Solvent effects on infra-red group frequencies

1960 ◽  
Vol 255 (1280) ◽  
pp. 22-32 ◽  
Keyword(s):  
Solvent Effects ◽  
Carbonyl Compounds ◽  
Relative Frequency ◽  
Frequency Shifts ◽  
Wide Range ◽  
Infra Red ◽  
Linear Plot

In previous publications we have shown that solvent effects on group frequencies can be studied conveniently by plotting the relative frequency shifts ∆ ν/ν of one solute in a series of solvents, directly against the corresponding values for some other (Bellamy, Hallam & Williams 1958). Thus, ∆ ν/ν the values for the NH stretching frequency of pyrrole yield a linear plot against the ∆ ν/ν values for any other X —H stretching absorption such as the O—H of methanol or the B—H of decaborane. These relations hold over a wide range of different solvents, and each X H compound has a characteristic slope when plotted in this way against a common standard. The slopes measure the relative proton donating powers of the solutes. Similar plots have been obtained for a large number of carbonyl compounds (Bellamy & Williams 1958). Here the pattern of solvent effects is altogether different from that given by X —H links as the dipole available for solvent association is reversed. The sensitivity of individual carbonyl compounds to solvent effects varies widely and seems to depend upon a number of different factors.

α-Alkoxyalkyl Triphenylphosphonium Salts: Synthesis and Reactions

2019 ◽  
Vol 23 (16) ◽  
pp. 1738-1755
Author(s):  
Humaira Y. Gondal ◽  
Zain M. Cheema ◽  
Abdul R. Raza ◽  
Ahmed Abbaskhan ◽  
M. I. Chaudhary
Keyword(s):  
Carbonyl Compounds ◽  
Claisen Rearrangement ◽  
Alder Reaction ◽  
Coupling Reactions ◽  
Phosphonium Salts ◽  
Organic Transformations ◽  
Enol Ethers ◽  
Wide Range ◽  
Synthetic Methodologies ◽  
Alkoxy Groups

Following numerous applications of Wittig reaction now functionalized phosphonium salts are gaining attention due to their characteristic properties and diverse reactivity. This review is focused on α-alkoxyalkyl triphenylphosphonium salts: an important class of functionalized phosphonium salts. Alkoxymethyltriphenylphosphonium salts are majorly employed in the carbon homologation of carbonyl compounds and preparation of enol ethers. Their methylene insertion strategy is extensively demonstrated in the total synthesis of a wide range of natural products and other important organic molecules. Similarly enol ethers prepared thereof are important precursors for different organic transformations like Diels-Alder reaction, Claisen rearrangement, Coupling reactions, Olefin metathesis and Nazarov cyclization. Reactivity of these α-alkoxyalkylphosphonium salts have also been studied in the nucleophilic substitution reactions. A distinctive application of this class of phosphonium salts was recently reported in the phenylation of carbonyl compounds under very mild conditions. Synthesis of structurally diverse alkoxymethyltriphenylphosphonium salts with variation in alkoxy groups as well as counter anions are reported in literature. Here we present a detailed account of different synthetic methodologies for the preparation of this unique class of quaternary phosphonium salts and their applications in organic synthesis.

scholarly journals Enamine/Transition Metal Combined Catalysis: Catalytic Transformations Involving Organometallic Electrophilic Intermediates

2019 ◽  
Vol 377 (6) ◽  
Author(s):  
Samson Afewerki ◽  
Armando Córdova
Keyword(s):  
Transition Metal ◽  
Metal Complex ◽  
Carbonyl Compounds ◽  
Transition Metal Catalysis ◽  
Chemical Transformations ◽  
Considerable Effort ◽  
Metal Catalysis ◽  
First Report ◽  
Wide Range ◽  
Selective Chemical

AbstractThe concept of merging enamine activation catalysis with transition metal catalysis is an important strategy, which allows for selective chemical transformations not accessible without this combination. The amine catalyst activates the carbonyl compounds through the formation of a reactive nucleophilic enamine intermediate and, in parallel, the transition metal activates a wide range of functionalities such as allylic substrates through the formation of reactive electrophilic π-allyl-metal complex. Since the first report of this strategy in 2006, considerable effort has been devoted to the successful advancement of this technology. In this chapter, these findings are highlighted and discussed.

