Synthesis of new substituted dihydroheptalene derivatives: SiO2- and base-catalyzed rearrangement of dimethyl trans-3,8-dihydroheptalene-3,8-dicarboxylate

2001 ◽  
Vol 79 (1) ◽  
pp. 35-41
Author(s):  
Nurullah Saraçoglu ◽  
Abdullah Menzek ◽  
Armagan Kinal ◽  
Metin Balci
Keyword(s):  
Room Temperature ◽  
Heat Of Formation ◽  
Major Product ◽  
Similar Reaction ◽  
Am1 Calculations ◽  
Hydrogen Shift ◽  
Proton Shift ◽  
Major Isomer ◽  
Prolonged Reaction Time ◽  
Lower Heat

Dimethyl trans-3,8-dihydroheptalene-3,8-dicarboxylate (trans-3) isomerizes to dimethyl cis-3,8-dihydroheptalene-3,8-dicarboxylate (cis-3) upon treatment with SiO2. On the other hand, base-catalyzed reaction of trans-3 undergoes a direct 1,3-intramolecular proton shift to give 6 at room temperature in 5 min. Prolonged reaction time formed isomers 7 and 8 in a ratio of 4:1. AM1 calculations indicate that the isomer 8, which is formed as minor product, has a lower heat of formation (–99.34 kcal mol–1) than that of the major isomer 7 (–92.05 kcal mol–1). However, when a similar reaction was performed at 100°C, the thermodynamically more stable isomer 8 was formed as the major product. Furthermore, cycloaddition reactions of these new dihydroheptalene derivatives 6 and 7 with different dienophiles have been studied. The mechanism has been discussed.Key words: dihydroheptalene, cycloaddition, 1,3-hydrogen shift, cycloheptatriene–norcaradiene equilibrium.

scholarly journals Hetero-Diels–Alder reactions of hetaryl and aryl thioketones with acetylenic dienophiles

2015 ◽  
Vol 11 ◽  
pp. 576-582 ◽  
Author(s):  
Grzegorz Mlostoń ◽  
Paulina Grzelak ◽  
Maciej Mikina ◽  
Anthony Linden ◽  
Heinz Heimgartner
Keyword(s):  
High Pressure ◽  
Room Temperature ◽  
Thermal Conditions ◽  
Alder Reaction ◽  
Diels Alder ◽  
Hydrogen Shift ◽  
Diels Alder Reaction ◽  
Shift Sequence

Selected hetaryl and aryl thioketones react with acetylenecarboxylates under thermal conditions in the presence of LiClO4 or, alternatively, under high-pressure conditions (5 kbar) at room temperature yielding thiopyran derivatives. The hetero-Diels–Alder reaction occurs in a chemo- and regioselective manner. The initially formed [4 + 2] cycloadducts rearrange via a 1,3-hydrogen shift sequence to give the final products. The latter were smoothly oxidized by treatment with mCPBA to the corresponding sulfones.

scholarly journals Study of Spectroscopy and Thermodynamic Properties for Phoshours dioxide PO2 Molecular and Influence Study of Bond ( P-O ) on Spectroscopy Properties

2012 ◽  
Vol 9 (4) ◽  
pp. 616-622
Author(s):  
Baghdad Science Journal
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Room Temperature ◽  
Formation Enthalpy ◽  
Heat Of Formation ◽  
Vibration Modes ◽  
Equilibrium Distance ◽  
Atmosphere Pressure ◽  
Gibb’S Free Energy ◽  
Good Agreement

In This research a Spectroscopic complement and Thermodynamic properties for molecule PO2 were studied . That included a calculation of potential energy . From the curve of total energy for molecule at equilibrium distance , for bond (P-O), the degenerated of bond energy was (4.332eV) instate of the vibration modes of ( PO2 ) molecule and frequency that was found active in IR spectra because variable inpolarization and dipole moment for molecule. Also we calculate some thermodynamic parameters of ( PO2 ) such as heat of formation , enthalpy , heat Of capacity , entropy and gibb's free energy Were ( -54.16 kcal/mol , 2366.45 kcal/mol , 10.06 kcal /k/mol , 59.52 kcal /k /mol, -15370.51 kcal / mol ) respectively under condition of room temperature and atmosphere pressure ( 298 k , 1 atm.). We calculate there parameters at various temperature from ( 100 – 3000 ) K . It was found that the obtainded results were in a good agreement with previous experimental facts.

