Reactions Of Alkoxy Research Articles

An experimental study of the reactivity of terpinolene and <i>β</i>-caryophyllene with the nitrate radical

Abstract. Biogenic volatile organic compounds (BVOCs) are intensely emitted by forests and crops into the atmosphere. They can rapidly react with the nitrate radical (NO3) during the nighttime to form a number of functionalized products. Among them, organic nitrates (ONs) have been shown to behave as reservoirs of reactive nitrogen and consequently influence the ozone budget and secondary organic aerosols (SOAs), which are known to have a direct and indirect effect on the radiative balance and thus on climate. Nevertheless, BVOC + NO3 reactions remain poorly understood. Thus, the primary purpose of this study is to furnish new kinetic and mechanistic data for one monoterpene (C10H16), terpinolene, and one sesquiterpene (C15H24), β-caryophyllene, using simulation chamber experiments. These two compounds have been chosen in order to complete the few experimental data existing in the literature. Rate constants have been measured using both relative and absolute methods. They have been measured to be (6.0 ± 3.8) ×10-11 and (1.8 ± 1.4) ×10-11 cm3 molec.−1 s−1 for terpinolene and β-caryophyllene respectively. Mechanistic studies have also been conducted in order to identify and quantify the main reaction products. Total organic nitrates and SOA yields have been determined. Both terpenes appear to be major ON precursors in both gas and particle phases with formation yields of 69 % for terpinolene and 79 % for β-caryophyllene respectively. They are also major SOA precursors, with maximum SOA yields of around 60 % for terpinolene and 90 % for β-caryophyllene. In order to support these observations, chemical analyses of the gas-phase products were performed at the molecular scale using a proton transfer reaction–time-of-flight–mass spectrometer (PTR-ToF-MS) and FTIR. Detected products allowed proposing chemical mechanisms and providing explanations through peroxy and alkoxy reaction pathways.

Spectroscopic and structural aspects of the reactions of 1,4-quinones with sulfur and nitrogen nucleophiles

Abstract A series of 1,4-benzoquinone derivatives from 2,5-dichloro-3,6-diethoxy-1,4-benzoquinone and 2,6-dichloro-3,5-diethoxy-1,4-benzoquinone were prepared by nucleophilic substitution reactions of sulfur and nitrogen nucleophiles. Spectral techniques ( 1 H NMR, 13 C NMR, FT–IR, and LC–MS) were employed to structurally characterize the reaction products of alkoxy, chloro substituted-1,4-benzoquinones with thiols and amines in the presence of sodium carbonate in ethanol at room temperature. The orientations and the regioselectivity of the reactions of alkoxy, chloro substituted-1,4-benzoquinones with various thiol and amine nucleophiles are discussed.

ChemInform Abstract: Integrated Reactions Using Addition to Conjugated Imines and Iminium Salts

AbstractReview: 18 refs.

Reactions of alkoxy and peroxy radicals formed upon the decomposition of hydroxyperoxide groups in the artemisinin derivatives

The enthalpies of intramolecular reactions of alkoxy and peroxy radicals formed from polyatomic artemisinin hydroperoxides and of their bimolecular reactions with C—H, S—H, and O—H bonds of biological substrates were calculated. The activation energies and rate constants of these reactions were calculated using the intersecting parabolas method. The decomposition of artemisinin hydroperoxides can initiate the cascade of intramolecular oxidation reactions involving radicals R·, RO·, HO·, HO2·, and RO2·. The main sequences of transformation of these radicals were established. The oxidative destruction of the artemisinin peroxy derivatives generates radicals RO2·, HO·, and HO2· in an amount of 4.5 radicals per peroxide derivative molecule on the average. The kinetic scheme of oxidative transformations of the hydroperoxide with four OOH groups and radicals formed from it was constructed using this radical as an example.

2,5-Dihydro-1,3,4-oxadiazoles and Bis(heteroatom-substituted)carbenes

2,5-Dihydro-1,3,4-oxadiazoles with heteroatom substituents at C-2 (also known as corresponding Delta(3)-1,3,4-oxadiazolines) are very useful materials for the thermal generation of acetoxy(alkoxy)-, dialkoxy-, alkoxy(aryloxy)-, diaryloxy-, alkoxy(alkylthio)-, bis(alkylthio)- and alkoxy(amino)-carbenes. Such carbenes are relatively nucleophilic and react with a variety of electrophilic functional groups. This Account reviews our work to prepare 2,5-dihydro-1,3,4-oxadiazoles and apply them to the synthesis of other target molecules. Carbenes bearing alkoxy substituents at the carbene carbon can be looked upon as acetals of carbon monoxide. Their reactions with electron-deficient alkenes or alkynes can afford acetals of cyclopropanones or cyclopropenones. Although such products may be formed by concerted cycloaddition, initial formation of one bond to produce zwitterions is likely in some cases. In addition, the reactions of these molecules with carbonyl compounds could involve acetals of alpha-lactones as intermediates. Although we have isolated some acetals of cyclopropanones, we have not isolated the other intermediates. However, some of the products we observe probably resulted from these intermediates. For example, dimethoxycarbene reacts with maleic anhydrides to generate six-membered rings by apparent carbonyl addition followed by an acyloxy group transfer. Similarly, dimethoxycarbene reacts with thiocarbonyl compounds, such as xanthates, by apparent carbonyl addition and transfer of the alkylthiyl group to the erstwhile carbene carbon. Reaction of ROC:(OR)' with an alcohol R''OH or a phenol should generate chiral (racemic) orthoformates. Similarly, reaction of alkoxy(alkylthiyl) carbenes with alcohols could generate chiral (racemic) dialkyl thiyl orthoformates. 2,5-Dihydro-1,3,4-oxadiazoles are particularly useful for synthetic applications because they are easily prepared and reasonably stable, thermal sources of bis(heteroatom)carbenes. Such carbenes react with a variety of electrophilic functional groups, often with rearrangement of initial products. Those products, many of them new, could be used as starting materials toward other synthetic targets. Isolation of products from the reaction is relatively simple because the coproducts of thermolysis of the oxadiazoles are primarily N(2) and a ketone, such as acetone. Thus, 2,5-dihydro-1,3,4-oxadiazoles should be part of every synthesis chemist's toolbox.

