Alkylation of solid sodium and lithium 2,6-dimethylphenoxide with methyl halide vapor

1969 ◽  
Vol 47 (19) ◽  
pp. 3637-3639 ◽  
Author(s):  
David Y. Curtin ◽  
Allan R. Stein
Keyword(s):  
Methyl Iodide ◽  
Heterogeneous Reactions ◽  
Methyl Halide

The generally accepted hypothesis that the alkylation of metal phenoxides is forced to occur at the ortho-carbon in heterogeneous reactions was investigated. Methyl iodide and bromide vapor reacts with crystalline sodium and lithium 2,6-dimethylphenoxides to give ortho-carbon/oxygen alkylation ratios not unlike those obtained in sealed tube reactions with an excess of methyl iodide or with added toluene as solvent. However, an unprecedented amount of para-methylation also occurred. The implications of these and related observations in other systems are discussed.

scholarly journals Femtosecond time-resolved photodissociation dynamics of methyl halide molecules on ultrathin gold films

2011 ◽  
Vol 2 ◽  
pp. 618-627 ◽  
Author(s):  
Mihai E Vaida ◽  
Robert Tchitnga ◽  
Thorsten M Bernhardt
Keyword(s):  
Methyl Iodide ◽  
Methyl Bromide ◽  
Uv Light ◽  
Strong Dependence ◽  
Methyl Chloride ◽  
Gold Surface ◽  
Rapid Quenching ◽  
Negative Ion ◽  
Time Resolved ◽  
Methyl Halide

The photodissociation of small organic molecules, namely methyl iodide, methyl bromide, and methyl chloride, adsorbed on a metal surface was investigated in real time by means of femtosecond-laser pump–probe mass spectrometry. A weakly interacting gold surface was employed as substrate because the intact adsorption of the methyl halide molecules was desired prior to photoexcitation. The gold surface was prepared as an ultrathin film on Mo(100). The molecular adsorption behavior was characterized by coverage dependent temperature programmed desorption spectroscopy. Submonolayer preparations were irradiated with UV light of 266 nm wavelength and the subsequently emerging methyl fragments were probed by photoionization and mass spectrometric detection. A strong dependence of the excitation mechanism and the light-induced dynamics on the type of molecule was observed. Possible photoexcitation mechanisms included direct photoexcitation to the dissociative A-band of the methyl halide molecules as well as the attachment of surface-emitted electrons with transient negative ion formation and subsequent molecular fragmentation. Both reaction pathways were energetically possible in the case of methyl iodide, yet, no methyl fragments were observed. As a likely explanation, the rapid quenching of the excited states prior to fragmentation is proposed. This quenching mechanism could be prevented by modification of the gold surface through pre-adsorption of iodine atoms. In contrast, the A-band of methyl bromide was not energetically directly accessible through 266 nm excitation. Nevertheless, the one-photon-induced dissociation was observed in the case of methyl bromide. This was interpreted as being due to a considerable energetic down-shift of the electronic A-band states of methyl bromide by about 1.5 eV through interaction with the gold substrate. Finally, for methyl chloride no photofragmentation could be detected at all.

scholarly journals The kinetics of certain reactions between methyl halides and anions in water

1949 ◽  
Vol 196 (1047) ◽  
pp. 540-553 ◽  
Keyword(s):  
Dipole Moment ◽  
Methyl Iodide ◽  
Methyl Bromide ◽  
Methyl Chloride ◽  
Polar Molecules ◽  
Methyl Halides ◽  
Methyl Halide ◽  
Kinetics Of ◽  
Chloride Methyl

The rates at which methyl chloride, methyl bromide and methyl iodide react with the hydroxyl and the thiosulphate ions in water have been measured at various concentrations and temperatures. The apparent energies of activation in both series increase in the same direction as the dipole moment of the methyl halide. The results are discussed in terms of a theory of the kinetics of the reactions between ions and polar molecules in solution.

