ChemInform Abstract: Synthesis and Structure-Optical Rotation Relationships of Homochiral, Monodisperse, Tartaric Acid-Based Dendrimers.

AbstractThe most characteristic hallmark of life is its homochirality: all biomolecules are usually of one hand, e.g. on Earth life uses only L-amino acids for protein synthesis and not their D mirror images. We therefore suggest that a search for extra-terrestrial life can be approached as a Search for Extra- Terrestrial Homochirality (SETH). The natural choice for a SETH instrument is optical rotation, and we describe a novel miniaturized space polarimeter, called the SETH Cigar, which could be used to detect optical rotation as the homochiral signature of life on other planets. Moving parts are avoided by replacing the normal rotating polarizer by multiple fixed polarizers at different angles as in the eye of the bee. We believe that homochirality may be found in the subsurface layers on Mars as a relic of extinct life, and on other solar system bodies as a sign of advanced pre-biotic chemistry. We discuss the chiral GC-MS planned for the Roland lander of the Rosetta mission to a comet and conclude with theories of the physical origin of homochirality.

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Solvent Effect on Optical Rotation I Optical Rotation ofl-Santonin

Zeitschrift für Physikalische Chemie ◽

10.1524/zpch.1960.25.1_2.056 ◽

1960 ◽

Vol 25 (1_2) ◽

pp. 56-68 ◽

Cited By ~ 2

Author(s):

A. J. Mukhedkar

Keyword(s):

Solvent Effect ◽

Optical Rotation

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Full Optical Rotation Tensor at CCSD Level in the Modified Velocity Gauge

10.26434/chemrxiv.13204064.v2 ◽

2020 ◽

Author(s):

Kaihua Zhang ◽

Ty Balduf ◽

Marco Caricato

Keyword(s):

Electric Dipole ◽

Optical Rotation ◽

Electric Quadrupole ◽

Polarizability Tensor ◽

Dipole Polarizability ◽

Difficult Case ◽

Computationally Efficient ◽

Rotation Tensor ◽

Approximate Methods ◽

Velocity Gauge

<div> <div> <p> </p><div> <div> <div> <p>This work presents the first simulations of the full optical rotation (OR) tensor at coupled cluster with single and double excitations (CCSD) level in the modified velocity gauge (MVG) formalism. The CCSD-MVG OR tensor is origin independent, and each tensor element can in principle be related directly to experimental measurements on oriented systems. We compare the CCSD results with those from two density functionals, B3LYP and CAM-B3LYP, on a test set of 22 chiral molecules. The results show that the functionals consistently overestimate the CCSD results for the individual tensor components and for the trace (which is related to the isotropic OR), by 10-20% with CAM-B3LYP and 20-30% with B3LYP. The data show that the contribution of the electric dipole-magnetic dipole polarizability tensor to the OR tensor is on average twice as large as that of the electric dipole-electric quadrupole polarizability tensor. The difficult case of (1S,4S)-(–)-norbornenone also reveals that the evaluation of the former polarizability tensor is more sensitive than the latter. We attribute the better agreement of CAM-B3LYP with CCSD to the ability of this functional to better reproduce electron delocalization compared with B3LYP, consistently with previous reports on isotropic OR. The CCSD-MVG approach allows the computation of reference data of the full OR tensor, which may be used to test more computationally efficient approximate methods that can be employed to study realistic models of optically active materials. </p> </div> </div> </div> </div> </div>

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ANTIPHYTOPATHOGENIC EFFECT OF TARTARIC ACID SYNTHETIC DERIVATIVES

European Journal of Technical and Natural Sciences ◽

10.29013/ejtns-20-3-3-6 ◽

2020 ◽

pp. 3-6

Author(s):

B. G. Babayan ◽

S. A. Bagdasaryan ◽

M. A. Melkumyan ◽

A. R. Mikaelyan

Keyword(s):

Tartaric Acid ◽

Synthetic Derivatives

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Enzymatic Iodination of Maleic and Fumaric Acids Diethyl Esters

Revista de Chimie ◽

10.37358/rc.08.12.2071 ◽

2009 ◽

Vol 59 (12) ◽

pp. 1400-1404

Author(s):

Marius Tudorascu ◽

Spiridon Oprea ◽

Afrodita Doina Marculescu ◽

Stefania Tudorascu

Keyword(s):

Hydrogen Peroxide ◽

Tartaric Acid ◽

Disperse System ◽

Hydrogen Peroxide Solution ◽

Ultrasonic Pretreatment ◽

Tartaric Acids ◽

Inactive Form ◽

Generating System ◽

Sole Product

The mechanism of the enzymatic iodination process of diethylmaleate and diethylfumarate (which present no miscibility with water) in the presence of lactoperoxidase, both in diluted hydrogen peroxide solution and in a generating system of hydrogen peroxide using ammonium and calcium iodides as halide sources in disperse system (after an ultrasonic pretreatment) was studied. The obtained sole product (diethyl-2, 3-diiodosuccinate) after the enzymatic iodination process was directly hydrolyzed to a tartaric acid present in an optically inactive form. The mechanism of obtaining the intermediate and final products and respectively, the existence of both D, L-tartaric acid and meso-tartaric acids (as lithium bitartrates) were also investigated.

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Synthesis and Kinetics of Highly Substituted Piperidines in the Presence of Tartaric Acid as a Catalyst

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207321666180228115130 ◽

2018 ◽

Vol 21 (4) ◽

pp. 302-311

Author(s):

Younes Ghalandarzehi ◽

Mehdi Shahraki ◽

Sayyed M. Habibi-Khorassani

Keyword(s):

Ambient Temperature ◽

Tartaric Acid ◽

Aromatic Aldehydes ◽

One Pot ◽

Rate Determining Step ◽

State Approximation ◽

Solvent Free Conditions ◽

Steady State Approximation ◽

Absorbance Changes ◽

The One

Aim & Scope: The synthesis of highly substituted piperidine from the one-pot reaction between aromatic aldehydes, anilines and β-ketoesters in the presence of tartaric acid as a catalyst has been investigated in both methanol and ethanol media at ambient temperature. Different conditions of temperature and solvent were employed for calculating the thermodynamic parameters and obtaining an experimental approach to the kinetics and mechanism. Experiments were carried out under different temperature and solvent conditions. Material and Methods: Products were characterized by comparison of physical data with authentic samples and spectroscopic data (IR and NMR). Rate constants are presented as an average of several kinetic runs (at least 6-10) and are reproducible within ± 3%. The overall rate of reaction is followed by monitoring the absorbance changes of the products versus time on a Varian (Model Cary Bio- 300) UV-vis spectrophotometer with a 10 mm light-path cell. Results: The best result was achieved in the presence of 0.075 g (0.1 M) of catalyst and 5 mL methanol at ambient temperature. When the reaction was carried out under solvent-free conditions, the product was obtained in a moderate yield (25%). Methanol was optimized as a desirable solvent in the synthesis of piperidine, nevertheless, ethanol in a kinetic investigation had none effect on the enhancement of the reaction rate than methanol. Based on the spectral data, the overall order of the reaction followed the second order kinetics. The results showed that the first step of the reaction mechanism is a rate determining step. Conclusion: The use of tartaric acid has many advantages such as mild reaction conditions, simple and readily available precursors and inexpensive catalyst. The proposed mechanism was confirmed by experimental results and a steady state approximation.

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