Solution Thermolysis Research Articles

Exploration into the (CH) 4 hydrocarbon manifold - thermal stabilization pathway of rac-tritwistatriene

The preparative potential of rac-tritwistatriene ( 2) as precursor for other novel (CH) 14 hydrocarbons is explored. Solution thermolysis generates the primarily desired pentaene 1 together with trienes 7 and 9. From FVP experiments, 1 is obtained together with triene 9 and pentaene 11 as thermodynamically more stable (CH) 14 isomers. The behavior of 1 in cycloaddition reactions is provisionally explored.

Generation of diatomic sulfur by solution thermolysis of 2,3-dithiabicyclo[2.2.1]hept-5-ene

2,3-Dithiabicyclo[2.2.1]hept-5-ene has been prepared at room temperature by the oxidation of cis-cyclopentene-3,5-dithiol and decomposes in solution at 130–160 °C to cyclopentadiene and diatomic sulfur, which has been intercepted.

Thermal behaviour of aryl γ-haloprcpargyl ethers

A systematic study of the behaviour of aryl γ-halopropargyl ethers under thermal condition was undertaken. Aryl γ-bromopropargyl ethers 2 underwent unique transformation in N,N-diethylanillne (215°C, 6 h) giving rise to a mixture of products 3 , 4 and 5 , whereas, under similar conditions aryl γ-chloropropargyl ethers ulbar|8, afforded 4-chlorochromenes, 9. A remarkable substituent and solvent effect has been observed in the thermolysis of these aryl γ-bromo and γ-chloropropargyl ethers, rendering this transformation as a method for the synthesis of a number of substit uted 4-bromochromenes 3 , 4-chlorochromenes 9 and chroman-4-ones 7 . In contrast, solution thermolysis of aryl γ-iodopropargyl ether 11 afforded aryl propargyl ether 1 as the major product.

Divergent thermal behaviour of phenoxymethyl phenyl sulphoxide under gas and condensed-phase conditions

A comparison is made between the behaviour of phenoxymethyl phenyl sulphoxide (2) under different thermolytic conditions. Passage of (2) through a quartz tube in the gas phase at 600 °C results in products which can be rationalised by assuming homolytic cleavage of the S–C bond and the generation of both the phenylsulphinyl (4) and phenoxymethyl (6) radicals which decompose by separate pathways to yield S-phenyl benzenethiosulphonate (3) and benzaldehyde, respectively. On the other hand, solution thermolysis of (2) in [2H8]toluene at 110 °C leads to a facile S→O 1,2-shift and the formation of thermally stable phenoxymethyl benzenesulphenate (9) in quantitative yield. A bimolecular oxygen-transfer mechanism is proposed for the conversion of (2) into (9) which is rationalised in terms of a double (stabilising) anomeric effect brought about by the acetal group in (9). Cross-over experiments support the mechanism.

ChemInform Abstract: Alkoxycarbonylnitrenes as Selective Intramolecular CH‐Insertion Reagents in Alicyclic Chemistry.

AbstractNitrenoformates, e.g. (IV), are generated a) by thermolysis (vapour‐phase (spray) pyrolysis or solution thermolysis) of azidoformates such as (Ia)/(Ib), (Ie), (If), (IXa), (IXb), (XIVa), (XIVb) or b) by photolysis of respective tetrachlorothienyl S,N‐ylides such as (Ic)/(Id).

Alkoxycarbonylnitrenes as selective intramolecular CH-insertion reagents in alicyclic chemistry

Intramolecular CH-insertion of cyclohexyl, cis- and trans-4-t-butylcyclohexyl, and cis- and trans-2-methylcyclohexyl nitrenoformates have been studied. The nitrenes were generated by vapour-phase (spray) pyrolysis or solution thermolysis of the corresponding azides, or by photolysis of tetrachlorothienyl S,N-ylides derived from the azides. The product ratios were principally (and predictably) dependent upon reaction temperatures (and thus conformational equilibria), these varying in the range 10–500°C. 17-Substituted estrone-derived nitrenoformates inserted either into the 12β(from 17β) or 14α(from 17α) CH sites while 17-derivatives with the nitrene on the end of a long inert group abstracted hydrogen from the steroid B-ring.

