591-40-2Relevant academic research and scientific papers
Carbomethoxylating reactivity of methyl phenyl carbonate toward aromatic amines in the presence of group 3 metal (Sc, La) triflate catalysts
Distaso, Monica,Quaranta, Eugenio
, p. 36 - 42 (2004)
Methyl phenyl carbonate (MPC) has been investigated as a carbomethoxylating agent of aromatic amines in the presence of group 3 metal (Sc or La) triflate catalysts. Under mild conditions (363 K), both Sc(OTf)3 and La(OTf)3 (OTf=O3SCF3) can promote the carbamation of aniline and a few industrially relevant aromatic diamines, such as 4,4′-methylenedianiline (MDA) and 2,4-diaminotoluene (TDA), with MPC. Carbamate yield and selectivity are markedly affected by the experimental conditions (temperature, reaction medium, nature of the metal center). Sc(OTf)3 is a more effective and selective carbamation catalyst than La(OTf)3 . Ad hoc experiments have shown that, in the presence of the M(OTf)3 (M=Sc, La) catalysts, MPC is not only more reactive but also a more selective carbomethoxylating agent than dimethyl carbonate (DMC).
Fe-Mediated Nitrogen Fixation with a Metallocene Mediator: Exploring p Ka Effects and Demonstrating Electrocatalysis
Chalkley, Matthew J.,Del Castillo, Trevor J.,Matson, Benjamin D.,Peters, Jonas C.
supporting information, p. 6122 - 6129 (2018/05/14)
Substrate selectivity in reductive multielectron/proton catalysis with small molecules such as N2, CO2, and O2 is a major challenge for catalyst design, especially where the competing hydrogen evolution reaction (HER) is thermodynamically and kinetically competent. In this study, we investigate how the selectivity of a tris(phosphine)borane iron(I) catalyst, P3BFe+, for catalyzing the nitrogen reduction reaction (N2RR, N2-to-NH3 conversion) versus HER changes as a function of acid pKa. We find that there is a strong correlation between pKa and N2RR efficiency. Stoichiometric studies indicate that the anilinium triflate acids employed are only compatible with the formation of early stage intermediates of N2 reduction (e.g., Fe(NNH) or Fe(NNH2)) in the presence of the metallocene reductant Cp?2Co. This suggests that the interaction of acid and reductant is playing a critical role in N-H bond-forming reactions. DFT studies identify a protonated metallocene species as a strong PCET donor and suggest that it should be capable of forming the early stage N-H bonds critical for N2RR. Furthermore, DFT studies also suggest that the observed pKa effect on N2RR efficiency is attributable to the rate and thermodynamics of Cp?2Co protonation by the different anilinium acids. Inclusion of Cp?2Co+ as a cocatalyst in controlled potential electrolysis experiments leads to improved yields of NH3. The data presented provide what is to our knowledge the first unambiguous demonstration of electrocatalytic nitrogen fixation by a molecular catalyst (up to 6.7 equiv of NH3 per Fe at -2.1 V vs Fc+/0).
Amino Acids, 4 - Enantioselective Synthesis of N-Substituted α-Amino Carboxylic Acids from α-Hydroxy Carboxylic Acids
Effenberger, Franz,Burkard, Ulrike,Willfahrt, Joachim
, p. 314 - 333 (2007/10/02)
With primary and secondary amines, the (S)-α-(trifluoromethylsulfonyloxy) carboxylates (S)-3 afford in an SN2 reaction the N-substituted (R)-α-amino carboxylates (R)-5, (R)-9, and (R)-12, resp.The rates of α-substituted ethyl propionates decrease in the order of the substituents triflate (3a) >> bromide (8a) > mesylate (7a) >= tosylate (7b) > chloride (8b); in the reactions with amines, decreasing reactivity affords increasing racemisation and elimination as a consequence of the more drastic conditions which are required
