scholarly journals β-Enolization in α-phenyl-α,α′,α′-trimethylcycloalkanones

1992 ◽  
Vol 70 (5) ◽  
pp. 1274-1280 ◽  
Author(s):  
Wendy Sifton ◽  
J. B. Stothers ◽  
Shirley E. Thomas
Keyword(s):  
Secondary Alcohol ◽  
Ring Expansion ◽  
Methyl Groups ◽  
Proton Abstraction ◽  
Phenyl Proton ◽  
Methyl Derivatives ◽  
Cyclic Systems ◽  
A Minor ◽  
Acyclic Ketones ◽  
Derivatives Of

Ring expansion through β-proton abstraction from α-methyl groups has been observed for the α-phenyl-α,α′,α′,-tri-methyl derivatives of cyclopentanone and cyclohexanone upon treatment with t-BuO−/t-BuOH/185 °C. This contrasts with the lack of rearrangement found for the α,α,α′,α′-tetramethyl derivatives but is analogous to the behavior of some α-phenyl acyclic ketones. However, this process is reversible in the cyclic systems, but irreversible in the acyclic cases. For all of these α-phenyl substituted ketones, rearrangement is in competition with Haller–Bauer type cleavage. In the cyclic systems, a minor process was observed whereby some of the ring-expanded product is reduced to the corresponding secondary alcohol but there was no evidence of rearrangement through γ-enolate formation involving phenyl proton abstraction, which is a minor process in the α-phenyl acyclic systems.

13C magnetic resonance studies. 142. The fate of highly substituted acyclic ketones in strong base: β-enolization, Haller–Bauer cleavage, and an alkyl to aryl acyl shift

1990 ◽  
Vol 68 (7) ◽  
pp. 1106-1115 ◽  
Author(s):  
Rainer A. Dyllick-Brenzinger ◽  
Vijay Patel ◽  
Mollin B. Rampersad ◽  
J. B. Stothers ◽  
Shirley E. Thomas
Keyword(s):  
Magnetic Resonance ◽  
Proton Exchange ◽  
Methyl Groups ◽  
Strong Base ◽  
Proton Abstraction ◽  
Magnetic Resonance Studies ◽  
Significant Process ◽  
Cyclic Systems ◽  
Acyclic Ketones ◽  
Butyl Ketone

Di-tert-butyl ketone (2a), 5,5,7,7-tetramethyl-6-undecanone (2b), and 2,4-dimethyl-2,4-diphenyl-3-pentanone (2d) have been found to undergo slow rearrangement by β-proton abstraction from the α-methyl groups upon treatment with t-BuO−/t-BuOH/≥ 185 °C. This is in contrast to the absence of such rearrangement in cyclic systems. It is the only significant process observed for 2a and 2b, whereas with 2d and its monomethyl analog 22 Haller–Bauer type cleavage and an unprecedented 1,3-acyl shift from sp3 to sp2 carbon accompany the β-enolate rearrangement. The rates of 1H/2H exchange of the methyl protons in 2a, b were found to be similar to those reported for a variety of cyclic systems but this exchange does not occur in 2d, where only aryl proton exchange was observed. Keywords: β-enolization, acyclic ketones, acyl shift.

Carbon-13 nuclear magnetic resonance spectra in the identification of N-, O or S-methyl derivatives of some tautomeric hydroxy and mercapto nitrogen heterocycles

1984 ◽  
Vol 37 (11) ◽  
pp. 2391 ◽  
Author(s):  
GB Barlin ◽  
DJ Brown ◽  
MD Fenn
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nitrogen Heterocycles ◽  
Resonance Spectroscopy ◽  
Methyl Groups ◽  
Nuclear Magnetic Resonance Spectra ◽  
Methoxy Groups ◽  
Methyl Derivatives ◽  
Derivatives Of ◽  
Nuclear Magnetic

Carbon-13 nuclear magnetic resonance spectroscopy, in contrast to 1H n.m.r. spectroscopy, has been shown to provide a clear distinction in a variety of nitrogen heterocyclic systems between O-methyl and nuclear N-methyl groups. Methoxy groups were found to occur in the range δ�53.20-61.87, nuclear N-methyl groups at 34.29-49.62, and methylthio groups at 12.35-14.55 for the compounds examined in (D)chloroform. Data for N- and O-methyl derivatives of pyridin-2- and -4-ol,* the corresponding pyrimidines, and some sulfur analogues have been compared with those for the unmethylated parent compounds.

scholarly journals The synthesis and thermal decomposition of bis(phenylthio)methyl derivatives of mercury