Open chain nitrogen compounds. Part X. Thermolysis of α-diazoacetanilides in methanol: a convenient synthesis of α-methoxyacetanilides from ethyl N-(arylazo)glycinate

α-Diazoacetanilides (4), which are readily available from the open-chain triazenes (2), undergo thermolysis in methanol solution to afford the α-methoxyacetanilides (5), an apparently rare type of ether/amide derivative. The methanolic thermolysis is inhibited by the presence of a tertiary amine in the solvent, suggesting that a carbocation, rather than a carbene, intermediate is involved in the conversion of the diazo-amide to the methyl ether. This hypothesis is supported by the retardation of the reaction in the presence of an electron-withdrawing group in the para position of the anilide. The conversion 4 → 5 was also observed, on a small scale, under photolytic conditions. It is suggested that the α-diazoacetanilide represents a useful synthetic equivalent for the synthon ArNHCOCH2+.

ChemInform Abstract: FERROCENESULFONYL AZIDE: STRUCTURE AND KINETICS OF SOLUTION THERMOLYSIS

Chemischer InformationsdienstVolume 16, Issue 52 Organoelement Compounds ChemInform Abstract: FERROCENESULFONYL AZIDE: STRUCTURE AND KINETICS OF SOLUTION THERMOLYSIS S. P. MCMANUS, Search for more papers by this authorJ. A. KNIGHT, Search for more papers by this authorE. J. MEEHAN, Search for more papers by this authorR. A. ABRAMOVITCH, Search for more papers by this authorM. N. OFFOR, Search for more papers by this authorJ. L. ATWOOD, Search for more papers by this authorW. E. HUNTER, Search for more papers by this author S. P. MCMANUS, Search for more papers by this authorJ. A. KNIGHT, Search for more papers by this authorE. J. MEEHAN, Search for more papers by this authorR. A. ABRAMOVITCH, Search for more papers by this authorM. N. OFFOR, Search for more papers by this authorJ. L. ATWOOD, Search for more papers by this authorW. E. HUNTER, Search for more papers by this author First published: December 31, 1985 https://doi.org/10.1002/chin.198552272AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume16, Issue52December 31, 1985 RelatedInformation

Ferrocenesulfonyl azide: structure and kinetics of solution thermolysis

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFerrocenesulfonyl azide: structure and kinetics of solution thermolysisSamuel P. McManus, Jerry A. Knight, Edward J. Meehan, Rudolph A. Abramovitch, Mercy N. Offor, Jerry L. Atwood, and William E. HunterCite this: J. Org. Chem. 1985, 50, 15, 2742–2746Publication Date (Print):July 1, 1985Publication History Published online1 May 2002Published inissue 1 July 1985https://doi.org/10.1021/jo00215a030RIGHTS & PERMISSIONSArticle Views114Altmetric-Citations5LEARN 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 (627 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Selective mixed coupling of carboxylic acids (I). - Electrolysis, thermolysis and photolysis of unsymmetrical diacyl peroxides with acyclic and cyclic alkyl groups

14 Unsymmetrical diacyl peroxides (R 1CO 2-O 2CR 2 with R 1: undecyl; R 2: e.g. methyl, propyl, pentyl, nonyl, 2-methylpropyl, 2-propyl, 2-pentyl, cyclopropyl, cyclobutyl, cyclohexyl) are prepared in 85 to 92 % yield. Square pulse electrolysis of dodecanoyl octanoyl peroxide ( li ) affords the unsymmetrical coupling product octadecane( 4 )ins poor yield and selectivity. Thermolysis or photolysis in solution produces preferentially 4 , but also considerable amounts of disproportionation products. At −78°C the neat peroxides are photolysed selectively to the mixed dimers. With straight chain and β-branched alkyl groups high yields are obtained (63 – 76 %), with cycloalkyl groups medium yields (42 – 56 %), and with α-branched diacyl peroxides moderate yields (20 – 33 %). A comparison of the mixed Kolbe-electrolysis with the low temperature photolysis of the neat peroxide demonstrates the superiority of the latter method in small scale conversion with regard to yield and selectivity.

Ring cleavage of a 3-azidothiophene: novel extrusion of acetylene

Mild thermal decomposition of ethyl 2-azido-3-(3-azido-2-thienyl)propenote (8) results in the cleavage of the thiophene ring with extrusion of acetylene and formation of ethyl 5-cyanoisothiazole-3-carboxylate (10), together with ethyl thieno[3,2-c]pyridazine-3-carboxylate (9). The former reaction represents the first fragmentation of a five-membered heteroaromatic β-nitrene to extrude an acetylene, and the latter reaction is a rare example of formal intramolecular coupling of nitrenes in solution thermolysis. The vinyl azide group is necessary for this cleavage of the thiophene ring and a mechanism is proposed in which the derived nitrene co-ordinates with the thiophene sulphur atom to faciliate ring fragmentation. The analogous furan does not fragment similarly. Diels–Alder cycloadditions of 4-phenyl-1,2,4-triazole-3,5-dione to 2-vinylthiophenes were investigated as an independent approach to the thieno[3,2-c]pyridazine system, but the fused 4-phenyl-1,2,4-triazoline-3,5-dione ring proved resistant to hydrolytic cleavage.

