kH/kD have been determined by polarimetry for bromide exchange-racemization at ArCHBrCH3/CD3 (Ar = C6H5, 4-Br- and 4-Me-C6H4, and 3,4,-dimethyl-C6H3) in acetone, acetonitrile, and nitromethane. Observed values are analogous to values seen in solvolyses. They range from 1.01 to 1.35 and, in some cases, increase markedly as the concentration of Bu4NBr decreases. Solvolyses are either first order or pseudo first order whereas plotting observed racemization rate versus [Bu4NBr] allows separation of first- and second-order components; those species giving more stable carbocations in the more dipolar solvents, the systems showing kH/kD variation with Br- concentration, alone show an appreciable first-order component. The second-order kH/kD ratio averages 1.062 ±-0.018 at temperatures ranging from 25 to 50°C for all substrates in the three solvents, very analogous to the values seen for racemization of 1,1,1-d3-2-bromooctane or solvolysis of ethyl substrates but considerably lower than the typical solvolysis values of 1.15-1.25 for secondary, and 1.35-1.5 for tertiary substrates. The first-order kH/kD values obtained are higher, 1.1-1.5. These and other results are discussed.