A Stereochemical and Kinetic Study of the Conversion of Methyl Cyclopropyl Ketones to 4,5-Dihydrofurans

1973 ◽  
Vol 51 (10) ◽  
pp. 1487-1493 ◽  
Author(s):  
Donald Edward McGreer ◽  
James William McKinley
Keyword(s):  
Kinetic Study ◽  
Ring Opening ◽  
Photochemical Reactions ◽  
Order Reaction ◽  
Ring Closure ◽  
Hydrogen Shift ◽  
First Order ◽  
Bond Rotation ◽  
Cyclopropyl Ketones ◽  
Cis And Trans

The thermal and photochemical conversion of (1R*,2R*,3S*), (1S*,2R*,3S*), and (1S*,2R*,3R*)-1-acetyl-1,2-dimethyl-3-phenylcyclopropane (1, 2, and 3) to cis- and trans-2,3,4-trimethyl-5-phenyl-4,5-dihydrofurans has been studied. Concurrent with this reaction is an equilibration of 1, 2, and 3, a thermal ring opening of 1 by a 1,5-hydrogen shift, and a cyclopropane-to-propene type reaction under the photochemical conditions. The dihydrofuran from 1 and 2 by the thermal and photochemical conditions is 97% trans- and 3% cis- corresponding to predominant retention at the migrating carbon. The dihydrofuran formed from 3 by the thermal and photochemical reaction is 85% cis- and 15% trans- again corresponding to predominant retention. A kinetic study of the rearrangement of 1-acetyl-1-methyl-2-phenylcyclopropane to 1,2-dimethyl-5-phenyl-4,5-dihydrofuran provides Ea of 48.1 kcal/mol and log A of 14.9 for this first order reaction in the temperature range of 255–288 °C.It is concluded that the thermal and photochemical reactions occur by a non-concerted process through a common 1,3-diradical intermediate in which bond rotation and ring closure steps are competitive.

Thermal intramolecular reactions of Δ1-1,2,4-triazolines with extended exocyclic unsaturation

1988 ◽  
Vol 66 (3) ◽  
pp. 385-390 ◽  
Author(s):  
Adrian L. Schwan ◽  
John Warkentin
Keyword(s):  
Ring Opening ◽  
Hydrolysis Product ◽  
Sigmatropic Rearrangement ◽  
Membered Ring ◽  
Ring Closure ◽  
Experimental Results ◽  
First Order ◽  
Ring Opening Reaction ◽  
Intramolecular Reactions

Fumaratotriazoline (1) and amidotriazoline (3) undergo thermal first-order transformations in solution at 65 °C. The former affords the isomeric pyrrole 5 and its hydrolysis product 6. A mechanism involving opening of the initial five-membered ring to form 8, followed by closure to a new five-membered ring (9), is proposed. Amidotriazoline (3) loses N2 on heating to form 19. The experimental results are best accommodated in terms of a novel mechanism involving an electrocyclic ring closure, a [3 + 2] cycloreversion to form an ylide, a sigmatropic rearrangement of the ylide, and, finally, an electrocyclic ring-opening reaction.

The formation of O2(a1Δg) in homogeneous and heterogeneous atom recombination

1986 ◽  
Vol 64 (12) ◽  
pp. 1614-1620 ◽  
Author(s):  
A. A. Ali ◽  
E. A. Ogryzlo ◽  
Y. Q. Shen ◽  
P. T. Wassell
Keyword(s):  
Kinetic Study ◽  
Gas Phase ◽  
Molecular Oxygen ◽  
Rate Constant ◽  
Room Temperature ◽  
High Efficiency ◽  
Flow System ◽  
Order Reaction ◽  
Third Order ◽  
First Order

The recombination of oxygen atoms has been studied in a discharge flow system at room temperature. The yield of O2(a1Δg) in the recombination on Pyrex has been found to be 0.08 (±0.02). In the gas phase, O2(a) was found to be formed in a process that is second order in [O] and first order in [N2]. The rate constant for this third-order reaction was found to be 3.4 (±0.4) × 10−34 cm6∙molecule−2∙s−1, representing a yield of 0.07 (±0.02). In the presence of molecular oxygen, the rate of production of O2(a) was found to increase. A kinetic study of this effect led to the conclusion that collisions of molecular oxygen with an unidentified precursor can produce O2(a) with high efficiency.

scholarly journals Stereoselective Synthesis and Antiproliferative Activity of Steviol-Based Diterpen Aminodiols

2019 ◽  
Vol 21 (1) ◽  
pp. 184
Author(s):  
Dániel Ozsvár ◽  
Viktória Nagy ◽  
István Zupkó ◽  
Zsolt Szakonyi
Keyword(s):  
Antiproliferative Activity ◽  
Ring Opening ◽  
Stereoselective Synthesis ◽  
Click Reaction ◽  
Substituent Effects ◽  
Ring Closure ◽  
Secondary Amines ◽  
Structure Activity ◽  
Cis And Trans ◽  
Benzyl Substituent

A library of steviol-based trifunctional chiral ligands was developed from commercially available natural stevisoide and applied as chiral catalysts in the addition of diethylzinc to benzaldehyde. The key intermediate steviol methyl ester was prepared according to literature procedure. Depending on the epoxidation process, both cis- and trans-epoxyalcohols were obtained. Subsequent oxirane ring opening with primary and secondary amines afforded 3-amino-1,2-diols. The ring opening with sodium azide followed by a “click” reaction with alkynes resulted in dihydroxytriazoles. The regioselective ring closure of N-substituted aminodiols with formaldehyde was also investigated. The resulting steviol-type aminodiols were tested against a panel of human adherent cancer cell lines (A2780, SiHa, HeLa, and MDA-MB-231). It was consistently found that the N-benzyl substituent is an essential part within the molecule and the ring closure towards N-benzyl substituted oxazolidine ring system increased the antiproliferative activity to a level comparable with that of cisplatine. In addition, structure–activity relationships were examined by assessing substituent effects on the aminodiol systems.

