scholarly journals Kinetic Separation of cis-and trans-Limonene Epoxide: Reaction of Diastereomeric Mixture of Limonene Oxides with Secondary Amine and Carbamate

2021 ◽  
Vol 33 (11) ◽  
pp. 2667-2670
Author(s):  
M.M. El Hammoumi ◽  
L. Ait Said ◽  
A. El Bachiri ◽  
M. Khoukhi
Keyword(s):  
Trans Isomer ◽  
Secondary Amine ◽  
Ethyl Carbamate ◽  
Epoxide Ring ◽  
Diastereomeric Mixture ◽  
Limonene Oxide ◽  
Cis And Trans ◽  
Hydrolysis Of ◽  
Diastereomeric Purity ◽  
Kinetic Separation

A simple kinetic separation of (1:1) diastereomeric mixture of limonene oxides was used to purify cis-and trans-diastereomers of (R)-(+)-limonene oxide. The epoxide ring of trans-isomer was selectively opened by (R)-N-methyl-(α-methyl-benzyl)amine. This secondary nucleophilic amine left cis-limonene oxide largely unreacted and was obtained up to 90% yield. In a diverse way, (R)-N-(α-methylbenzyl) ethyl carbamate, selectively catalyze hydrolysis of cis-limonene oxide to 1,2-limonene diol leaving trans-limonene oxide largely unreacted. The unreacted trans-limonene oxide was recovered in up to 75% yield. HPLC and NMR analyses were used to demonstrate that the isolation of cis-and trans-diastereomers of (R)-(+)-limonene oxide has shown that > 98% were pure. As a result, depending on the realization of the secondary amine or carbamate in the presence of water, either cis-or trans-limonene oxide may be obtained in high diastereomeric purity.

Heteropoly acid catalysis for the isomerization of biomass-derived limonene oxide and kinetic separation of the trans-isomer in green solvents

2019 ◽  
Vol 584 ◽  
pp. 117173 ◽  
Author(s):  
Rafaela F. Cotta ◽  
Rafael A. Martins ◽  
Matheus M. Pereira ◽  
Kelly A. da Silva Rocha ◽  
Elena F. Kozhevnikova ◽  
...  
Keyword(s):  
Trans Isomer ◽  
Heteropoly Acid ◽  
Acid Catalysis ◽  
Green Solvents ◽  
Limonene Oxide ◽  
Kinetic Separation

Vinyl ether hydrolysis. XXIX. 1-Methoxy-1,3-butadiene: reaction mechanism and implication for hydrolysis of the mutagen fecapentaene-12

1994 ◽  
Vol 72 (7) ◽  
pp. 1632-1636 ◽  
Author(s):  
Yvonne Chiang ◽  
Robert Eliason ◽  
Gary H.-X. Guo ◽  
A. Jerry Kresge
Keyword(s):  
Vinyl Ether ◽  
Trans Isomer ◽  
Acid Catalysis ◽  
Isotope Effects ◽  
Hydronium Ion ◽  
Rapid Formation ◽  
Methyl Vinyl Ether ◽  
Cis And Trans ◽  
Hydrolysis Of ◽  
Cis Isomer

The hydrolysis of cis- and trans-1-methoxy-1,3-butadiene in aqueous solution occurs by hydron transfer to the δ-carbon atom with little or no β-hydronation to give crotonaldehyde as essentially the sole aldehyde product. The reaction gives appreciable hydronium-ion isotope effects in the normal direction [Formula: see text] and shows general acid catalysis; five carboxylic acid catalytic coefficients for hydrolysis of the trans isomer give a good Brønsted relation with the exponent α = 0.59. This is taken as evidence that these reactions occur by the conventional mechanism for vinyl ether hydrolysis involving rate-determining hydron transfer to substrate carbon followed by rapid formation and decomposition of a hemiacetal intermediate. Comparison of the reactivity of the present dienyl ethers with that of their monoenyl analog, methyl vinyl ether, shows that introduction of the second double bond decreases reactivity considerably: the hydronium-ion catalytic coefficient is reduced by a factor of 8.3 for the trans isomer and by a factor of 160 for the cis isomer. This reduction supports a hypothesis advanced to explain the occurrence of reaction by a different mechanism recently discovered in the hydrolysis of the strongly mutagenic polyenyl ether, fecapentaene-12.