Reactions of alkoxy and peroxy radicals with carbon monoxide

Experimental rate constants of the reactions HO· + CO → H· + CO2, RO· + CO → R· + CO2, HO2· + CO → HO· + CO2, and RO2· + CO → RO· + CO2 are analyzed in the framework of the intersecting-parabolas model. The transition states of the additions of the methoxy and methylperoxy radicals to carbon monoxide were calculated by quantum-chemical methods. The reactions occur in two consecutive steps: first the HO· (RO·, RO2·) radical adds to CO and then the resulting unstable intermediate radical decomposes to evolve CO2. The kinetic parameters of these reactions are calculated by two methods (using the intersecting-parabolas model and the quantum-chemical method). The activation energies and rate constants of a series of RiO· + CO and RiO2· + CO reactions are calculated. A comparison of the kinetic parameters suggests close similarity between the transition states in the additions of the O-centered radicals to CO and olefins.

Reactions of alkoxy and amino derivatives of silacyclobutane with amino alcohols

2-(N,N-Dimethylamino)ethanol readily replaces the MeO and Et2N groups in 1-methoxy-1-methyl-, 1,1-dimethoxy-, 1-diethylamino-1-methyl-and 1,1-bis(diethylamino)-1-silacyclobutanes to form dimethylaminoethoxy derivatives. Triethanolamine and N,N-bis(2-hydroxyethyl)glycinamide split the silacyclobutane ring in 1,1-dimethoxy-1-silacyclobutane to form 1-propylsilathrane and 1-propyl-2-azasilathran-3-one, respectively.

PENTACOORDINATE ACYCLIC AND CYCLIC ANIONIC OXYSILICATES. A 29Si NMR AND X-RAY STRUCTURAL STUDY

Abstract Variable temperature 29Si NMR spectral measurements revealed the formation of acyclic anionic silicates, [R'nSi(OR)5-n] [K, 18-crown-6], n = 0-3, from reactions of alkoxy and aryloxysilanes with the respective potassium alkoxide or potassium aryloxide in the presence of 18-crown-6. This elusive class of substances has been proposed as model intermediates in the sol-gel process. In the case of [PhSi(OCH2CF3)4][K, 18-crown-6], isolation as a crystalline solid was achieved. The29Si chemical shifts move progressively downfield from Si(OR)5 to R'Si(OR)4 − to R'2Si(OR)3 −. Pentaalkoxysilicate anions react rapidly with pinacol to form the corresponding five-coordinated bicyclic anionic silicate. Independent synthesis and an X-ray structural study verified the formation of the bis(pinacolate), [(Me4C2O2)2SiO-i-Pr][K, 18-c-6] (1). For comparison of structural distortions, the synthetic and X-ray characterization of the related anionic oxysilicates, [(C6H4(CF3)2CO)2SiC6H11][Et4N] (2) and [(CH4O2)2SiC6H11][...

ChemInform Abstract: Simple, High‐Yield Synthesis of Unsymmetrically Functionalized Bishydrazone and α‐Azino Hydrazone Derivatives by Reaction of Alkoxy‐ and Aminocarbonylazoalkenes with Tosylhydrazones.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Simple, High-Yield Synthesis of Unsymmetrically Functionalized Bishydrazone and α-Azinohydrazone Derivatives by Reaction of Alkoxy- and Aminocarbonylazoalkenes with Tosylhydrzones

The reaction of alkoxy- or aminocarbonylazoalkenes with tosylhydrazo- nes, in the presence of sodium hydride in a catalytic amount, leads to unsymmetrically functionalized bishydrazones that are easily conver- ted into related α-azinohydrazones

Reactions of alkoxy and hydroxy radicals generated photochemically from hydroperoxide molecules

