The Mechanisms of Racemization of the 2,2'-Bipyridinebis-(1,10-phenanthroline) nickel(II) Ion and the 1,10-Phenanthrolinebis-(2,2'-bipyridine)-nickel(II) Ion

1963 ◽  
Vol 16 (1) ◽  
pp. 51 ◽  
Author(s):  
JA Broomhead ◽  
FP Dwyer
Keyword(s):  
Acid Solution ◽  
Organic Solvents ◽  
Intermolecular Mechanism ◽  
Basic Solutions ◽  
Bipyridine Ligand

The rates of racemization of the 1,10-phenanthrolinebis-(2,2'-bipyridine)nickel(II) ion and the 2,2'-bipyridinebis-(1,10-phenanthroline)nickel(II) ion have been measured in neutral, acid, and basic solutions as well as in organic solvents. Comparison of the rates in acid solution with the corresponding rates of dissociation has shown that racemization takes place by means of an intermolecular mechanism with the loss of one bipyridine ligand. Increased racemization rates in the presence of acids, bases, and specific ions such as NO2-;, Cl-, Br- have been accounted for by the same mechanism.

Darstellung und Schwingungsspektren von Alkyl-und Rhodanohydrohexaboraten / Preparation and Vibrational Spectra of Alkyl and Rhodano Hydrohexaborates

1988 ◽  
Vol 43 (10) ◽  
pp. 1327-1331 ◽  
Author(s):  
A Heinrich ◽  
W Preetz
Keyword(s):  
Frequency Shift ◽  
Raman Spectra ◽  
Organic Solvents ◽  
Vibrational Spectra ◽  
High Frequency ◽  
Acidity Constants ◽  
High Frequency Shift ◽  
Basic Solutions ◽  
Stretching Vibrations ◽  
Ir And Raman

Treatment of B6H62- with iodoalkanes and (SCN)2 in organic solvents affords the monosubstituted protonated hexaborates RB6H6-, R = CH3, C2H5< C3H7, C4H9, C8H17 and SCN, respectively. The acidity constants of these weak Brönsted acids range for the alkylated species from 8.8 to 9.6, and for R = SCN the pka value is ~5. From basic solutions the salts Cs2RB6H5 can be precipitated, which show band patterns in the IR and Raman spectra typical for monosubstituted hydrohexaborates. The protonated compounds RB6H6- are distinguished from the corresponding Brönsted bases RB6H52- by a high frequency shift of the BH stretching vibrations in the order of 100 cm-1. For Cs2(SCN)B6H5, S coordination of SCN- is supposed because of the high frequency of νCN: 2144 cm-1.

scholarly journals The Mixtures of 2.4-Dinitrophenylhidrazones of Inferior Carbonyl Compounds and their HPLC Separation with Gradient Binary Mixtures Phases

2008 ◽  
Vol 3 (1) ◽  
pp. 52-55
Author(s):  
Gheorghe Zgherea
Keyword(s):  
Liquid Chromatography ◽  
Acid Solution ◽  
Organic Compounds ◽  
Binary Mixtures ◽  
Organic Solvents ◽  
Boiling Point ◽  
Carbonyl Compounds ◽  
Hplc Separation ◽  
Reverse Phase ◽  
Theoretical Considerations

Mixtures of small quantities of carbonyl compounds are presents in foods, concerning sensorial qualities. The inferior carbonyl compounds (C2-C4, boiling point <100°C) – mono and dicarbonyl – can be identified and measured their concentrations, after a separation by distillation on the water bath. They are transferred in a strongly acid solution of 2.4-dinitrophenylhidrazine (2.4-DNPH), generating a mixture of insoluble 2.4-dinitrophenylhidrazones (2.4-DNPH-ones). The 2.4-DNPH-ones are organic compounds with weak polarity, solids, crystallized, yellows and water insoluble, soluble in organic solvents. The mixture of 2.4dinitrophenylhidrazones may be separated by liquid chromatography, using the reverse phase mechanism [1-3]. This paper contains experimental and theoretical considerations to the means of separation through liquid chromatography of two synthetically and a natural mixtures that contain 2.4-DNPH-ones provided by inferior carbonyl compounds; to obtain conclude results, in the synthetically mixtures was introduce and 2.4-DNPH-ones provided by carbonyl compounds having three (acetone and propanal) and four (isobutyl aldehyde) atoms of carbon.

