Coordination RC6 H4 S(CH2 )8 SC6 H4 R/(CuI) n Polymers (R (n ) = H (4); Me (8)): An Innocent Methyl Group that Makes the Difference

2015 ◽  
Vol 36 (7) ◽  
pp. 654-659 ◽  
Author(s):  
Pierre D. Harvey ◽  
Antoine Bonnot ◽  
Antony Lapprand ◽  
Carsten Strohmann ◽  
Michael Knorr
Keyword(s):  
Methyl Group ◽  
The Difference

scholarly journals Unusual Regularity in GC Retention of Simple Amino Acid Derivatives

2019 ◽  
Vol 6 (1) ◽  
pp. 3-14 ◽  
Author(s):  
Igor G. Zenkevich ◽  
Nino G. Todua ◽  
Anzor I. Mikaia
Keyword(s):  
Gas Chromatography ◽  
Retention Index ◽  
Methyl Esters ◽  
Elution Order ◽  
Alkyl Esters ◽  
Methyl Group ◽  
The Difference ◽  
Direct Use ◽  
Derivatives Of

Background: Application of simple regularities and general principles along with direct use of reference gas chromatography retention index data for reliable structure determination of compounds can be enhanced by determination of new regularities that are specific to certain structural elements. Objective: Revelation and interpretation of an anomaly in the elution order of alkyl esters of alkoxycarbonyl derivatives of glycine and alanine on standard and semi-standard non-polar phases. Method: Preliminary derivatization of amino acids to alkyl esters of N-alkoxycarbonyl analogs and interpretation of their gas chromatographic characteristics. Results: Alkyl esters of N-alkoxycarbonyl derivatives of alanine (Alkyl = C2H5, n- and iso-C3H7) elute prior to the same derivatives of glycine, despite the presence of an additional methyl group at C(2) in the molecule. Elution order is reversed for methyl esters of N-methoxycarbonyl derivatives. Conclusion: It is established that the peculiar behavior of alkyl esters of N-alkoxycarbonyl derivatives of glycine and alanine agrees with the concepts of gas chromatography and the known retention index regularities of organic compounds. A decrease of retention index values is a result of an introduction of an additional methyl group to a carbon atom connected to two polar fragments in a molecule like CH2XY. The dependence of the difference of retention index values for homologs of the types of CH3-CHXY and CH2XY vs. the total mass of fragments (X + Y) is similar to those for other sub-groups of analytes.

I. On a new class of bodies homologous to hydrocyanic acid. -I

1868 ◽  
Vol 16 ◽  
pp. 144-147
Keyword(s):  
Acetic Acid ◽  
Formic Acid ◽  
Hydrocyanic Acid ◽  
Methyl Group ◽  
New Class ◽  
Atom Group ◽  
The Difference

The typical transformation which hydrocyanic acid undergoes when sub­mitted, under appropriate circumstances, to the action of water, is capable of assuming two different forms when accomplished in its homologues. If the hydrocyanic molecule be found to fix the elements of two mole­cules of water, yielding ultimately formic acid and ammonia, it is obvious that the atom group which in the homologues of hydrocyanic acid we as­sume in the place of hydrogen may be eliminated when these homologues are decomposed by water in conjunction either with formic acid or with ammonia. To take an example: —When acting with water upon the sim­plest homologue of hydrocyanic acid (upon cyanide of methyl), we may ex­pect to see the methyl-group separating either in the form of methyl-formic, i. e . acetic acid, or in the form of methyl-ammonia, i. e . of methylamine, The difference of the two reactions and their relation to the metamorphosis of hydrocyanic acid itself are exhibited by the following equations:

scholarly journals The metabolism of 3,5-di-tert.-butyl-4-hydroxytoluene in the rat and in man

1968 ◽  
Vol 106 (4) ◽  
pp. 783-790 ◽  
Author(s):  
J W Daniel ◽  
J C Gage ◽  
D. I. Jones
Keyword(s):  
Enterohepatic Circulation ◽  
Minor Component ◽  
Aldehyde Group ◽  
Enzyme Mechanism ◽  
Mercapturic Acid ◽  
Rat Urine ◽  
Methyl Group ◽  
Tert Butyl ◽  
The Difference ◽  
Main Component

1. The major metabolites of 3,5-di-tert.-butyl-4-hydroxytoluene (BHT) in the rat are 3,5-di-tert.-butyl-4-hydroxybenzoic acid (BHT-acid), both free (9% of the dose) and as a glucuronide (15%), and S-(3,5-di-tert.-butyl-4-hydroxybenzyl)-N-acetylcysteine. 2. The mercapturic acid does not appear to derive from the usually accepted enzyme mechanism, and may involve a non-enzymic reaction between BHT free radical and cysteine. 3. The ester glucuronide and mercapturic acid found in rat urine are also the major metabolites in rat bile and must be responsible for the enterohepatic circulation. 4. Free BHT-acid is the main component in rat faeces. 5. In man, BHT-acid, free and conjugated, is a minor component in urine, and the mercapturic acid is virtually absent. The bulk of the radioactivity is excreted as the ether-insoluble glucuronide of a metabolite in which the ring methyl group and one tert.-butyl methyl group are oxidized to carboxyl groups, and a methyl group on the other tert.-butyl group is also oxidized, probably to an aldehyde group. 6. These differences in metabolism by the rat and by man are sufficient to account for the difference in excretion by the two species.

