Intramolecular Homolytic Displacement. XXIII. Selectivity in the Induced Decomposition of Ethyl t-Butylperoxymethylpropenoate by Radicals Formed From Methyl Propanoate and Derivatives

1995 ◽  
Vol 48 (2) ◽  
pp. 233 ◽  
Author(s):  
M Degueilcastaing ◽  
C Navarro ◽  
F Ramon ◽  
B Maillard
Keyword(s):  
Thermal Decomposition ◽  
Double Bond ◽  
Iodine Atom ◽  
Hydrogen Abstraction ◽  
Alkyl Iodide ◽  
Alkyl Radicals ◽  
Tributyltin Hydride ◽  
Induced Decomposition ◽  
Derivatives Of ◽  
Methyl Propanoate

Thermal decomposition of t-butyl peracetate in a solution of ethyl t- butylperoxymethylpropenoate in methyl propanoate led to the products of substitution of the three different hydrogens in the molecule of the methyl ester by the 2,3-epoxy-2-ethoxycarbonylpropyl group. An SHi reaction on the peroxide function, following the addition to the double bond, is responsible for the formation of these epoxides . Such a result is due to the low regioselectivity of the hydrogen abstraction from methyl propanoate by t- butoxyl radicals, and no improvement could be obtained by changing the relative ratios of the reactants, in converse to previous results described for similar reactions. Thus, selective creation of alkyl radicals was developed through the generation of tributylstannyl radicals as mediator radicals, by reaction of t- butoxyl radicals on tributyltin hydride or hexabutylditin ; the mediator radicals abstract an iodine atom from the alkyl iodide. Application of this methodology to the three iodo derivatives of methyl propanoate permitted us to obtain selectively each of the three epoxides.

Investigations on the thermal decomposition of olefins

1962 ◽  
Vol 265 (1323) ◽  
pp. 519-537 ◽  
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Double Bond ◽  
Carbon Atom ◽  
Chromatographic Analysis ◽  
Indirect Method ◽  
Hydrogen Abstraction ◽  
Reaction Products ◽  
A Value ◽  
Order Of Magnitude

It has been shown that at 530 °C there is practically no decomposition of olefins not possessing b C—C bond β to the double bond. The rate constants for the decomposition of various olefins at 530 °C over the range of p 0 from 25 to 300 mm have been measured. The relative rates of decomposition and polymerization of ethylene at 530, 600 and 630 °C have been studied. On the basis of chromatographic analysis of the reaction products both in the presence and in the absence of nitric oxide it is concluded that the ethane formed comes mainly from the secondary decomposition of polymers. At 530 °C the inhibitory activity of nitric oxide is exerted only on some olefins and even then it is rather small. All olefins are, however, subject to a remarkable stimulatory activity of nitric oxide. Over the range of pressures investigated this accelerating effect on the decomposition depends linearly on the olefin and nitric oxide pressures r 0 = k 0 [RK] + k 2 [RH] [NO]. The values of the constants for different olefins have been determined. The order of magnitude of the constant k 2 was found to be the same for all olefins investigated except ethylene and propylene, the values lying between 1.0 x 10 -4 and 3.0 x 10 -4 min -1 (mm NO) -1 . Propylene, which possesses an unusually small number (3) of weak C—H bonds and only primary ones, gave (by an indirect method) the lower value (2 ± 1) x 10 -6 min -1 (mm NO) -1 . Ethylene, the only olefin without weak C—H bonds, gave (by an indirect method), a value of k 2 of about (4 ± 1) x 10 -6 min -1 (mm NO) -1 . The reaction of hydrogen abstraction from the olefin molecule by nitric oxide is assumed responsible for the stimulatory phenomenon. The low value of k 2 for ethylene compared with the values for other olefins and for paraffins can be explained as a result of the strengthening influence of the double bond on the C—H bond with the doubly bound carbon atom. The different roles of the inhibitory and accelerative functions of nitric oxide in the decomposition of paraffins and olefins are considered to be mainly responsible for the changes in the shape of the ∆p –time curves as P NO is varied. On this basis the phenomenon of the apparently transistory activity of nitric oxide as an inhibitor in some cases can be explained.

