Phosphorus-31 NMR spectroscopic analysis of labile hydrogen functional groups: identification with a dithiaphospholane reagent

1990 ◽  
Vol 4 (2) ◽  
pp. 197-201 ◽  
Author(s):  
C. Lensink ◽  
J. G. Verkade
Keyword(s):  
Functional Groups ◽  
Spectroscopic Analysis ◽  
Labile Hydrogen

scholarly journals Synthesis, stability, and reactivity of mesoionic carbene iridium dihydride complexes

2020 ◽  
Author(s):  
Marta Olivares ◽  
Martin Albrecht
Keyword(s):  
Electronic Properties ◽  
Functional Groups ◽  
Pyridine Ring ◽  
Spectroscopic Analysis ◽  
Pka Values ◽  
Trans Effect ◽  
Structural Assignment ◽  
Wide Range ◽  
Hydride Metal ◽  
The Stability

Pyridyl-triazolylidene ligands with variable donor properties were used as tunable ligands at a dihydride iridium(III) center. The straightforward synthesis of this type of ligand allows for an easy incorporation of electron donating substituents in different positions of the pyridine ring or different functional groups such as esters, alkoxy or aliphatic chains on the C4 position of the triazole heterocycle. The stability of these hydride metal systems allowed these complexes to be used as models for studying the influence of the ligand modifications on hydride reactivity. Spectroscopic analysis provided unambiguous structural assignment of the dihydride system. Modulation of the electronic properties of the wingtip substituents did not appreciably alter the reactivity of the hydrides. Reactivity studies using acids with a wide range of pKa values indicated a correlation between hydride reactivity and acidity and showed exclusive reactivity towards the less shielded hydride trans to the carbene carbon rather than the more shielded hydride trans to the pyridine ring, suggesting that the trans effect is more relevant in these reactions than the NMR spectroscopically deduced hydridic character.

scholarly journals Studies on Contributions of FTIR Spectroscopic analysis in the Puriৎication process of Veeram (Hg2Cl2) used in Siddha formulations

2020 ◽  
Vol 11 (SPL4) ◽  
pp. 1251-1259
Author(s):  
Madhavan R ◽  
Muthukumar N J ◽  
Savariraj Sagayam C ◽  
Rajalakshmi P ◽  
Brindha P
Keyword(s):  
Rheumatoid Arthritis ◽  
Ftir Spectroscopy ◽  
Functional Groups ◽  
Spectroscopic Analysis ◽  
Lemon Juice ◽  
Ftir Analysis ◽  
Chemical Formula ◽  
Chemical Changes ◽  
Before And After ◽  
Tender Coconut

In Siddha system Arsenics are called as Paasaanam (toxins). Veeram is one of the paasaanam, its chemical formula is Hg2Cl2 (Calomel). Internally arsenic based medicines are used for rheumatoid arthritis, generalized body pain, syphilis, epilepsy and cancer.Various organic agents are used to purify the veeram such as milk, tender coconut, bitter guard and lemon juice. In this study raw veeram and products obtained after purification were analyzed using FTIR Spectroscopy with a view to understand the need and mechanism of this purification processes. FTIR analysis was carried out before and after purification. Efforts were made to study various chemical changes veeram undergoes during this process. FTIR of the raw Veeram and its processed samples were recorded between 4000-400cm-1. In the study raw drug showed only nine functional groups in the region between 3789.36cm-1 and 468.75cm-1. Bitter gourd treated veeram peaks  were observed in the region between 3526.99 and 476.62cm-1 and a total of 13-peaks were obtained.  Milk treated veeram showed peaks in the region between 3851.10 and 470.39cm-1 and total of 16- peaks were obtained. This method indicated presence of large number of functional groups. Lemon juice treated veeram showed peaks in between 3839.33 and 471.99cm-1  total of 15-peaks were obtained. Tender coconut veeram peaks were observed in between 3877.84 and 477.33cm-1  and total of 15-peaks were obtained. From this data number of functional groups increased in purified samples which indicated that the toxic veeram is not only detoxified but also interacted with functional groups of purifying agents there by therapeutic potency is enhanced.

A Vibrational Spectroscopic Analysis of the Structure of Natural Rubber

1987 ◽  
Vol 60 (4) ◽  
pp. 647-658 ◽  
Author(s):  
F. J. Lu ◽  
S. L. Hsu
Keyword(s):  
Natural Rubber ◽  
Functional Groups ◽  
Spectroscopic Analysis ◽  
Extraction Solvent ◽  
Gel Fraction ◽  
Gel Phase ◽  
Composition Structure ◽  
Vulcanization Process ◽  
Structural Aspects ◽  
Soluble Part

Abstract It is not an overstatement to say that natural rubber (NR) is one of the most used polymers. There are numerous studies dealing with the structural aspects of rubber which give rise to its elastic property. However, it should be emphasized that the majority of these studies are generally concerned with rubber in the vulcanized state or, in fact, dealing with the vulcanization process. Relatively few studies have actually been directed at a better understanding of the composition, structure, and properties of raw rubber. This area of study is also important because the composition and the structure of NR differ from synthetic polyisoprene in that the presence of functional groups on main chains and nonrubbery materials, such as proteins, can significantly affect the rheological properties and the processing conditions of rubber before the vulcanization process. Raw rubber can be divided into two different fractions, sol (soluble part) and gel (insoluble part). Of course, this definition depends somewhat on the solvent used. Even though the main chain in both portions of rubber are chemically similar, their significantly distinct mechanical properties have, in fact, been attributed to the nonrubbery materials such as proteins interacting with isoprene chains. It is generally accepted that the amount of nonrubbery materials in the gel fraction is much higher than the sol fraction. The protein apparently interacts quite strongly with specific functional groups on the isoprene chain and is difficult to remove from the gel phase by physical means. It is probable that the different properties between sol and gel rubber is due to the amount of crosslinking of the main chains, but several aspects of the structure need to be answered in greater detail. We know, for example, that the amount of gel fraction can change as a function of extraction solvent. Therefore, one cannot conclude that the interaction between rubber chains even in the gel fraction is strictly chemical in nature. Our premise is that the protein is an important component connecting the isoprene chains.

Phosphorus-31 NMR spectroscopic analysis of coal pyrolysis condensates and extracts for heteroatom functionalities possessing labile hydrogen

1988 ◽  
Vol 2 (6) ◽  
pp. 765-774 ◽  
Author(s):  
A. E. Wroblewski ◽  
C. Lensink ◽  
R. Markuszewski ◽  
John G. Verkade
Keyword(s):  
Spectroscopic Analysis ◽  
Labile Hydrogen ◽  
Coal Pyrolysis

scholarly journals Investigating the solid-state assembly of pharmaceutically-relevant N,N-dimethyl-O-thiocarbamates in the absence of labile hydrogen bonds

CrystEngComm ◽  
2020 ◽  
Vol 22 (48) ◽  
pp. 8290-8298
Author(s):  
Davin Tan ◽  
Zi Xuan Ng ◽  
Rakesh Ganguly ◽  
Yongxin Li ◽  
Han Sen Soo ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Hydrogen Bonds ◽  
Functional Groups ◽  
Labile Hydrogen ◽  
Active Pharmaceutical Ingredients ◽  
Hydrogen Bond Donor ◽  
Pharmaceutical Ingredients

There are many active pharmaceutical ingredients that lack N–H, O–H and S–H hydrogen-bond donor functional groups.

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