Skattebol type rearrangement via α-bromotrimethylstannyl cyclopropane thermolysis. What is the mechanism?

Solution thermolysis of the epimers 5 gave rise to separate sets of products, including, for one, Skattebol-type rearrangement. However, neither epimer produced a free carbene.

The solution thermolysis of 2-, 3-, and 4-(2-hydroxy-2-arylethyl)pyridines

The solution thermolysis of 2-, 3-, and 4-(2-hydroxy-2-arylethyl)pyridines

Thermolysis of 2-methoxy-2,5,5-trimethyl-Δ3-1,3,4-oxadiazoline

The principal product of gas phase thermal decomposition of 2-methoxy-2,5,5-trimethyl-Δ3-1,3,4-oxadiazoline (methoxyoxa-diazoline) was found to be 1-methoxy-1-[(1-methylethenyl)oxy]-ethane (vinyl ether). This arises from a selective 1,4-hydrogen shift in the carbonyl ylide intermediate. Fragmentation of the carbonyl ylide is the dominant process in the solution thermolysis of methoxyoxadiazoline. The phase and temperature dependence of this thermolysis is discussed in terms of the probable structure of the carbonyl ylide intermediate.

Evidence for the reactive spin state of 1,4-dehydrobenzenes

Two approaches have been used to investigate the spin state(s) of 1,4-dehydrobenzenes produced in the solution thermolysis of diethynyl olefins. One method relies on the spin correlation effect which postulates a relationship between the spin state of a caged radical pair and the ratio of cage and escape reactions (C/E) which may occur in the pair. When the 2,3-di-n-propyl-1,4-dehydrobenzene biradical (4) abstracts hydrogen from 1,4-cyclohexadiene, a radical pair is generated. If a mixture of 1,4-cyclohexadiene-d/sub 0/ and -d/sub 4/ is employed, it is possible, by performing a VPC-MS analysis, to determine the C/E ratio leading from the radical pair to the reduced product, o-dipropylbenzene (10). When this method was applied to the reaction of (Z)4-5,diethynyl-4-octene (3), C/E was found to be 0.6, independent of the concentration of 1,4-cyclohexadiene (between 0.1 and 10 M) in the chlorobenzene reaction solution. This result indicates the presence of the singlet state of 4 in the reaction of 3. Additional support for this analysis came from the reaction of 3,4-dimethyl-1,5-hexadiyn-3-ene (11) in hexachloroacetone solvent in a /sup 1/H NMR probe. The single polarized signal (emission) observed is attributed to the major product of the reaction, 1,4-dichloro-2,3-dimethylbenzene (12), obtained by chlorine abstraction from the solvent. The more » interpretation of this result indicates solvent trapping of the singlet state of the intermediate 2,3-dimethyl-1,4-dehydrobenzene, consistent with the chemical trapping study. These experimental approaches indicate that at least a substantial portion of the products formed from 1,4-dehydrobenzenes at elevated temperatures arise from the singlet state of the biradical. « less

Mechanisms of Thermal Decomposition of trans- and cis-Dialkylbis(tertiary phosphine)palladium(II). Reductive Elimination and trans to cis Isomerization

Abstract Series of trans- and cis-dialkylpalladium(II) complexes having tertiary phosphine ligands (L) of various basicities and bulkiness have been prepared and their thermolysis and isomerization mechanisms in solution have been studied. Examination of the cause of selective formation of cis-dialkyl isomers by using alkyllithium revealed a new type of trans to cis isomerization promoted by the alkyllithium. A process involving the formation of a trialkyl-palladate intermediate is proposed as a mechanism for the trans to cis isomerization. Evidence to support the mechanism has been obtained by experiments using LiCD3. Thermolysis of cis-PdR2L2 has been demonstrated to proceed through a unimolecular process initiated by a rate-determining dissociation of L to produce a three-coordinate “cis-PdR2L” which reductively eliminates the R groups. Addition of free ligand to the system containing cis-PdMe2L2 effectively blocks the reductive elimination pathway thus forcing the complex to be thermolyzed by a route involving liberation of methane. The second, novel type of trans to cis isomerization reaction proceeding via an intermolecular methyl transfer process has been discovered. As the crucial intermediate in the process a methyl-bridged complex formed between the partly dissociated three-coordinate species and undissociated complex has been postulated. Thermolysis of trans-PdMe2L2 has been found to proceed via initial isomerization to the cis form followed by reductive elimination. The trans-cis isomerization equilibrium greatly favors the cis form for complexes having phenyl-substituted phosphines. For the PEt3-coordinated palladium dimethyl, however, an equilibrium trans/cis ratio of 1.2 is reached at 39 °C. Factors influencing the stability of the palladium alkyls having the tertiary phosphine ligand are discussed on the basis of the present results as well as comparison of the thermolysis behavior of trans-PdEt2L2 and other transition metal alkyls. The presence of an energy barrier between the dissociated T-shaped intermediates trans-PdMe2L and cis-PdMe2L has been assumed. A unimolecular reductive elimination pathway proceeding from the T-shaped cis-PdMe2L intermediate through a Y-shaped transition state consistently accounts for the thermolysis as well as isomerization behavior of the trans-and cis-PdMe2L2.

