622-85-5Relevant articles and documents
Fragment ion formation in resonance enhanced multiphoton ionization (REMPI) of n-propyl phenyl ether in a supersonic jet
Song, Kyuseok,Van Eijk, Alexander,Shaler, Thomas A.,Morton, Thomas Hellman
, p. 4455 - 4460 (1994)
Resonance enhanced multiphoton ionization (REMPI) mass spectra of different conformational isomers of n-propyl phenyl ether at 30 K give the same fragmentation patterns. Laser REMPI excitation spectra exhibit three principal conformers in a supersonic free jet expansion. The most abundant species in the jet happens also to contribute the longest wavelength 0,0 band. SCF calculations suggest that the lowest energy structure corresponds to a gauche geometry in which all the carbons except that of the methyl group are essentially coplanar with the oxygen. This is confirmed by experimental observation of a predicted blue shift for a prominent vibrational overtone when the propyl group is partially deuterated (β,β-d2 or α,α,γ,γ,γ-ds). Time-of-flight mass spectra of deuterated analogues of each oF three conformers exhibits propene expulsion to yield PhOH?+ and PhOD?+ (the principal fragment ions) in which all seven alkyl hydrogens have become randomized within the chain. REMPI of individual conformer (via intermediacy of the lowest vibrational levels of their excited singlet electronic states) therefore gives the same outcome as does field ionization or electron impact source mass spectra. The predominant decomposition mechanism of the radical cation involves an ion-neutral complex, nPrOPh?+→[iPr+ PhO?], in which the hydrogens of the iPr+ undergo rapid internal transpositions prior to the ultimate decomposition step. Ab initio computations on a model system concur with the experimental inference that this mechanism operates regardless of the conformation of the precursor neutral.
Removal of Alkyl Sulfonates Using DABCO
Corazzata, Kaitlyn,Langston, Alexander,Lee, Elaine C.,Mo, Shunyan,Rose, Peter J.,Snodgrass, Joseph
supporting information, (2021/11/30)
During the route development of a midstage clinical candidate, we were challenged with a presence of alkyl sulfonates, which were identified as potential genotoxic impurities in our active pharmaceutical ingredient (API). As a result, we initiated a development effort to identify a method to remove the alkyl sulfonates that would be amenable for scale-up. Herein, we report our effort toward the development of a general approach using DABCO (1,4-diazabicyclo[2.2.2]octane) to remove alkyl sulfonates that is both efficient and convenient from the bench to scale-up.
Ambient Hydrogenation and Deuteration of Alkenes Using a Nanostructured Ni-Core–Shell Catalyst
Beller, Matthias,Feng, Lu,Gao, Jie,Jackstell, Ralf,Jagadeesh, Rajenahally V.,Liu, Yuefeng,Ma, Rui
supporting information, p. 18591 - 18598 (2021/06/28)
A general protocol for the selective hydrogenation and deuteration of a variety of alkenes is presented. Key to success for these reactions is the use of a specific nickel-graphitic shell-based core–shell-structured catalyst, which is conveniently prepared by impregnation and subsequent calcination of nickel nitrate on carbon at 450 °C under argon. Applying this nanostructured catalyst, both terminal and internal alkenes, which are of industrial and commercial importance, were selectively hydrogenated and deuterated at ambient conditions (room temperature, using 1 bar hydrogen or 1 bar deuterium), giving access to the corresponding alkanes and deuterium-labeled alkanes in good to excellent yields. The synthetic utility and practicability of this Ni-based hydrogenation protocol is demonstrated by gram-scale reactions as well as efficient catalyst recycling experiments.
