Metastable McLafferty rearrangement reaction in the electron impact ionization of stearic acid methyl ester

1995 ◽  
Vol 144 (3) ◽  
pp. 199-204 ◽  
Author(s):  
Mitsuo Takayama
Keyword(s):  
Methyl Ester ◽  
Stearic Acid ◽  
Electron Impact ◽  
Impact Ionization ◽  
Acid Methyl Ester ◽  
Electron Impact Ionization ◽  
Mclafferty Rearrangement ◽  
Acid Methyl ◽  
Rearrangement Reaction ◽  
Stearic Acid Methyl Ester

Electron-Impact Ionization of Mandelic Acid and Mandelic Acid Methyl Ester as Prototypes for the C6H5CH(OH)-X System: Ionization and Appearance Energies, Activation Energies and Enthalpies of Formation

2005 ◽  
Vol 11 (4) ◽  
pp. 371-380 ◽  
Author(s):  
Joachim Opitz
Keyword(s):  
Methyl Ester ◽  
Electron Impact ◽  
Mandelic Acid ◽  
Impact Ionization ◽  
Acid Methyl Ester ◽  
Electron Impact Ionization ◽  
Molecular Ions ◽  
Enthalpies Of Formation ◽  
Ionization Mass ◽  
Acid Methyl

Electron-impact ionization mass spectra, the decay of metastable ions, ionization and appearance energies and bond energies, as dissociation energies, are reported for mandelic acid (MA) and mandelic acid methyl ester (MAME) . An ionization energy of 8.55 eV was obtained for both compounds. For the formation of C6H5+ ions, appearance energies of 14.25 eV or 14.40 eV were determined for MA or MAME, respectively. On the main fragmentation route from molecular ions to these C6H5+ ions, an activation energy of (1.1±0.1)eV in excess of the calculated total reaction enthalpy was found for the elimination of CO from the prominent C7H7O+ ions to C6H7+ ions, involving the transfer of two H-atoms. The second (minor) fragmentation route via C7H6O+ions resembles the benzaldehyde decomposition pathway and the individual steps were found to be near to their calculated thermochemical reaction enthalpies. Gas-phase enthalpies of formation of (–4.652±0.3 eV) [≡ (–448.8±30) kJ mol−1] for MA and (–4.243±0.3) eV [≡ (–409.4±30) kJ mol−1] for MAME are derived, based on the appearance energy of their C7H7O+ ions at m/z 107 and the formation enthalpy adopted from protonated benzaldehyde. The results are compared with data for benzylalcohol.

scholarly journals Cu2+ Montmorillonite K10 Clay Catalyst as a Green Catalyst for Production of Stearic Acid Methyl Ester: Optimization Using Response Surface Methodology (RSM)

2018 ◽  
Vol 13 (1) ◽  
pp. 187 ◽  
Author(s):  
Enas A. Almadani ◽  
Farah W. Harun ◽  
Salina M. Radzi ◽  
Syamsul K. Muhamad
Keyword(s):  
Reaction Time ◽  
Methyl Ester ◽  
Stearic Acid ◽  
Response Surface ◽  
Reaction Temperature ◽  
Acid Methyl Ester ◽  
Montmorillonite K10 ◽  
Acid Methyl ◽  
Stearic Acid Methyl Ester ◽  
Clay Catalyst