The hydrolysis of substituted cyclopropyl bromides in water. IV. The effect of vinyl and methyl substitution on ΔCP≠

1977 ◽  
Vol 55 (13) ◽  
pp. 2582-2588 ◽  
Author(s):  
Surendra Singh ◽  
Ross Elmore Robertson
Keyword(s):  
Transition State ◽  
Trans Isomer ◽  
Charge Separation ◽  
Methyl Substitution ◽  
A Value ◽  
Low Degree ◽  
Cis And Trans ◽  
Hydrolysis Of ◽  
Limiting Values

In this study of the effect of vinyl and methyl substitution on the rates of hydrolysis of cyclopropyl bromides in water, we examine the changes in ΔCP≠ with substitution and configuration. The unusual values of ΔCP≠ found by Ong and Robertson (Can. J. Chem. 52, 2660 (1974)) for the hydrolysis of 2-cis- and trans-vinylcyclopropyl bromide are shown to be characteristic of the vinyl substituent and reflect either a transition state which corresponds to a low degree of charge separation or to internal cancellation due to the formation of an extended dienylic cation. The 2,3-cis,cis-dimethylcyclopropyl bromide gave a value of ΔCP≠ = −145 cal mol−1 deg−1, comparable to limiting values obtained for hydrolysis of 1- and 2-adamantyl nitrate. The corresponding value of ΔCP≠ for 2,3-cis,trans-dimethylcyclopropyl bromide (−56 cal mol−1 deg−1) was less negative than for the 2,3-trans,trans isomer (−75 cal mol−1 deg−1). The mechanistic implications are discussed.

Unveiling the coexistence of cis- and trans-isomers in the hydrolysis of ZrO2: A coupled DFT and high-resolution photoelectron spectroscopy study

2020 ◽  
Vol 153 (24) ◽  
pp. 244308
Author(s):  
Ali Abou Taka ◽  
Mark C. Babin ◽  
Xianghai Sheng ◽  
Jessalyn A. DeVine ◽  
Daniel M. Neumark ◽  
...  
Keyword(s):  
High Resolution ◽  
Photoelectron Spectroscopy ◽  
Spectroscopy Study ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Hydrolysis Of

scholarly journals Reaction of cis- and trans-Dichlorotetra(Dimethylsulfoxide)Ruthenium(II) With the Antiviral Drug Acyclovir

2000 ◽  
Vol 7 (6) ◽  
pp. 325-334 ◽  
Author(s):  
Aglaia Koutsodimou ◽  
Giovanni Natile
Keyword(s):  
Trans Isomer ◽  
Early Stage ◽  
Antiviral Drug ◽  
Metallic Substrate ◽  
Purine Base ◽  
Coordination Environment ◽  
Molar Ratios ◽  
Discrete Amount ◽  
Cis And Trans ◽  
Cis Isomer

NMR was used to investigate the reaction of cis- and trans-[RuCl2(DMSO)4] with the antiviral drug acyclovir, a guanine derivative containing the acyclic (2-hydroxo) ethoxymethyl pendant linked to N(9). Studies were performed in aqueous solutions at ambient temperature and at 37 °C, and at various molar ratios. Both isomers yielded two compounds, a monoadduct and a bisadduct, the relative yields being dependent upon the metal to ligand concentration ratios. The products derived from the two Ru isomers displayed identical NMR spectra, suggesting that they have the same coordination environment, however the rate of formation of the monoadduct was higher in the case of the trans isomer than in the case of the cis isomer, while the rate of conversion of the monoadduct into the bisadduct appeared to be similar in both cases. As a consequence in the case of the trans isomer there is accumulation of monoadduct in the early stage of the reaction, whose concentration afterwards decreases with the progress of the reaction. As for platinum, also for ruthenium the preferred binding site is N(7) of the purine base, however, in the case of ruthenium a discrete amount of bisadduct is formed even in the presence of an excess of metallic substrate with respect to the acyclovir ligand; under similar conditions a platinum substrate would have given, nearly exclusively, the monoadduct.

ESSENTIAL OILS AND THEIR CONSTITUENTS: XXVII. COMPOSITION OF OIL OF GINGERGRASS

1965 ◽  
Vol 43 (2) ◽  
pp. 521-525 ◽  
Author(s):  
M. C. Nigam ◽  
Ishwar C. Nigam ◽  
Leo Levi
Keyword(s):  
Essential Oil ◽  
Essential Oils ◽  
Aromatic Compound ◽  
Limonene Oxide ◽  
Cis And Trans

Oil of gingergrass was found to contain the following as yet unreported constituents: trans-p-menthene-8-diol-1,2; cis- and trans-carveol; cis- and trans-dihydrocarvone; piperitenone and limonene oxide. The presence of an aromatic compound for which gas chromatographic and infrared criteria of identity were determined was also demonstrated. Limonene oxide is probably the most important precursor of these and related monoterpenoids of the essential oil.