Selective mixed coupling of carboxylic acids via unsymmetrical diacyl peroxides by electrolysis, thermolysis and photolysis

Unsymmetrical diacyl peroxides are prepared in 85–92 % yields. Their square pulse electrolysis affords unsymmetrical dimers in poor yield and selectivity. Whilst thermolysis or photolysis in solution produces high portions of disproportionation products, the photolysis of the neat peroxides at −78° C yields selectively 50–75 % of the mixed dimers.

Pyrolysis of phenylalkylsulphonyl azides and 2-phenethyl azidoformate. Selectivity of sulphonylnitrenes and contrast between sulphonyl- and carbonyl-nitrenes

Flash vacuum pyrolysis and solution thermolysis of Ph[CH2]nSO2N3 indicate that intramolecular addition to the phenyl group is preferred in solution, provided that up to an eight-membered sultam ring is formed, otherwise side-chain insertion results, while in the gas phase the latter process is favoured when n= 4,5, but not 3; some 5,6,7,8-tetrahydroquinoline is obtained when n= 3 at 990 °C, but 2-phenethyl azidoformate gave monomeric tetrahydro-1, 3-oxazino [3,4-a] azepin-2-one and 4-phenyl-oxazolidinone, but no dihydrocyclopenta [b] pyridine, even at 990 °C.

Triosmium clusters derived from benzylamine and benzyl alcohol: formation of a µ3-o-phenylene complex in the conversion of benzyl alcohol into benzene

Benzylamine reacts (125 °C) with [Os3(CO)12] to give mainly the µ-carbamoyl complex [Os3(CO)10H{µ-OCN-(CH2Ph)H}] together with small amounts of [Os3(CO)10H{µ-N(CH2Ph)H}] which may also be obtained by decarbonylation of the first product. The complex [Os3(CO)10(C8H14)2] gives (60–70 °C) the same products, but with the benzylamido-complex predominating. It is probable, but not established, that these derivatives are involved in the [Os3(CO)12]-catalysed carbonylation of benzylamine to (PhCH2NH)2CO. The analogue of only one of these, [Os3(CO)10H(µ-OCH2Ph)], is formed from benzyl alcohol, and thermolysis of nonane solutions of this derivative at 146 °C in sealed glass tubes gives C6H6, PhCHO, [Os3(CO)12], and [Os4(CO)12H4] only; related products are obtained from the 4-methyl-substituted analogue, while [Os3(CO)10H(µ-OCMePhH)] gives only PhCOMe as an organic product. A possible scheme for these degradations is discussed in terms of the intermediates [Os3(CO)9H2(µ-OCH2C6H4)] and [Os3(CO)9H2(µ3-C6H4) which have been isolated from reaction solutions flushed with N2. The complex [Os3(CO)9H2(µ3-C6H3Me-4)] is formed from both isomers [Os3(CO)10H(OCH2C6H4Me-2 or -4)]. Interconversions and structures (based on spectroscopic evidence) of the above complexes are described.

A new synthesis of 2-pyridones. Solution thermolysis of propargylic pseudoureas

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA new synthesis of 2-pyridones. Solution thermolysis of propargylic pseudoureasLarry E. Overman and Sadao TsuboiCite this: J. Am. Chem. Soc. 1977, 99, 8, 2813–2815Publication Date (Print):April 1, 1977Publication History Published online1 May 2002Published inissue 1 April 1977https://doi.org/10.1021/ja00450a076RIGHTS & PERMISSIONSArticle Views288Altmetric-Citations19LEARN 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 (395 KB) Get e-Alerts Get e-Alerts