Clay catalyst has received much attention to replace the homogeneous catalysts in the esterification reaction to produce fatty acid methyl ester as the source of biodiesel as it is low cost, easily available, as well as environmental friendly. However, the use of unmodified clay, in particular montmorillonite K10 (MMT K10), for the esterification of fatty acids showed that the acid conversion was less than 60% and this is not preferable to the production of biodiesel. In this study, synthesis of stearic acid methyl ester using Cu2+-MMT K10 (Cu-MMT K10) was successfully optimized via response surface methodo-logy (RSM) based on 3-variable of Box-Behnken design (BB). The parameters were; reaction time (5-180 minutes), reaction temperature (80-120 oC) and concentration of Cu2+ in MMT K10 (0.25-1 M). The use of RSM in optimizing the conversion of stearic acid was successfully developed as the actual experimental conversion of stearic acid was found similar to the actual values under the optimum conditions. The model equation predicted that the following conditions would generate the maximum conversion of stearic acid (87.05 %reaction time of 62 minutes, a reaction temperature of 80 oC and catalyst used is 1.0 M Cu-MMT K10. This finding can be considered as green catalytic process as it worked at moderate reaction temperature using low cost clay catalyst with a short reaction time. Copyright © 2018 BCREC Group. All rights reservedReceived: 26th July 2017; Revised: 13rd January 2018; Accepted: 13rd January 2018; Available online: 22nd January 2018; Published regularly: 2nd April 2018How to Cite: Almadani, E.A., Harun, F.W., Radzi, S.M., Muhamad, S.K. (2018). Cu2+ Montmorillonite K10 Clay Catalyst as a Green Catalyst for Production of Stearic Acid Methyl Ester: Optimization Using Response Surface Methodology (RSM). Bulletin of Chemical Reaction Engineering & Catalysis, 13 (1): 187-195 (doi:10.9767/bcrec.13.1.1397.187-195) 

Stearic acid methyl ester affords neuroprotection and improves functional outcomes after cardiac arrest

2020 ◽  
Vol 159 ◽  
pp. 102138 ◽  
Author(s):  
Po-Yi Chen ◽  
Celeste Yin-Chieh Wu ◽  
Garrett A. Clemons ◽  
Cristiane T. Citadin ◽  
Alexandre Couto e Silva ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Methyl Ester ◽  
Stearic Acid ◽  
Functional Outcomes ◽  
Acid Methyl Ester ◽  
Acid Methyl ◽  
Stearic Acid Methyl Ester

scholarly journals Notizen: Zur elektronenstoßinduzierten Isomerisierung und Fragmentierung von Butencarbonsäuremethylestern.

1976 ◽  
Vol 31 (7) ◽  
pp. 1013-1014 ◽  
Author(s):  
Rupert Herrmann ◽  
Helmut Schwarz
Keyword(s):  
Methyl Ester ◽  
Carbon Atom ◽  
Electron Impact ◽  
Acid Methyl Ester ◽  
Photochemical Behavior ◽  
Acid Methyl ◽  
Butenoic Acid

On the contrary to the photochemical behavior the title compounds do not isomerise to a common intermediate prior to or during electron impact induced fragmentation. The unusual methyl elimination from the trans(2)-butenoic acid methyl ester probably is accompanied by a concerted [1.3] methoxy rearrangement from the ester function on to the β carbon atom.

Mechanismen der elektronenstoßinduzierten Methanoleliminierung aus ortho- und para-substituierten Benzoesäuremethylestern / Mechanisms of Electron Impact Induced Elimination of Methanol from ortho- and para-Substituted Benzoic Acid Methyl Ester

1976 ◽  
Vol 31 (6) ◽  
pp. 870-875 ◽  
Author(s):  
Rupert Herrmann ◽  
Helmut Schwarz
Keyword(s):  
Mass Spectrometry ◽  
Methyl Ester ◽  
Benzoic Acid ◽  
Electron Impact ◽  
Acid Methyl Ester ◽  
Ring Expansion ◽  
Acid Methyl ◽  
Π Complex ◽  
Fragmentation Reactions ◽  
Ring Expansion Reaction

Using deuterium labelled compounds the mechanisms of methyl as well as methanol elimination from the title compounds have been established. It can be shown that in the case of 4-methoxy-methyl benzoic acid methyl ester the unusual methanol elimination from the [M-methyl]+ ion probably proceeds via the formation of a π-complex and a ring expansion reaction. In addition to this novel fragmentation some ortho-effects and other fragmentation reactions useful for an analytical identification of the ortho/para-isomers by means of mass spectrometry are discussed.

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