Structure et réactivité. IV. Diastéréosélectivité de la réduction de cétones par le borohydrure de sodium. De l'influence de l'effet de champs de substituants polaires éloignés

1979 ◽  
Vol 57 (21) ◽  
pp. 2823-2826 ◽  
Author(s):  
Jean-Pierre Aycard ◽  
Ronald Lafrance ◽  
Bernard Boyer
Keyword(s):  
Trans Isomer ◽  
Cyano Group ◽  
Specific Effect ◽  
Group Effect ◽  
Stable Isomer ◽  
Free Enthalpy ◽  
Steric Strain ◽  
Experimental Values ◽  
Cis And Trans

The cyano group effect on diastereoselectivity is studied through the reduction of cis and trans 3-R 4-cyano cyclohexanones with NaBH4; the diastereoselectivity (zero for R = H) is 74 and 62% respectively (R = CH3) and 74 and 50% (R = (CH3)3C), the more stable isomer being always the major one. These stereoselectivities are rationalized from the experimental values of free enthalpy between conformers and from the diastereoselectivities of the 3-t-butyl (and 4-t-butyl) cyclohexanones, cis 3,5-dimethyl and 3,3,5-trimethyl cyclohexanones, without taking account of a cyano group specific effect. The decrease in diastereoselectivity for R = (CH3)3C (trans isomer) is associated with deformation induced by steric strain between the substituents.

[1H,15N] N.M.R. Kinetic Studies of Reactions of cis- and trans-[PtCl2(15NH3)(c-C6H1115NH2)] with Guanosine 5'-Monophosphate

1999 ◽  
Vol 52 (3) ◽  
pp. 173 ◽  
Author(s):  
Sarah J. Barton ◽  
Kevin J. Barnham ◽  
Abraha Habtemariam ◽  
Urban Frey ◽  
Rodney E. Sue ◽  
...  
Keyword(s):  
Trans Isomer ◽  
Active Metabolite ◽  
Kinetic Studies ◽  
Trans Influence ◽  
Trans Complex ◽  
Kinetics Of Reaction ◽  
Cis And Trans ◽  
Kinetics Of ◽  
Cis Isomer ◽  
Amine Ligand

cis-[PtCl2(15NH3)(c-C6H11NH2)] is an active metabolite of the oral platinum(IV) anticancer drug cis,trans,cis-[PtCl2(CH3CO2)2(NH2)(c-C6H11NH2)]. Since it is likely that guanine bases on DNA are targets for this drug, we have analysed the kinetics of reaction of this platinum(II) metabolite with guanosine 5′-monophosphate (5′-GMP) at 310 K, pH 7, using [1H, 15N] n.m.r. methods. Reactions of the trans isomer are reported for comparison. The reactions proceed via aquated intermediates, and, for the cis isomer, the rates of aquation and substitution of H2O by 5′-GMP are 2-5 times faster trans to the amine ligand (c-C6H11NH2) compared to trans to NH3 for both the first and second steps. For the trans complex, the first aquation step is c. 3 times faster than for the cis complex, as expected from the higher trans influence of Cl¯, whereas the rate of the second aquation step (trans to N7 of 5′-GMP) is comparable to that trans to NH3. These findings have implications for the courses of reactions with DNA.

Some investigations of the chemistry of tellurium chloride pentafluoride, its reaction with caesium fluoride, and the preparation of cis and trans methoxytellurium(VI) chloride tetrafluoride, (CH3O)TeClF4

1984 ◽  
Vol 62 (8) ◽  
pp. 1477-1482 ◽  
Author(s):  
Lawrence J. Lawlor ◽  
Jack Passmore
Keyword(s):  
Vibrational Spectrum ◽  
Trans Isomer ◽  
Room Temperature ◽  
Temperature Range ◽  
Cis And Trans

The reaction of TeClF5 with CH3OH, and CH3OSiMe3, leads to a mixture of cis- and trans-(CH3O)TeClF4 in a ratio of 1:6, as well as some unidentified Te(IV) product. The vibrational spectrum of the 1:6 mixture of cis- and trans-(CH3O)TeClF4 was accounted for on the basis of the predominant pseudo-C4vtrans isomer. TeClF5 is unreactive towards anhydrous HF, SbF5, AlCl3, SO2, F2, and ClF at room temperature. Over the temperature range 70–250 °C it thermally decomposes to TeF6, TeF4, and Cl2. It slowly reacts with CsF to form CsTeF5, TeF6, Cl2, and small amounts of ClF, and with HNMe2 it is also reduced to form TeF4•HNMe2.

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