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.

A Hydrogen Bonded Aluminium Alkoxide Hydroxide Aggregate Resulting from the Exposure of Methylaluminium Dichloride to Air

2003 ◽  
Vol 58 (5) ◽  
pp. 489-492 ◽  
Author(s):  
Norbert W. Mitzel ◽  
Christian Lustig
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Oxidation Product ◽  
Minor Role ◽  
Primary Reaction ◽  
A Minor ◽  
Aluminium Alkoxide ◽  
Hydrogen Bonded

Exposure of methylaluminium dichloride to air results in the formation of a crystalline hydrolysis/ oxidation product of the composition [(MeOAlCl2)3][(MeOAlCl2)2(HOAlCl2)], which is linked by a H···Cl hydrogen bond in the solid state. Oxygen is thus inserted into the carbon-aluminium bond in the primary reaction, whereas hydrolysis plays only a minor role.

scholarly journals σB Modulates Virulence Determinant Expression and Stress Resistance: Characterization of a Functional rsbU Strain Derived from Staphylococcus aureus 8325-4

2002 ◽  
Vol 184 (19) ◽  
pp. 5457-5467 ◽  
Author(s):  
Malcolm J. Horsburgh ◽  
Joanne L. Aish ◽  
Ian J. White ◽  
Les Shaw ◽  
James K. Lithgow ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Minor Role ◽  
Gene Encoding ◽  
Phenotypic Properties ◽  
Relative Level ◽  
General Stress Response ◽  
A Minor ◽  
Derivatives Of

ABSTRACT The accessory sigma factor σB controls a general stress response that is thought to be important for Staphylococcus aureus survival and may contribute to virulence. The strain of choice for genetic studies, 8325-4, carries a small deletion in rsbU, which encodes a positive regulator of σB activity. Consequently, to enable the role of σB in virulence to be addressed, we constructed an rsbU + derivative, SH1000, using a method that does not leave behind an antibiotic resistance marker. The phenotypic properties of SH1000 (8325-4 rsbU +) were characterized and compared to those of 8325-4, the rsbU mutant, parent strain. A recognition site for σB was located in the promoter region of katA, the gene encoding the sole catalase of S. aureus, by primer extension analysis. However, catalase expression and activity were similar in SH1000 (8325-4 rsbU +), suggesting that this promoter may have a minor role in catalase expression under normal conditions. Restoration of σB activity in SH1000 (8325-4 rsbU +) resulted in a marked decrease in the levels of the exoproteins SspA and Hla, and this is likely to be mediated by reduced expression of agr in this strain. By using Western blotting and a sarA-lacZ reporter assay, the levels of SarA were found to be similar in strains 8325-4 and SH1000 (8325-4 rsbU +) and sigB mutant derivatives of these strains. This finding contrasts with previous reports that suggested that SarA expression levels are altered when they are measured transcriptionally. Inactivation of sarA in each of these strains resulted in an expected decrease in agr expression; however, the relative level of agr in SH1000 (8325-4 rsbU +) remained less than the relative levels in 8325-4 and the sigB mutant derivatives. We suggest that SarA is not likely to be the effector in the overall σB-mediated effect on agr expression.

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.

scholarly journals The fumarate salts of the N-isopropyl-N-methyl derivatives of DMT and psilocin

2019 ◽  
Vol 75 (9) ◽  
pp. 1316-1320 ◽  
Author(s):  
Andrew R. Chadeayne ◽  
Duyen N. K. Pham ◽  
James A. Golen ◽  
David R. Manke
Keyword(s):  
Solid State ◽  
Hydrogen Bonds ◽  
Water Molecule ◽  
Side Chain ◽  
Two Dimensional ◽  
Asymmetric Unit ◽  
Ethyl Methyl ◽  
Methyl Derivatives ◽  
Solid State Structures ◽  
Derivatives Of

The solid-state structures of the salts of two substituted tryptamines, namely N-isopropyl-N-methyltryptaminium (MiPT) fumarate {systematic name: [2-(1H-indol-3-yl)ethyl](methyl)propan-2-ylazanium 3-carboxyprop-2-enoate}, C14H21N2 +·C4H3O4 −, and 4-hydroxy-N-isopropyl-N-methyltryptaminium (4-HO-MiPT) fumarate monohydrate {systematic name: [2-(4-hydroxy-1H-indol-3-yl)ethyl](methyl)propan-2-ylazanium 3-carboxyprop-2-enoate monohydrate}, C14H21N2O+·C4H3O4 −·H2O, are reported. Both salts possess a protonated tryptammonium cation and a 3-carboxyacrylate (hydrogen fumarate) anion in the asymmetric unit; the 4-HO-MiPT structure also contains a water molecule of crystallization. Both cations feature disorder of the side chain over two orientations, in a 0.630 (3):0.370 (3) ratio for MiPT and a 0.775 (5):0.225 (5) ratio for 4-HO-MiPT. In both extended structures, N—H...O and O—H...O hydrogen bonds generate infinite two-dimensional networks.

