Titrations in non-aqueous media. Part XIII. Potentiometric and conductimetric titrations of α-amino acids with perchloric acid in acetic acid and acetonitrile-acetic acid solvents

The Analyst ◽  
1988 ◽  
Vol 113 (8) ◽  
pp. 1313-1316 ◽  
Author(s):  
Turgut Gündüz ◽  
Esma Kılıç ◽  
Fitnat Köseoğlu ◽  
S. Gül Öztaş
Keyword(s):  
Amino Acids ◽  
Acetic Acid ◽  
Perchloric Acid ◽  
Aqueous Media

scholarly journals Differential Electrolytic Potentiometric Determination of Some Amino Acids in Dosage Forms

2004 ◽  
Vol 87 (3) ◽  
pp. 671-676
Author(s):  
Sheikha M Al-Ghannam ◽  
Abdalla M S Abulkibash ◽  
Abeer M Al-Olyyan
Keyword(s):  
Amino Acids ◽  
Acetic Acid ◽  
Direct Current ◽  
Current Density ◽  
Perchloric Acid ◽  
Dosage Forms ◽  
Basic Character ◽  
Direct Titration ◽  
Titration Curves

Abstract The application of direct-current differential electrolytic potentiometry to the nonaqueous titration of amino acids was investigated. The basic character of amino acids in acetic acid was enhanced to permit their direct titration with perchloric acid. A pair of antimony electrodes was used as an indicating system. The shapes of the titration curves obtained were almost symmetrical with sharp peaks. The optimum current density for those titrations was found to be 1–2 μA/cm2. The procedure was applied successfully to the determination of certain amino acids in drug formulations, and the results were favorably compared statistically with those obtained by official methods.

Racemization rates of 3,4-didehydro-2-amino acids

1989 ◽  
Vol 54 (12) ◽  
pp. 3381-3386 ◽  
Author(s):  
Libor Havlíček ◽  
Jan Hanuš ◽  
Jan Němeček
Keyword(s):  
Amino Acids ◽  
Acetic Acid ◽  
Acidic Medium

The racemization rates of amino acids in acidic medium (acetic acid) were studied. The sensitivity to racemization decreases in the order (E)-3,4-didehydroornithine > (E)-Nδ-Z-3,4-didehydroornithine >> (Z)-3,4-didehydronorvaline > ornithine, norvaline. (E)-3,4-Didehydroornithine is also relatively rapidly racemized on heating with 5 M or 0.05 M-HCl (100 °C).

scholarly journals Nitration of Jharia basin coals, India: a study of structural modifications by XRD and FTIR techniques

2021 ◽  
Author(s):  
Prabal Boral ◽  
Atul K. Varma ◽  
Sudip Maity
Keyword(s):  
Acetic Acid ◽  
Nitric Acid ◽  
Linear Relationship ◽  
Glacial Acetic Acid ◽  
Vitrinite Reflectance ◽  
Aqueous Media ◽  
Interlayer Spacing ◽  
Acetic Acid Medium ◽  
X Ray ◽  
The Media

AbstractFour coal samples from Jharia basin, India are treated with nitric acid in glacial acetic acid and aqueous media to find out the chemical, petrographic and spatial structure of the organic mass by X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) techniques. X-ray parameters of coal like interlayer spacing (d002), crystallite size (Lc), aroamticity (fa), average number of aromatic layers (Nc), and coal rank (I26/I20) have been determined using profile-fitting software. Considerable variation is observed in treated coals in comparison to the demineralized coals. The d002 values of treated coals have increased in both the media showing increase in disordering of organic moieties. A linear relationship has been observed between d002 values with the volatile matter of the coals. Similarly, the d002 values show linear relationship with Cdmf contents for demineralized as well as for the treated coals in both the media. The Lc and Nc values have decreased in treated coals corresponding to demineralized coals. The present study shows that nitration in both the media is capable of removing the aliphatic side chains from the coals and aromaticity (fa) increases with increase in rank and shows a linear relationship with the vitrinite reflectance. The corresponding I26/I20 values are least for treated coals in glacial acetic acid medium followed by raw and then to treated coals in aqueous medium. FTIR studies show that coal arenes of the raw coals are converted into nitro-arenes in structurally modified coals (SMCs) in both the media, the corresponding bands at 1550–1490 and 1355–1315 cm−1 respectively. FTIR study confirms that nitration is the predominant phenomenon, though, oxidation and nitration phenomena takes place simultaneously during treatment with nitric acid to form SMCs. In comparison to raw coals, the SMCs show higher aromaticity and may be easily converted to coal derived products like activated carbon and specialty carbon materials.

scholarly journals Alum Catalyzed Simple, Efficient, and Green Synthesis of 2-[3-Amino-5-methyl-5-(pyridin-3-yl)-1,5-dihydro-4H-1,2,4-triazol-4-yl]propanoic Acid Derivatives in Aqueous Media

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Harshita Sachdeva ◽  
Diksha Dwivedi ◽  
Rekha Saroj
Keyword(s):  
Amino Acids ◽  
Green Chemistry ◽  
Green Synthesis ◽  
Aqueous Media ◽  
Propanoic Acid ◽  
Ft Ir ◽  
C Nmr

Alum (KAl(SO4)2·12H2O) is an inexpensive, efficient, and nontoxic catalyst used for the synthesis of 2-[3-amino-5-methyl-5-(pyridin-3-yl)-1,5-dihydro-4H-1,2,4-triazol-4-yl]propanoic acid derivatives in aqueous media by the reaction of 3-acetyl pyridine(1), amino acids(2)/(6), and thiosemicarbazide(4)at 80°C. This methodology offers significant improvements for the synthesis of products with regards to the yield of products, simplicity in operation, and green aspects by avoiding toxic catalysts which uphold the motto of green chemistry. Synthesized compounds have been characterized by FT-IR,13C NMR, and1HNMR spectroscopy.

Solid Phase Synthesis of a Somatostatin Amide Analogue Using Acid Labile t-Bumeoc Protection and an Acid Labile Anchor Group

1992 ◽  
Vol 57 (8) ◽  
pp. 1707-1718
Author(s):  
Wolfgang Voelter ◽  
Gerhard Breipohl ◽  
Chryssa Tzougraki ◽  
Eveline Jungfleisch-Turgut
Keyword(s):  
Amino Acids ◽  
Acetic Acid ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
Somatostatin Analogue ◽  
Phase Synthesis ◽  
Anchor Group ◽  
Amide Form ◽  
Polystyrene Resin ◽  
Acid Labile

The solid phase synthesis of an amidated somatostatin analogue based on the principle of differentiated acidolysis is described. The acid labile and smoothly cleavable t-Bumeoc moiety (1% TFA/DCM) is used for temporary Nα-protection of D- and L-amino acids and [4-[[[9H-fluoren-9-yl-methoxycarbonyl]amino](4-methoxyphenyl)methyl]-2-methylphenoxy]acetic acid, attached to an aminomethylated polystyrene resin is used as acid sensitive linker of the solid carrier which releases the peptide in its amide form by treatment with TFA. Its preparation is described in detail.

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