Synthesis and Reactivity Studies of Benzo-Substituted Bis(indenyl) Iron and Zirconium Complexes: The Difference a Methyl Group Can Make

2012 ◽  
Vol 31 (10) ◽  
pp. 3865-3879 ◽  
Author(s):  
Gregory P. McGovern ◽  
Fernando Hung-Low ◽  
Jesse W. Tye ◽  
Christopher A. Bradley
Keyword(s):  
Methyl Group ◽  
Zirconium Complexes ◽  
The Difference

BEZIEHUNGEN ZWISCHEN SUBSTITUTION IM RING A UND ABBAU IM STOFFWECHSEL BEI VERWANDTEN DES TESTOSTERONS

1962 ◽  
Vol 41 (4) ◽  
pp. 494-506 ◽  
Author(s):  
H. Langecker
Keyword(s):  
Double Bond ◽  
Ring System ◽  
Keto Group ◽  
Hydroxyl Group ◽  
Methyl Group ◽  
Structural Peculiarities ◽  
Metabolic Degradation ◽  
The Difference ◽  
Testosterone Metabolites ◽  
Derivatives Of

ABSTRACT Judging from the metabolites found in the urine, 1-methyl-androst-1-en-17β-ol-3-one (methenolone) and testosterone are metabolized in a different manner. For further clarification, other derivatives of testosterone with modifications in Ring A were investigated with regard to the oxidation of the 17-hydroxyl group. The production of urinary 17-ketosteroids decreased in the following sequence: testosterone; 1α-methyltestosterone and androstan-17β-ol-3-one; 1β-methyl-androstan-17β-ol-3-one; 2α-methyl-androstan-17β-ol-3-one and androst-1-en-17β-ol-3-one; 1α-methyl-androstan-17β-ol-3-one; 1-methyl-androsta-1,4-dien-17β-ol-3-one; 1,17α-dimethyl-androst-1-en-17β-ol-3-one and 1 -methyl-androst-1 -en-17β-ol-3-one (methenolone). The difference in metabolic degradation is also demonstrated in the fractionation of the urinary ketones. While after the administration of testosterone practically only hydrogenated 17-ketones are observed in the urine, the unchanged compound is still traceable in remarkable quantities after the administration of methenolone, along with minor quantities of the corresponding diketone. Testosterone-metabolites here are absent, whereas they represent the major substances present after the administration of androst-1-en-17β-ol-3-on. Following the administration of 1α-methyltestosterone only hydrogenated 17-ketones are detected which are still partly methylated. The 1-methyl-group and the Δ 1-double-bond seem to be responsible for the inhibition of the oxidation of methenolone in the 17-position. In addition, the hydrogenation of the double-bond and the reduction of the 3-keto-group are inhibited, obviously on account of the same structural peculiarities. The demethylation of methenolone is also inhibited. Any change in the steroid ring system forms a new substrate, thus producing new conditions for the enzymatic attack in the metabolic degradation.

Optical Property and Photoisomerization of Some Functional Azobenzene Derivatives with Aromatic Substituted Groups

2011 ◽  
Vol 121-126 ◽  
pp. 1009-1013
Author(s):  
Ti Feng Jiao ◽  
Xu Hui Li ◽  
Qiu Rong Li ◽  
Jing Xin Zhou
Keyword(s):  
Molecular Structure ◽  
Optical Property ◽  
Potential Application ◽  
Uv Light ◽  
Molecular Structures ◽  
Functional Material ◽  
Methyl Group ◽  
Uv Light Irradiation ◽  
The Difference ◽  
Azobenzene Derivatives

Some functional azobenzene derivatives with aromatic substituted groups have been synthesized and their photoisomerization have also been investigated. It has been found that depending on different substituted groups, such as phenyl or naphthyl segments, the formed azobenzene derivatives showed different properties, indicating distinct regulation of molecular skeletons. Spectral data confirmed commonly the characteristic absorption of substituted groups and aromatic segments in molecular structures. In addition, the photoisomerization of all compounds in solution can show trans-to-cis photoisomerization by UV light irradiation, and demonstrate distinct isomerization ratio depending on effect of different substituted headgroups. The difference is mainly attributed to the aromatic substituted headgroups and methyl group in molecular structure. The present results have showed that the special properties of azobenzene derivatives could be effectively turned by modifying molecular structures of objective compounds with proper substituted groups, which show potential application in sensor and functional material field.