scholarly journals Permanganatic oxidation of neomycine sulphate salt in basic media: a kinetic study

2019 ◽  
Vol 9 (1) ◽  
pp. 159-164
Author(s):  
Narayan V. Lawale ◽  
Bhagwan Singh Dobhal ◽  
Sandip Singh Gaur ◽  
Rajendra Pardeshi
Keyword(s):  
Kinetic Study ◽  
Order Reaction ◽  
First Order Reaction ◽  
Pseudo First Order Reaction ◽  
Reaction Conditions ◽  
First Order ◽  
Alkaline Permanganate ◽  
Different Temperatures ◽  
Alkaline Conditions ◽  
Pseudo First Order

Permanganatic oxidation of Neomycine sulphate salt has been studied at different temperatures using spectrophotometer under alkaline conditions. The effect of variation of substrate Neomycine sulphate salt (NS), oxidant (KMnO4) and NaOH was studied under pseudo first order reaction conditions. The effect of different salts and solvents on oxidation of NS was also studied. The reaction was found to be first order with respect to oxidant, substrate and NaOH.. Keywords: Neomycine sulphate salt (NS), KMnO4 , permanganatic  oxidation, alkaline permanganate

Kinetic Study of Light Mercaptans in the Presence of Merox Catalyst and Caustic Soda

2013 ◽  
Vol 11 (1) ◽  
pp. 431-442 ◽  
Author(s):  
Mohammad Reza Ehsani ◽  
Peyman Mirjani ◽  
Alireza Safadoost
Keyword(s):  
Caustic Soda ◽  
Kinetic Study ◽  
Oxidation Rate ◽  
Order Reaction ◽  
First Order Reaction ◽  
Kinetic Investigation ◽  
First Order ◽  
Oxidation Rates

Abstract Due to the disgusting smell of light mercaptans, researchers are not interested in working with them, so there is not enough information available on their kinetics. This work presents kinetic investigation of oxidation of ethyl, normal-propyl, iso-propyl, and iso-butyl mercaptans in the presence of Merox catalyst. The results demonstrated that the oxidation rates of all mercaptans were first-order reaction with respect to mercaptan concentration, and the increase in NaOH concentration reduced the oxidation rate. While it was observed that there was a similarity between oxidation pattern of iso-propyl and ethyl mercaptans, another similarity was discovered between normal-propyl and iso-butyl mercaptans.

Synthesis and Properties of 1-(3,5-dimethyl-4-isoxazole)-2-(2-methyl-(5-ethynyl)-3-thienyl)perfluorocyclopentene

2014 ◽  
Vol 1078 ◽  
pp. 82-85
Author(s):  
Mei Li Cai ◽  
Zhao Yan Tian ◽  
Shi Qiang Cui ◽  
Shou Zhi Pu
Keyword(s):  
Response Time ◽  
Ring Opening ◽  
Color Change ◽  
Uv Light ◽  
Order Reaction ◽  
First Order Reaction ◽  
Fluorescence Properties ◽  
First Order ◽  
Ring Opening Reaction ◽  
Hexane Solution

A new photochromic diarylethene of 1-(3,5-dimethyl-4-isoxazole)-2- (2-methyl-(5-ethynyl)-3-thienyl) perfluorocyclopentene (1o) was synthesized. Its photochromic and fluorescence properties were investigated systematically. Upon irradiation with UV light with the extended response time, the diarylethene underwent a ring opening reaction to produce closed forms and color change in solution. The results showed the compound exhibited good photochromism in hexane solution. The kinetic experiments showed that the cyclization and cycloreversion processes were zeroth and first order reaction, respectively. Moreover, diarylethene1oalso exhibited obviously fluorescence switches along with the photochromism.

Rapid racemization of an optically active cyclopropene derivative via ring opening, bond rotation, and ring closure

1972 ◽  
Vol 94 (8) ◽  
pp. 2882-2883 ◽  
Author(s):  
Eunice J. York ◽  
Wolfgang Dittmar ◽  
J. Ronald Stevenson ◽  
Robert G. Bergman
Keyword(s):  
Ring Opening ◽  
Optically Active ◽  
Ring Closure ◽  
Bond Rotation

Synthesis and Properties of [1-(3,5-dimethyl-4-iodoisoxazole)-2-(2-methyl-(5-ethynyl)trimethylsilane-3-thienyl)perfluorocyclopentene

2014 ◽  
Vol 707 ◽  
pp. 44-47
Author(s):  
Zhao Yan Tian ◽  
Shi Qiang Cui ◽  
Shou Zhi Pu
Keyword(s):  
Response Time ◽  
Ring Opening ◽  
Color Change ◽  
Uv Light ◽  
Order Reaction ◽  
Acetonitrile Solution ◽  
Fluorescent Properties ◽  
Photochromic Behavior ◽  
First Order ◽  
Ring Opening Reaction

A photochromic diarylethene of [1-(3,5-dimethyl-4-iodoisoxazole)-2-(2-methyl-(5-ethynyl) trimethylsilane-3-thienyl) perfluorocyclopentene (1o) was synthesized and characterized. Its properties, including photochromic behavior and fluorescent properties have been investigated. Upon irradiation with UV light with the extended response time, the diarylethene underwent a ring opening reaction to produce closed forms and color change in solution. The results showed the compound exhibited good photochromism in acetonitrile solution. The kinetic experiments showed that the cyclization and cycloreversion processes were zeroth and first order reaction, respectively. Moreover, diarylethene1oalso exhibited obviously fluorescence switches along with the photochromism.

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