Cyclohexyneplatinum(0) Complexes Containing Di-t-butylphenylphosphine, t-butyldiphenylphosphine or Trimethylphosphine

1992 ◽  
Vol 45 (1) ◽  
pp. 135 ◽  
Author(s):  
MA Bennett ◽  
HG Fick ◽  
GF Warnock
Keyword(s):  
Pure State ◽  
Room Temperature ◽  
Main Product ◽  
Similar Reaction ◽  
Molar Proportion ◽  
Sodium Amalgam ◽  
Tertiary Phosphines

Cyclohexyneplatinum (0) complexes Pt(C6H8)L2 [L = PBut2Ph(4), PbutPh2(5)] analogous to the known complex (3) (L=PPh3) have been prepared by reaction of the two-coordinate complexes PtL2 with 1,2-dibromocyclohexene and 1% sodium amalgam. The corresponding tricyclohexylphosphine complex is formed by a similar reaction but it could not be isolated in a pure state. Attempts to prepare analogues of (4) and (5) containing cycloheptyne or cyclooctyne were unsuccessful, possibly because the bulky t-butyl groups of the tertiary phosphines hinder coordination of the larger rings. Bulky tertiary phosphines do not displace PPh3 from (3) but trimethylphosphine reacts with (3) to give successively Pt(C6H8)(PMe3)2(PPh3) (10) and Pt(C6H8)(PMe3)2 (11), as shown by 31P{1H) n.m.r. spectroscopy. The tertiary phosphines in these complexes equilibrate rapidly at room temperature in benzene and only (10) can be isolated as a solid from the reaction. Complexes (4) and (5) react with HCl (1 molar proportion) to give n1-cyclohexen-l-yl complexes trans- PtCl (C6H9)L2 [L= PBut2Ph(6), PButPh2 (7)]. In the absence of air, (4) reacts with methanol at 65°C to give the hydrido complex trans- PtH (C6H9)(PBut2Ph)2 (8). In the presence of oxygen from the air, however, the main product is the dioxygen complex Pt(O2)(Pbut2Ph)2 (9). This represents an unusual example of complete displacement of cyclohexyne from a platinum(0) complex by a π-acceptor ligand.

Photolysis of Thiolane Vapor

1971 ◽  
Vol 49 (8) ◽  
pp. 1316-1320 ◽  
Author(s):  
Silvia Braslavsky ◽  
Julian Heicklen
Keyword(s):  
Quantum Yield ◽  
Excited States ◽  
Room Temperature ◽  
Major Product ◽  
Unstable Product

The photolysis of thiolane vapor [Formula: see text] was studied at room temperature with 2139 Å radiation. The major product was C2H4, whose quantum yield decreased as the pressure was increased. Next in importance were 1-C4H8, C3H6, and C2H6. Also produced were CH4, c-C3H6, 1,3-C4H6, CH2CHSH, [Formula: see text], 1-C4H9SH, H2, C3H8, n-C4H10, c-C4H8, polymer, and an unstable product tentatively identified as 1-butene-1-thiol. All products were initial products of the reaction. Experiments with added C3H6 showed the absence of sulfur atoms. The results are interpreted in terms of two excited states and an intermediate which might be the diradical •CH2CH2CH2CH2S•.

A Potential New RAFT - Click Reaction or a Cautionary Note on the Use of Diazomethane to Methylate RAFT-synthesized Polymers

2011 ◽  
Vol 64 (4) ◽  
pp. 433 ◽  
Author(s):  
Ming Chen ◽  
Graeme Moad ◽  
Ezio Rizzardo
Keyword(s):  
Molecular Weight ◽  
Methyl Methacrylate ◽  
Room Temperature ◽  
Click Reaction ◽  
Raft Polymerization ◽  
Dipolar Cycloaddition ◽  
Low Molecular Weight ◽  
Similar Reaction ◽  
Poly Methyl Methacrylate ◽  
End Groups

It has been found that diazomethane undergoes a facile 1,3‐dipolar cycloaddition with both dithiobenzoate RAFT agents and the dithiobenzoate end‐groups of polymers formed by RAFT polymerization. Thus, 2‐cyanoprop‐2‐yl dithiobenzoate on treatment with diazomethane at room temperature provided a mixture of stereoisomeric 1,3‐dithiolanes in near quantitative (>95%) yield. A low‐molecular‐weight RAFT‐synthesized poly(methyl methacrylate) with dithiobenzoate end‐groups underwent similar reaction as indicated by immediate decolourization and a quantitative doubling of molecular weight. Higher‐molecular‐weight poly(methyl methacrylate)s were also rapidly decolourized by diazomethane and provided a product with a bimodal molecular weight distribution. Under similar conditions, the trithiocarbonate group does not react with diazomethane.