pKa values of protonated α,β-unsaturated cyclic carboxylic acids. Effect of ring size on acidities

1978 ◽  
Vol 56 (15) ◽  
pp. 2003-2007 ◽  
Author(s):  
S. N. Bhat ◽  
Rama Rao ◽  
K. Ranganayakulu
Keyword(s):  
Double Bond ◽  
Carboxylic Acids ◽  
Acid Strength ◽  
Ring System ◽  
Ring Size ◽  
Methyl Group ◽  
Tiglic Acid ◽  
Conjugate Acid ◽  
The Difference ◽  
Steric Inhibition Of Resonance

The pKa values of protonated α,β-unsaturated acids, namely tiglic, cyclopentene carboxylic, cyclohexene carboxylic, and cycloheptene carboxylic acids have been determined spectrophotometrically and the values are −4.08, −4.05, −3.88, and −3.84, respectively. The conjugate acid of tiglic acid is a stronger acid than that of crotonic acid (pKa − 3.94) and the difference in acid strength is explained on the basis of steric inhibition of resonance by the α-methyl group. All the protonated cyclic acids are shown to be somewhat weaker than the corresponding acyclic ones. Several factors have been considered to explain the acid strength of these cyclic α,β-unsaturated acids. It has been shown that the ease of placing the double bond exo to the ring system is responsible for the changes in acidity of the above cyclic systems.

Bisalkylation Theory of Neoprene Vulcanization

1955 ◽  
Vol 28 (4) ◽  
pp. 1021-1031 ◽  
Author(s):  
Peter Kovacic
Keyword(s):  
Zinc Oxide ◽  
Natural Rubber ◽  
Organic Compounds ◽  
Chlorine Atom ◽  
Structural Difference ◽  
General Purpose ◽  
Active Chlorine ◽  
Functional Difference ◽  
Methyl Group ◽  
The Difference

Abstract Among the organic compounds that are recommended for use with magnesia and zinc oxide as vulcanizing agents for Neoprene are ethylenethiourea (2-imidazolidinethione), p,p′-diaminodiphenylmethane and the di-o-tolylguanidine salt of dicatechol borate. In the absence of sulfur, these agents in combination with zinc oxide do not vulcanize natural rubber. This points up a marked difference in the way these elastomers vulcanize. Although a major structural difference is the chlorine atom in Neoprene in place of the side methyl group in natural rubber, the small amount of tertiary allylic chlorine formed by 1,2-polymerization is the important functional difference. The labile chlorine amounts to about 1.5 per cent of the total chlorine in a general-purpose Neoprene made at 40° C, such as Neoprene Type W used in this work. In Neoprene latex, this active chlorine is gradually liberated, and the polymer becomes cross-linked. This paper demonstrates the importance of the labile chlorine in the vulcanization of dry Neoprene, accounts for the difference in the vulcanization of Neoprene and natural rubber, and suggests a bisalkylation theory of Neoprene vulcanization.

scholarly journals Stereoselective free radical phenylsulfenylation of a nonactivated δ-carbon atom

2004 ◽  
Vol 69 (10) ◽  
pp. 737-747 ◽  
Author(s):  
Goran Petrovic ◽  
Radomir Saicic ◽  
Ljiljana Dosen-Micovic ◽  
Zivorad Cekovic
Keyword(s):  
Free Radical ◽  
Carbon Atom ◽  
Transition State ◽  
Ab Initio ◽  
Absolute Configuration ◽  
Optical Purity ◽  
Methyl Group ◽  
Chiral Carbon ◽  
The Difference ◽  
High Stereoselectivity

A stereoselective free radical introduction of a phenylthio group onto a nonactivated methyl group in the ?-position, adjacent to a prochiral carbon atom, was achieved by photolysis of (-)-menthyl benzenesulfenate in the presence of hexabutylditin and (1R, 3R, 4S, 8S)-9-phenylthiomenthol (4) was obtained with 91%optical purity. High stereoselectivity of the reaction was calculated (ab initio MP2/6-31G**) to be the consequence of the difference in the transition state eneregies (??G# = 5.08 kJ/mol) favouring 4 relative to (1R,3R,4S,8R)-9-phenylthiomenthol (5). The absolute configuration of a the new chiral carbon atom was confirmed by its correlation with the corresponding menthane-3,9-diol of known stereochemistry.

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