1977 ◽  
Vol 55 (13) ◽  
pp. 2554-2558 ◽  
Author(s):  
Tristram Chivers ◽  
Ritchwick Ram
Keyword(s):  
Thermal Decomposition ◽  
Solid State ◽  
Minor Role ◽  
Homolytic Fission ◽  
Methyl Derivatives ◽  
A Minor ◽  
Derivatives Of

The mercurials, [(PhS)2CH]2Hg and PhHgCH(SPh)2, have been prepared from (PhS)2CHLi and HgBr2 or PhHgCl, respectively. The unsymmetrical compound decomposes readily both in the solid state and in various solvents. The symmetrical compound is more stable but also undergoes decomposition in certain refluxing solvents. The identity of the products suggests that the major decomposition route involves homolytic fission of the Hg—CH(SPh)2 bond and that PhS migration to mercury plays only a minor role.

Synthesis of Thieno[2,3-g][1,4]oxazonine and Thieno[2,3-h][1,5]oxazecine derivatives by cyanogen-bromide-induced ring expansion

1984 ◽  
Vol 37 (5) ◽  
pp. 1043 ◽  
Author(s):  
JB Bremner ◽  
EJ Browne ◽  
V Chohan ◽  
BF Yates
Keyword(s):  
Cyanogen Bromide ◽  
Ring Expansion ◽  
Standard Methods ◽  
Methyl Derivatives ◽  
Derivatives Of ◽  
Medium Ring

4-Phenyl-4,6,7,8,9,10-hexahydrothieno[2,3-g][1,4]oxazonine-8-carbonitrile (5a) and the analogous 4-phenyl-6,7,8,9,10,11-hexahydro-4H-thieno[2,3-h][1,5]oxazecine-9-carbonitrile (5b) were preparedin moderate yields by cyanogen bromide-induced ring expansion of the appropriate ω-(tetrahydrothieno[3,2-c]pyridyl)alkan-1-ol precursors (3). N-Methyl derivatives of these new fused medium-ring heterocyclic systems were prepared by standard methods.

Physical Properties of TCNQ Salts with N-Methyl Derivatives of Pyridine

1982 ◽  
Vol 85 (1) ◽  
pp. 257-263 ◽  
Author(s):  
A. Graja ◽  
M. Przybylski ◽  
B. Butka ◽  
R. Swietlik
Keyword(s):  
Physical Properties ◽  
Methyl Derivatives ◽  
Derivatives Of

Methyl derivatives of furan

1974 ◽  
Vol 39 (11) ◽  
pp. 3109-3116 ◽  
Author(s):  
J. Šrogl ◽  
M. Janda ◽  
I. Stibor ◽  
V. Skála ◽  
P. Trška ◽  
...  
Keyword(s):  
Methyl Derivatives ◽  
Derivatives Of

scholarly journals Avocado-Derived Biomass: Chemical Composition and Antioxidant Potential

Proceedings ◽  
2020 ◽  
Vol 70 (1) ◽  
pp. 100
Author(s):  
Minerva C. García-Vargas ◽  
María del Mar Contreras ◽  
Irene Gómez-Cruz ◽  
Juan Miguel Romero-García ◽  
Eulogio Castro
Keyword(s):  
Chemical Composition ◽  
Phenolic Content ◽  
Antioxidant Properties ◽  
Total Phenolic ◽  
Nutritional Properties ◽  
Aqueous Fraction ◽  
Extraction Solvent ◽  
Main Components ◽  
A Minor ◽  
Derivatives Of

Avocado has become fashionable due to its great organoleptic and nutritional properties. It is consumed as a fresh product and it is also processed to obtain salad oil and guacamole. In all cases, the only usable portion is the pulp. Therefore, to be a more sustainable and profitable agribusiness, it is important to recognize which compounds from the peel and the stone waste can be converted into valuable bio-products. Therefore, their chemical composition was determined according to the National Renewable Energy Laboratory, the total phenolic content by the Folin-Ciocalteu method and the antioxidant properties by the FRAP and TEAC assays. The main components of the peel and stone were acid-insoluble lignin (35.0% and 15.3%, respectively), polymeric sugars (23.6% and 43.9%, respectively), and the aqueous extractives (15.5% and 16.9%, respectively). Both biomasses contain lipids and protein, but a minor proportion (<6%). The valorization of lignin and sugars is of interest given the high content; stones are a rich source of glucose (93.2% of the polymeric fraction), which could be used to obtain biofuels or derivatives of interest. The extractive fraction of the peel contained the highest number of phenolic compounds (4.7 g/100 g biomass), mainly concentrated in the aqueous fraction (i.e., 87%) compared to the ethanol one, which was subsequently extracted. It correlated with major antioxidant activity and, therefore, the peel can be applied to obtain antioxidants and water can be used as an environmentally friendly extraction solvent.

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