scholarly journals An overview: Importance of lignin and different analytical approaches to de-lignify it from plants

2021 ◽  
Vol 8 (3) ◽  
pp. 119-129
Author(s):  
Zeyad Fadhil ◽  
Dheaa Shamikh Zageer ◽  
Abbas Hasan Faris ◽  
Mohammed H Al-Mashhadani
Keyword(s):  
Organic Solvent ◽  
Organic Solvents ◽  
Alkaline Solution ◽  
Analytical Methods ◽  
Chemical Structure ◽  
Short Review ◽  
Kraft Pulping ◽  
Separation Process ◽  
Basic Solutions ◽  
Analytical Approaches

In this short review, it is going to discuss the chemical structure of lignin. Hence the chemical structure of lignin is phenolic high crossed linking polymer so this type of polymers has high rigidity and not so easy to decay. Thus Lignin is insoluble in most organic solvent and water but slightly soluble in basic solutions. Mono-lignols are monomers to form crosslink polymer (lignin) and there are three main types (paracoumaryl. coniferyl and sinapyl) of these monomers. Lignin’s separation process is called delignification which is the procedure of extraction lignin from botanical source. Several analytical methods have been reviewed of delignification process and the most two common approaches are kraft pulping process by utilizing alkaline solution and organosolv pulping process by utilizing organic solvents.

FLUORESCENCE OF AZOTOBACTER: I. A COMPARISON OF THE FLUORESCENT PIGMENTS WITH RIBOFLAVIN

1959 ◽  
Vol 5 (3) ◽  
pp. 299-304 ◽  
Author(s):  
D. B. Johnstone ◽  
M. Pfeffer ◽  
G. C. Blanchard
Keyword(s):  
Acid Solution ◽  
Organic Solvents ◽  
Alkaline Solution ◽  
Paper Electrophoresis ◽  
Water Soluble ◽  
Absorption Peak ◽  
Partial Purification ◽  
Acid Electrolyte ◽  
Riboflavin Production ◽  
Marked Fluorescence

The fluorescent pigments elaborated in cultures of certain species of Azotobacter were compared with riboflavin produced by the same cultures. No correlation between the amounts of fluorescence and riboflavin was observed. Iron appears to inhibit the synthesis of the fluorescent pigments but stimulates riboflavin production. The fluorescent pigments obtained from Azotobacter were water-soluble, thermostable, insoluble in water-free organic solvents, and each exhibited a single absorption peak in the region of 370–380 mμ in slightly acid solution shifting to 400–420 in alkaline solution. Partial purification has been achieved by continuous paper electrophoresis with an acid electrolyte. These studies appear to indicate that the marked fluorescence observed in certain Azotobacter cultures cannot be attributed to riboflavin.

Extended Preservation of Iron for Transmission

1967 ◽  
Vol 25 ◽  
pp. 354-355
Author(s):  
E. P. Abrahamson II ◽  
M. W. Dumais
Keyword(s):  
Acid Solution ◽  
Perchloric Acid ◽  
Microscopy Study ◽  
Perchloric Acid Solution ◽  
Transmission Microscopy ◽  
Iron Base ◽  
Cold Stage

In a transmission microscopy study of iron and dilute iron base alloys, it was determined that it is possible to preserve specimens for extended periods of time. Our specimens were prepunched from 5 to 8 mil sheet to microscope size and annealed for several hours at 700°C. They were then thinned in a glacial acetic-12 percent perchloric acid solution using 10 volts and 20 milliamperes, at a temperature of 8 to 14°C.It was noted that by the use of a cold stage, the same specimen can be observed for periods up to one week without excess contamination. When removal of the specimen from the column becomes necessary, it was observed that a specimen may be kept for later observation in 1,2 dichloroethene or methanol for periods in excess of two weeks.

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