In the present work\(\dot OH\) as well as HRO. radicals were generated in the photochemical interaction of 1,2-benzanthracene with α-ethyl phenyl hydroperoxide /HROOH/ in C6H6 and CCl4 at 304 K.\(\dot OH\) radicals were trapped by C6H6. The main reaction of HRO. radicals is hydrogen abstraction from the hydroperoxide group of HROOH. Although OH radicals are less selective, the hydrogen abstraction is the main process during their interaction with aromatics in contrast to reactions in aqueous solutions, where addition to the benzene ring is the rate-determining process in CCl4: $$\begin{array}{*{20}c} {k_{\dot OH + HRO\underline {OH} } /k_{\dot OH + \underline {HR} OOH} = 2.5 \pm 0.5 and} \\ {k_{\dot OH + C_6 H_6 } /k_{\dot OH + \underline {HROOH} } = /1.2 \pm 0.15/xlo^{ - 2} .} \\ \end{array}$$

The study of the pyrolysis of alkyl nitrites in a field ionization mass spectrometer

The pyrolysis behaviour of ethyl, n-propyl, n-butyl and iso-butyl nitrite at low pressures was investigated in the temperature range 150–510°C, using a field ionization mass spectrometer. The three pyrolysis steps (loss of NO to form an alkoxy radical, loss of CH 2O to form an alkyl radical, and loss of an olefine to form a secondary alkyl radical or hydrogen) could be readily identified. The alkoxy radicals can be identified only indirectly via secondary reactions on the surface of the field ionization emitter, while alkyl radicals undergo surface reactions to a lesser extent and thus can be identified directly. The proportion of free alkyl radicals increases with increasing chain length and branching of the alkyl nitrite, while the optimum temperature for formation of alkyl radicals decreases correspondingly. The results not only give information on the pyrolysis behaviour of alkyl nitrites but also shed light on the reactions of alkoxy and alkyl radicals on the surface of a field ionization emitter.

Free-radical chemistry of organophosphorus compounds. III. .alpha. vs. .beta. Scission in reactions of alkoxy and thiyl radicals with trivalent organophosphorus derivatives

Free-radical chemistry of organophosphorus compounds. III. .alpha. vs. .beta. Scission in reactions of alkoxy and thiyl radicals with trivalent organophosphorus derivatives

Halo-substituted 1-buten-3-ynes

Some halo-substituted 1-buten-3-ynes were synthesized by the reaction of alkoxy-, alkylthto-, and alkyl-1-buten-3-ynes with alkaline metal hypohalites.

.alpha. vs. .beta. scission in reactions of alkoxy and thiyl radicals with diethyl alkylphosphonites

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT.alpha. vs. .beta. scission in reactions of alkoxy and thiyl radicals with diethyl alkylphosphonitesWesley G. Bentrude, Eric R. Hansen, Wajid A. Khan, and Peter E. RogersCite this: J. Am. Chem. Soc. 1972, 94, 8, 2867–2868Publication Date (Print):April 1, 1972Publication History Published online1 May 2002Published inissue 1 April 1972https://doi.org/10.1021/ja00763a059RIGHTS & PERMISSIONSArticle Views492Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (269 KB) Get e-Alerts Get e-Alerts

Reactions of tungsten hexafluoride with sulphite esters and with trimethyl phosphite. Preparation and reactions of alkoxy- and phenoxytungsten (VI) pentafluorides

Tungsten hexafluoride reacts with dimethyl, diethyl, and diphenyl sulphites to give the corresponding alkoxy- or phenoxy-tungsten(VI) pentafluoride, ROWF5, and the fluorosulphite ester, ROS(O)F. MeOWF5 and PhOWF5 are stable at 20°, but EtOWF5 decomposes to give WOF4 and EtF. MeOWF5 and (MeO)2PF are the initial products from the reaction of WF6 with trimethyl phosphite but subsequent reactions occur to give [(MeO)3PMe]+[WOF5]–, (MeO)2P(O)Me, (MeO)(F)P(O)Me, MeP(O)F2, and WOF4,OP(OMe)2Me. The products obtained depend on the reaction conditions. Structures for the tungsten–fluorine compounds are suggested from their 1H and 19F n.m.r. spectra and the reactions of MeOWF5 with (MeO)3P, C6H6, and C5H5N are reported.

Reactions of alkoxy -?-ketoesters of the acetylene series with secondary amines

1. We have synthesized and proved the structure of the aminoketoesters formed by addition of secondary amines to acetylenic ketoesters. 2. Study of the PMR spectra of the aminoketoesters led to the conclusion that addition of secondary amine to the triple bond of acetylenic ketoesters leads to trans-isomers.

Reactions of alkoxy(chloromethyl)methylsilanes with sodium diethyl phosphate and with sodium dimethylphosphinate

The reactions of alkoxy(chloromethyl)methylsilanes with sodium diethyl phosphate and with sodium dimethylphosphinate provide a method for the preparation of some silicon-phosphorus organic compounds containing an Si-C-O-P linkage and functional groups attached to the silicon atom.

Chemistry of organic free radicals in the vapor phase. II. Reactions of alkoxy and alkylperoxy radicals; energetics of some alkyl radical reactions

Considers hydrocarbon oxidation, peroxide decomposition, decomposition of nitrite and nitrate esters, and the energetics of some simple alkyl radical reactions.