Heterogeneous reactions of solid nickel(II) complexes, IV

1972 ◽  
Vol 4 (2) ◽  
pp. 153-160 ◽  
Author(s):  
E. Jóna ◽  
T. Šramko ◽  
P. Ambrovič ◽  
J. Gažo
Keyword(s):  
Heterogeneous Reactions ◽  
Solid Nickel

Femtosecond reaction dynamics of Rydberg states. Methyl iodide

1993 ◽  
Vol 214 (3-4) ◽  
pp. 281-289 ◽  
Author(s):  
M.H.M. Janssen ◽  
M. Dantus ◽  
H. Guo ◽  
A.H. Zewail
Keyword(s):  
Methyl Iodide ◽  
Rydberg States ◽  
Reaction Dynamics

scholarly journals Water-Soluble Ions in Atmospheric Aerosol Measured in a Semi-Arid and Chemical-Industrialized City, Northwest China

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 456
Author(s):  
Huimin Jiang ◽  
Zhongqin Li ◽  
Feiteng Wang ◽  
Xi Zhou ◽  
Fanglong Wang ◽  
...  
Keyword(s):  
Sulfur Oxidation ◽  
Northwest China ◽  
Water Soluble ◽  
Heterogeneous Reactions ◽  
Anthropogenic Source ◽  
Heating Period ◽  
Qinghai Province ◽  
Soluble Ions ◽  
Water Soluble Ions ◽  
Semi Arid

We investigated water-soluble ions (WSIs) of aerosol samples collected from 2016 to 2017 in Lanzhou, a typical semi-arid and chemical-industrialized city in Northwest China. WSIs concentration was higher in the heating period (35.68 ± 19.17 μg/m3) and lower in the non-heating period (12.45 ± 4.21 μg/m3). NO3−, SO42−, NH4+ and Ca2+ were dominant WSIs. The concentration of SO42− has decreased in recent years, while the NO3− level was increasing. WSIs concentration was affected by meteorological factors. The sulfur oxidation and nitrogen oxidation ratios (SOR and NOR) exceeded 0.1, inferring the vital contribution of secondary transformation. Meanwhile higher O3 concentration and temperature promoted the homogeneous reaction of SO2. Lower temperature and high relative humidity (RH) were more suitable for heterogeneous reactions of NO2. Three-phase cluster analysis illustrated that the anthropogenic source ions and natural source ions were dominant WSIs during the heating and non-heating periods, respectively. The backward trajectory analysis and the potential source contribution function model indicated that Lanzhou was strongly influenced by the Hexi Corridor, northeastern Qinghai–Tibetan Plateau, northern Qinghai province, Inner Mongolia Plateau and its surrounding cities. This research will improve our understanding of the air quality and pollutant sources in the industrial environment.

scholarly journals Improved synthesis of SV2A targeting radiotracer [11C]UCB-J

2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Johanna Rokka ◽  
Eva Schlein ◽  
Jonas Eriksson
Keyword(s):  
Methyl Iodide ◽  
Water Solution ◽  
Synthesis Method ◽  
Radiochemical Yield ◽  
Preparative Hplc ◽  
Step Method ◽  
Synaptic Density ◽  
Excellent Starting Point ◽  
Starting Point

Abstract Introduction [11C]UCB-J is a tracer developed for PET (positron emission tomography) that has high affinity towards synaptic vesicle glycoprotein 2A (SV2A), a protein believed to participate in the regulation of neurotransmitter release in neurons and endocrine cells. The localisation of SV2A in the synaptic terminals makes it a viable target for in vivo imaging of synaptic density in the brain. Several SV2A targeting compounds have been evaluated as PET tracers, including [11C]UCB-J, with the aim to facilitate studies of synaptic density in neurological diseases. The original two-step synthesis method failed in our hands to produce sufficient amounts of [11C]UCB-J, but served as an excellent starting point for further optimizations towards a high yielding and simplified one-step method. [11C]Methyl iodide was trapped in a clear THF-water solution containing the trifluoroborate substituted precursor, potassium carbonate and palladium complex. The resulting reaction mixture was heated at 70 °C for 4 min to produce [11C]UCB-J. Results After semi-preparative HPLC purification and reformulation in 10% ethanol/phosphate buffered saline, the product was obtained in 39 ± 5% radiochemical yield based on [11C]methyl iodide, corresponding to 1.8 ± 0.5 GBq at EOS. The radiochemical purity was > 99% and the molar activity was 390 ± 180 GBq/μmol at EOS. The product solution contained < 2 ppb palladium. Conclusions A robust and high yielding production method has been developed for [11C]UCB-J, suitable for both preclinical and clinical PET applications.

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