THE PHOTO-OXIDATION OF AZOMETHANE

1955 ◽  
Vol 33 (3) ◽  
pp. 496-506 ◽  
Author(s):  
G. R. Hoey ◽  
K. O. Kutschke
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Room Temperature ◽  
Major Product ◽  
Steric Factor ◽  
Primary Process ◽  
Methyl Radicals ◽  
Low Oxygen ◽  
Secondary Product ◽  
Photo Oxidation

The photo-oxidation of azomethane has been studied at low oxygen pressures (0.02 to 1 mm.) in the temperature range ca. 25 °C. to 161 °C. The primary process in the normal photolysis of azomethane is essentially unaffected by the presence of oxygen. Carbon monoxide is probably a secondary product of the oxidation of methyl radicals. Carbon dioxide formation is quite small, and therefore neither methyl radicals nor CH3N=N—CH2 radicals are oxidized appreciably to carbon dioxide. Nitrous oxide, which is a major product of the oxidation, is most likely formed from the oxidation of CH3N=NCH2 radicals. The suggested mechanism of N2O formation is:[Formula: see text] The reaction of methyl radicals with oxygen was found to proceed with a negligible activation energy and a steric factor of the order of 10−2. Evidence for the occurrence of the reactions[Formula: see text]at room temperature was obtained.

New 1,3-dihydroazepin-2-one derivatives by [3,3]-sigmatropic rearrangement of suitably substituted 2-alkenylcyclopropyl isocyanates

2004 ◽  
Vol 82 (2) ◽  
pp. 166-176 ◽  
Author(s):  
Hans-Ulrich Reissig ◽  
Gesine Böttcher ◽  
Reinhold Zimmer
Keyword(s):  
Sigmatropic Rearrangement ◽  
Similar Reaction ◽  
Model Compounds ◽  
Double Bond Migration ◽  
Proton Shift ◽  
Sigmatropic Rearrangements ◽  
Primary Products ◽  
Curtius Reaction ◽  
Reaction Barriers ◽  
Final Proton

The 2-siloxysubstituted 2-alkenylcyclopropanecarboxylic acids 10–14 were converted into the corresponding carbonyl azides by treatment with DPPA (diphenyl phosphorazidate) and triethylamine. On heating to 80 °C these intermediates smoothly furnished azepinone derivatives 19–25 in moderate to good overall yields, which are the result of a sequence of Curtius reaction to cyclopropylisocyanates, [3,3]-sigmatropic rearrangement, and a final proton shift. The primary products may undergo desilylation (to afford azepin-2,5-diones such as 23) or double bond migration (to compound 25). Cyclopropanecarboxylic acids cis-32, cis-34, and cis-35, which bear no 2-siloxy group, similarly provided azepinone derivatives 36–38 in good yields. No influence of the 2-siloxy substituent on the reaction course and rates could be observed in these qualitative studies, which was confirmed by DFT calculations with model compounds 39–42 showing similar reaction barriers for rearrangements of cyclopropylisocyanates with or without a 2-hydroxy group.Key words: vinyl cyclopropanes, carbonylazides, [3.3]-sigmatropic rearrangements, azepinones.

scholarly journals Coordination-driven self-assembly of discrete Ru6–Pt6 prismatic cages

2018 ◽  
Vol 14 ◽  
pp. 2242-2249 ◽  
Author(s):  
Aderonke Ajibola Adeyemo ◽  
Partha Sarathi Mukherjee
Keyword(s):  
Mass Spectrometry ◽  
Self Assembly ◽  
Room Temperature ◽  
Geometry Optimization ◽  
Platinum Metal ◽  
Major Product ◽  
Spectroscopic Techniques ◽  
One Pot ◽  
Infrared Studies ◽  
Trigonal Prismatic

The coordination-driven self-assembly of two new Ru6–Pt6 hexanuclear trigonal prismatic cages comprising arene–ruthenium(II) clips (1a(NO 3 ) 2 and 1b(NO 3 ) 2 ) and a tritopic platinum(II) metalloligand 2 has been performed in methanol at room temperature. The [3 + 2] hexanuclear cages 3a and 3b were isolated in good yields and characterized by well-known spectroscopic techniques including multinuclear NMR, mass spectrometry, UV–vis and infrared studies. Geometry optimization revealed the shapes and sizes of these hexanuclear prismatic cages. The combination of ruthenium and platinum metal center in a one-pot self-assembly reaction showcases the construction of aesthetically elegant heterometallic structures in supramolecular chemistry leading to the formation of a single major product.

Confirmation of Pesticide Residues Identity. X. Mirex

1978 ◽  
Vol 61 (6) ◽  
pp. 1475-1480
Author(s):  
Alfred S Y Chau ◽  
John M Carron ◽  
Hung Tse
Keyword(s):  
Retention Time ◽  
Reductive Dechlorination ◽  
Pesticide Residues ◽  
Room Temperature ◽  
Major Product ◽  
Chromatographic Retention ◽  
Liquid Chromatographic ◽  
Chromous Chloride

Abstract Three procedures using 3 different ratios of chromous chloride and acetone at room temperature or 55–60°C are described for confirming the presence of Mirex (dodecachlorooctahydro- l,3,4-metheno-2H-cyclobuta [cd] pentalene). Each procedure gives a different major product with a different gas-liquid chromatographic retention time. The factors that could affect this reductive dechlorination were also studied. The procedures can detect, respectively, 1.1, 0.7, and 0.5 times the amount of the Mirex standard (taken as 1.0) used in the investigation.

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