Thermal decomposition of some derivatives of 1,3-dinitro-1,3-diaza-5,7-dioxacyclooctane

2006 ◽  
Vol 76 (10) ◽  
pp. 1632-1633
Author(s):  
R. S. Stepanov ◽  
L. A. Kruglyakova ◽  
A. M. Astakhov
Keyword(s):  
Thermal Decomposition ◽  
Derivatives Of

scholarly journals Oxepinamide F biosynthesis involves enzymatic d-aminoacyl epimerization, 3H-oxepin formation, and hydroxylation induced double bond migration

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Liujuan Zheng ◽  
Haowen Wang ◽  
Aili Fan ◽  
Shu-Ming Li
Keyword(s):  
Cytochrome P450 ◽  
Double Bond ◽  
Biosynthetic Pathway ◽  
Hydroxyl Group ◽  
Cytochrome P450 Enzyme ◽  
Double Bond Migration ◽  
Feeding Experiments ◽  
Aspergillus Ustus ◽  
P450 Enzyme ◽  
Derivatives Of

Abstract Oxepinamides are derivatives of anthranilyl-containing tripeptides and share an oxepin ring and a fused pyrimidinone moiety. To the best of our knowledge, no studies have been reported on the elucidation of an oxepinamide biosynthetic pathway and conversion of a quinazolinone to a pyrimidinone-fused 1H-oxepin framework by a cytochrome P450 enzyme in fungal natural product biosynthesis. Here we report the isolation of oxepinamide F from Aspergillus ustus and identification of its biosynthetic pathway by gene deletion, heterologous expression, feeding experiments, and enzyme assays. The nonribosomal peptide synthase (NRPS) OpaA assembles the quinazolinone core with d-Phe incorporation. The cytochrome P450 enzyme OpaB catalyzes alone the oxepin ring formation. The flavoenzyme OpaC installs subsequently one hydroxyl group at the oxepin ring, accompanied by double bond migration. The epimerase OpaE changes the d-Phe residue back to l-form, which is essential for the final methylation by OpaF.

scholarly journals Synthesis and Olfactory Characteristics of Hydroxyether Derivatives of Methyl Eugenol

2020 ◽  
Vol 24 (9) ◽  
pp. 1503-1507
Author(s):  
S.O. Okopi ◽  
L.M. Affiku
Keyword(s):  
Double Bond ◽  
Essential Oils ◽  
Plant Species ◽  
Chemical Transformation ◽  
Structural Modification ◽  
Methyl Eugenol ◽  
Naturally Occurring ◽  
Relationship Of ◽  
Derivatives Of ◽  
Functional Alteration

Methyl eugenol is a naturally occurring substance found in the essential oils of several plant species. It is a cheap and abundant material with a rather limited interest as perfuming ingredient. This research investigated the structure-odour relationship of methyl eugenol and its derivatives, focusing on the chemical transformation of the double bond to hydroxyether derivatives in a controlled manner. Two derivatives 2-(4-ethyl- 3-methoxybenzyl)oxirane (68.8% yield) and 1-(3,4-dimethoxyphenyl)-3-ethoxypropan-2-ol (63.58% yield), were synthesized from methyl eugenol. This research found that the odour characteristic of 2-(4-ethyl-3-methoxybenzyl)oxirane[floral, fresh, slight lime and sweet]compounds, is clearly different from the odours of the 1-(3,4-dimethoxyphenyl)-3-ethoxypropan-2-ol [Glue-like, pungent, and Caramel-like]. It is evident from our observations that double bond substitution and functional alteration of the methyl eugenol modifies the perceived odour of methyl eugenol  derivative. Thus, structural modification overall led to an increase in odour potency. Keywords: Fragrance, Methly-Eugenol, Ether, Olfactory characteristic, Epoxidation.