Ether Synthesis through Reductive Cross-Coupling of Ketones with Alcohols Using Me2SiHCl as both Reductant and Lewis Acid

Synlett ◽  
2017 ◽  
Vol 28 (18) ◽  
pp. 2425-2428 ◽  
Author(s):  
Bill Morandi ◽  
Yong Lee
Keyword(s):  
Functional Groups ◽  
Lewis Acid ◽  
Carbonyl Compounds ◽  
Cross Coupling ◽  
Wide Range ◽  
Direct Cross ◽  
Sterically Hindered ◽  
Polar Functional Groups ◽  
Ether Synthesis ◽  
Dialkyl Ethers

We report that a Lewis acidic silane, Me2SiHCl, can mediate the direct cross-coupling of a wide range of carbonyl compounds with alcohols to form dialkyl ethers. The reaction is operationally simple, tolerates a range of polar functional groups, can be utilized to make sterically hindered ethers, and is extendable to sulfur and nitrogen nucleo­philes.

scholarly journals Comparison of methods for solving the vibrational Schrödinger equation in the course of sequential Monte-Carlo-quantum mechanical treatment of hydroxide ion hydration

2010 ◽  
Vol 29 (2) ◽  
pp. 203
Author(s):  
Jasmina Petreska ◽  
Ljupco Pejov
Keyword(s):  
Sequential Monte Carlo ◽  
Reference Method ◽  
Hamiltonian Matrix ◽  
Ion Hydration ◽  
Hydroxide Ion ◽  
Frequency Shifts ◽  
One Dimensional ◽  
Quantum Mechanical Treatment ◽  
Wide Range ◽  
Matrix Diagonalization

Three numerical methods were applied to compute the anharmonic O–H stretching vibrational frequencies of the free and aqueous hydroxide ion on the basis of one-dimensional vibrational potential energies computed at various levels of theory: i) simple Hamiltonian matrix diagonalization technique, based on representation of the vibrational potential in Simons-Parr-Finlan (SPF) coordinates, ii) Numerov algorithm and iii) Fourier grid Hamiltonian method (FGH).Considering the Numerov algorithm as a reference method, the diagonalization technique performs remarkably well in a very wide range of frequencies and frequency shifts (up to 300 cm–1). FGH method, on the other hand, though showing a very good performance as well, exhibits more significant (and non-uniform) discrepancies with the Numerov algorithm, even for rather modest frequency shifts.

Peculiarities of Photorefractive Response in Planar Waveguides Fabricated by Combined Proton and Copper Exchange

1997 ◽  
Vol 06 (03) ◽  
pp. 321-331 ◽  
Author(s):  
Sergey Kostritskii
Keyword(s):  
Experimental Investigation ◽  
Photorefractive Effect ◽  
Planar Waveguides ◽  
Ionic Exchange ◽  
Wide Range ◽  
Infra Red ◽  
Anomalous Character ◽  
A New Technique ◽  
Fabrication Parameters ◽  
Copper Exchange

In this work a photorefractive effect in proton-exchanged planar waveguides on LiNbO 3 crystals is discussed. These waveguides are doped by copper with the aid of a new technique using the low-temperature ionic exchange. The experimental investigation has revealed the anomalous character of the photorefractive response in strongly doped waveguides. Photorefractive measurements are made over a wide range of H +, Cu + and Cu 2+ concentrations, altered by a seriesof oxidation treatments caused by back ionic exchange. Fabrication parameters allowing the realization of high photorefractive sensitivity either in visible or near infra-red ranges are identified.

Solvent Effects on the IR Spectra of N-Methylacetamide

1981 ◽  
Vol 36 (6) ◽  
pp. 763-764 ◽  
Author(s):  
J. Manzur ◽  
G. González
Keyword(s):  
Ir Spectra ◽  
Solvent Effect ◽  
Solvent Effects ◽  
Mutual Influence ◽  
Frequency Shifts ◽  
Donor And Acceptor ◽  
Two Parameters ◽  
Ir Bands

Abstract The solvent effect on the v(N-H) amide I and amide II IR bands of N-methylacetamide were investigated. The frequency shifts could be related to the solvent donor and acceptor num-bers by mean of a two parameters relationship that accounts for the mutual influence between the two interacting sites of the amide.