Evidence for lack of a role of cGMP in effect of alpha-hANP on aldosterone inhibition

1987 ◽  
Vol 252 (5) ◽  
pp. E643-E647 ◽  
Author(s):  
H. Matsuoka ◽  
M. Ishii ◽  
Y. Hirata ◽  
K. Atarashi ◽  
T. Sugimoto ◽  
...  
Keyword(s):  
Inhibitory Effect ◽  
Minor Role ◽  
Dependent Manner ◽  
Free Medium ◽  
Adrenal Cells ◽  
Aldosterone Production ◽  
A Minor ◽  
Dose Dependent ◽  
Derivatives Of

To investigate the role of guanosine 3',5'-cyclic monophosphate (cGMP) in the inhibitory effect on aldosterone production of alpha-human atrial natriuretic polypeptide (alpha-hANP) we first compared the effects of the peptide with those of sodium nitroprusside (SNP) on the production of aldosterone and cGMP in dispersed adrenal capsular cells of rats, second, examined the effects of derivatives of cGMP on the production of aldosterone, and, third, studied the influence of potassium on the effects of alpha-hANP on the production of aldosterone and cGMP. alpha-hANP at concentrations of 3 X 10(-8) to 3 X 10(-7) M decreased the production of aldosterone in a dose-dependent manner, while markedly increasing the production of cGMP. On the other hand, although SNP at concentrations of 10(-5) to 10(-3) M increased the production of cGMP in a dose-dependent manner, it caused no significant changes in the production of aldosterone. Neither dibutyryl cGMP nor 8-bromo-cGMP affected the production of aldosterone in the adrenal cells. Although the aldosterone-inhibitory effect of alpha-hANP was lost in the potassium-free medium, the cGMP-stimulatory effect of the peptide was not altered by adding potassium to the incubation medium at concentrations of 0-5 meq/l. These results suggest that cGMP plays a minor role in the inhibitory effect of alpha-hANP on the production of aldosterone and that the production of cGMP stimulated by the peptide is not directly involved in the decrease in aldosterone production in adrenal capsular cells of rats.

Clay crystal-chemical adaptability and transformation mechanisms

Clay Minerals ◽  
2012 ◽  
Vol 47 (2) ◽  
pp. 147-164 ◽  
Author(s):  
J. Cuadros
Keyword(s):  
Solid State ◽  
Reaction Mechanisms ◽  
Morphological Changes ◽  
Atomic Scale ◽  
Small Scale ◽  
Minor Role ◽  
Crystal Chemical ◽  
State Transformation ◽  
Solid State Transformation ◽  
A Minor

AbstractChemical and mineralogical transformations of phyllosilicates are among the most important in diagenetic environments in all types of rocks because they can exert a large control on the processes taking place in such environments and/or provide constraints for the conditions in which phyllosilicate transformation occurred. Dissolution-precipitation and solid-state transformation are usually the two mechanisms proposed for such reactions depending on the crystal-chemical and morphological similarities between parent and neoformed phases together with knowledge of the environmental conditions. These two mechanisms, however, may be at both ends of the spectrum of those operating and many transformations may take place through a mixture of the two mechanisms, generating observable elements that are characteristic of one or the other. In the present literature, the boundaries between the two mechanisms are not clear, mainly because dissolution-precipitation is sometimes defined at nearly atomic scale. It is proposed here that such small-scale processes are considered as a solid-state transformation, and that dissolution-precipitation requires dissolution of entire mineral particles and their dissolved species to pass into the bulk of the solution. Understanding the reaction mechanisms of diagenetic transformations is an important issue because they impinge on geochemical conditions and variables such as cation mobility, rock volume, fabric changes, rock permeability, stable isotope signature and phyllosilicate crystal-chemistry.I propose that, in the lower range temperatures at which clay mineral transformations take place, energy considerations favour solid-state transformation, or reactions that involve the breaking of a limited number of bonds, over dissolution of entire grains and precipitation of crystals of the new phase. Large morphological changes are frequently invoked as evidence for a dissolution-precipitation mechanism but changes in particle shape and size may be achieved by particle rupture, particle welding or by hybrid processes in which dissolution-precipitation plays a minor role.Past and recent studies of phyllosilicate transformations show chemical and structural intermediates indicating a large crystal-chemical versatility, greater than is commonly recognized. These intermediates include tetrahedral sheets of different composition within TOT units (termed polar layers), dioctahedral and trioctahedral domains in the same layer, and 2:1 and 1:1 domains also within the same layers. The existence of such intermediate structures suggests that the reaction mechanisms that generated them are within the realm of the solid-state transformation processes.

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
Sign in / Sign up

Export Citation Format

Share Document