Über Derivate des Hydrazins, VII Zur Reaktivität von Bis(trimethylsilyl)aminoisocyanid / On Derivatives of Hydrazine, VII Reactivity of Bis(trimethylsilyl)aminoisocyanide

1977 ◽  
Vol 32 (9) ◽  
pp. 1003-1009 ◽  
Author(s):  
Nils Wiberg ◽  
Gerhard Hübler
Keyword(s):  
Double Bond ◽  
Oxidation State ◽  
Ring Cleavage ◽  
Reaction Paths ◽  
Stable Compound ◽  
Oxidizing Agents ◽  
Formal Oxidation State ◽  
Double Bond System ◽  
Bond System ◽  
Derivatives Of

The chemistry of bis(trimethylsilyl)aminoisocyanide (1) is determined by three reactive centres of the system : the hydrolyzable Si–N-bond, the oxidizable carbon in the formal oxidation state two, the additionable double bond system. Reactions of the oxygen stable compound 1 with halogens X2 or sulfenyl halides RSX as oxidizing agents gives compounds of type (Me3Si)2NNCX2 or (Me3Si)2NNCX(SR). Heterocumulenes such as CO2, CS2, RNCS (R = (Me3Si)2N), SO2 add to 1, leading to heterocycles, which decompose at higher temperatures by ring cleavage. With other heterocumulenes such as PhNCO, Me3SiNSO, Me3SiNSNSiMe3 products are found, the formation of which could be explained by reaction paths including the building and cleavage of heterocycles.

2',3'-O-Carbonyl derivatives of 6-azauridine in the synthesis of its 5-substituted and 5'-deoxy derivatives

1987 ◽  
Vol 52 (8) ◽  
pp. 2070-2082
Author(s):  
Pavel Drašar ◽  
Jiří Beránek
Keyword(s):  
Thionyl Chloride ◽  
Alkaline Hydrolysis ◽  
Triphenyl Phosphine ◽  
Carbonyl Derivatives ◽  
Tributyltin Hydride ◽  
Chloro Derivative ◽  
Ammonium Halides ◽  
Chloro Derivatives ◽  
Derivatives Of ◽  
Dichloro Derivative

Preparation of 2',3'-O-carbonyl derivatives of 5'-deoxy-6-azauridine and 6-azauridine using 1,1'-carbonyldiimidazole has been elaborated. 5'-Chloro and 5'-bromo derivatives were prepared by treatment of the 5'-O-mesyl derivative with quaternary ammonium halides, 5'-chloro derivatives also by direct halogenation with thionyl chloride in hexamethylphosphortriamide or with tetrachloromethane, triphenyl phosphine, and dimethylformamide. Derivatives of 5'-bromo-6-azauridine were reduced with tributyltin hydride to 5'-deoxy-6-azauridine compounds. 6-Azauridine 2',3'-carbonate (IVa) and its 5'-derivatives IVc and IVe on treatment with imidazole in dimethylformamide afforded 2,2'-anhydronucleosides IIIa-IIIc. The 2,2'-anhydro-5'-deoxy compound IIIc underwent alkaline hydrolysis to 5'-deoxy-1-β-D-arabino-pentofuranosyl-6-azauracil (VIa). Treatment of 2,2'-anhydro-5'-deoxy-5'-chloro derivative IIIb with hydrogen chloride led to 2',5'-dichloro derivative If.

Structure and Content of Dicyclopentadiene in Ethylene Propylene Dicyclopentadiene Terpolymers

1967 ◽  
Vol 40 (2) ◽  
pp. 563-568
Author(s):  
R. J. de Kock ◽  
A. Veermans
Keyword(s):  
Double Bond ◽  
Polymer Chain ◽  
Spectroscopic Methods ◽  
Double Bonds ◽  
Model Compounds ◽  
Ethylene Propylene ◽  
Infrared Spectroscopic ◽  
Polymerization Mixture ◽  
Derivatives Of

Abstract With the aid of model compounds—derivatives of endo- and exo-dicyclopentadiene—it has been established that a) the 9, 10-double bond (the double bond in the norbornane ring) is involved in the polymerization of dicyclopentadiene with ethylene and propylene, b) dicyclopentadiene, present in the polymerization mixture in the endo-configuration, occurs in the exo-configuration in the polymer chain. The same model compounds enable the dicyclopentadiene content of ethylene propylene dicyclopentadiene terpolymers to be determined by infrared spectroscopic methods. Use is made of the 3045 cm−1 band, which is characteristic of endo-cyclic double bonds in five-membered rings.

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