The Infrared Absorption Spectra of Some Samarium Diketo-ester Complexes

1970 ◽  
Vol 25 (2) ◽  
pp. 139-141 ◽  
Author(s):  
S. P. Tandon ◽  
P. C. Mehta
Keyword(s):  
Coordination Number ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Relative Frequency ◽  
Methyl Acetoacetate ◽  
Frequency Shifts ◽  
Modes Of Vibration ◽  
Infrared Absorption Spectra ◽  
Stretching Vibrations ◽  
First Time

Infrared absorption spectra of some four- and five-coordinated (ethyl 1-methyl acetoacetate) complexes of trivalent samarium have been studied in the region 4000 - 250 cm-1 for the first time. About twenty bands in each chelate have been observed and assigned to different modes of vibration. A study of relative frequency shifts of CO stretching vibrations reveals that the metal-oxygen bonds in all the complexes are nearly of the same strength. The vibrational frequencies, with few exceptions, are found to be nearly independent of the coordination number of the metal.

scholarly journals Interaction of solvents with membranal and soluble potassium ion-dependent enzymes

1970 ◽  
Vol 116 (1) ◽  
pp. 49-54 ◽  
Author(s):  
M. Mayer ◽  
Y. Avi-Dor
Keyword(s):  
Enzyme Activity ◽  
Pyruvate Kinase ◽  
Solvent Effects ◽  
Adenosine Triphosphatase ◽  
The State ◽  
Dimethyl Sulphoxide ◽  
The Other ◽  
Enzyme Structure ◽  
Wide Range ◽  
Muscle Pyruvate Kinase

The effects of dimethyl sulphoxide and glycerol on ox brain microsomal Na++K+-stimulated adenosine triphosphatase (EC 3.6.1.3), K+-stimulated p-nitrophenyl phosphatase and K+-dependent muscle pyruvate kinase (EC 2.7.1.40) were studied. Dimethyl sulphoxide at concentrations below 20% (v/v) was found to stimulate the p-nitrophenyl phosphatase and pyruvate kinase by increasing their affinity for K+ but to inhibit the Na++K+-stimulated adenosine triphosphatase. The latter enzyme activity was also inhibited by glycerol, which like dimethyl sulphoxide, stimulated the K+-activated p-nitrophenyl phosphatase at a wide range of concentrations. The solvent effects were promptly reversed by dilution. Similarity was found between glycerol and dimethyl sulphoxide, on one hand, and ATP, on the other, in their stimulatory effect and their ability to increase the ouabain- and oligomycin-sensitivity of the K+-stimulated p-nitrophenyl phosphatase. However, only the solvents, not the ATP, increased the binding of K+ by the microsomes. From the above findings it is suggested that solvents may act on K+-dependent enzymes by altering the state of solvation of the activating cation as well as by changing the enzyme structure.

scholarly journals Glyoxalase III from Escherichia coli: a single novel enzyme for the conversion of methylglyoxal into d-lactate without reduced glutathione

1995 ◽  
Vol 305 (3) ◽  
pp. 999-1003 ◽  
Author(s):  
K Misra ◽  
A B Banerjee ◽  
S Ray ◽  
M Ray
Keyword(s):  
Escherichia Coli ◽  
Active Site ◽  
Carbonyl Compounds ◽  
Reduced Glutathione ◽  
Thiol Group ◽  
Glyoxalase I ◽  
Ph Optimum ◽  
Native Form ◽  
Wide Range ◽  
Glyoxalase Iii

A single novel enzyme, glyoxalase III, which catalyses the conversion of methylglyoxal into D-lactate without involvement of GSH, has been detected in and purified from Escherichia coli. Of several carbonyl compounds tested, only the alpha-ketoaldehydes methylglyoxal and phenylglyoxal were found to be substrates for this enzyme. Glyoxalase III is active over a wide range of pH with no sharp pH optimum. In its native form it has an M(r) of 82000 +/- 2000, and it is composed of two subunits of equal M(r). Glutathione analogues, which are inhibitors of glyoxalase I, do not inhibit glyoxalase III. Glyoxalase III is found to be sensitive to thiol-blocking reagents. The p-hydroxymercuribenzoate-inactivated enzyme could be almost completely re-activated by dithiothreitol and other thiol-group-containing compounds, indicating the possible involvement of thiol group(s) at or near the active site of the enzyme.

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