Double Bond System Research Articles

Reactions of carbonyl compounds in the presence of phase transfer catalysts

1. Quantum chemical CNDO/BW calculations with optimization of geometries have been carried out on the keto and enol forms of acetone, mesityl oxide, and methyl ethyl ketone, and on the carbanions resulting from various types of deprotonation in these compounds. 2. The keto forms of acetone and mesityl oxide are considerably more stable than the enol forms, while the enolate anions resulting through from heterolytic rupture of the OH bond in the enol forms pass over into the keto form anions with zero activation energy. 3. The calculated gas-phase acidities of the compounds in question here increase in the order: acetone, methyl ethyl ketone, mesityl oxide. 4. Proton detachment from the γ-CH3 group of theβ-form of mesityl oxide, from the secondary C atom of theα-form, or from the hydroxyl group of the enol form leads, in every case, to the same anion structure, namely anα-form carbanion with an unconjugated system of single and double bonds. This, and the anion resulting from proton detachment from theα-methine C atom of theβ-form, are the most stable of the mesityl oxide carbanions. 5. The H atoms bound to the secondary C atom are the most acidic hydrogens in methyl ethyl ketone. Theα-CH3 group acidity is the same in each of the compounds covered by this work.

Cumulated double bond systems as ligands : XI. Di- an tri-nuclear iron complexes resulting from the reaction of [Fe 2(CO) 9] with RNSNR (R = t-C 4H 9, 4-MeC 6H 4); crystal and molecular structure of (Fe 2(CO) 6{RNC(O)S}] [Fe 3(CO) 9(RNS)S] and [Fe 3(CO) 9(RN)S

Reaction of RNSNR (R = t-C 4H 9, 4-MeC 6H 4) with (Fe 2(CO) 9[leads to the rupture of one or two NS double bonds as evidenced by the formation of a number of complexes containing RNS, RN and S fragments. In the case of R = t-C 4H 9 and 4-MeC 6H 4 the RNS fragment behaves as a four-electron donor ligand, with the NS bond still double, and as a six-electron donor ligand with the NS bond single, bridging two iron atoms in [Fe 2(CO) 7(RNS)] and [Fe 2(CO) 6(RNS)], respectively. Insertion of CO into the NS bond of [Fe 2(CO) 6(RNS)] yields [Fe 2(CO) 6{RNC(O)S}]; a crystal structure determination has been carried out for the product with R = 4-MeC 6H 4. Heating of the solid complex affords azotoluene, which is also isolated from the reaction mixtures. In the case of R = t-C 4H 9[Fe 2(CO) 6S 2], [Fe 3(CO) 9S 2] and [Fe 3(CO) 9(RNS)S] are also formed. A crystal structure determination of the last compound reveals a prismane type structure, in which both a six-electron donor RNS fragment and a four-electron donor S atom are linked to the three iron atoms. For R = 4-MeC 4H 4 a different trinuclear iron complex [Fe 3(CO) 9(RN)S] was isolated, and the structure was established by a crystal structure determination; a nitrene fragment (RN) as well as a S atom are both triply bridging to a non linear array of three iron atoms of the Fe 3(CO) 9 skeleton.

ChemInform Abstract: POTASSIUM‐GRAPHITE AS SELECTIVE REDUCING AGENT FOR ACTIVATED DOUBLE BOND SYSTEMS

Chemischer InformationsdienstVolume 10, Issue 16 Preparative Organic Chemistry ChemInform Abstract: POTASSIUM-GRAPHITE AS SELECTIVE REDUCING AGENT FOR ACTIVATED DOUBLE BOND SYSTEMS M. CONTENTO, M. CONTENTOSearch for more papers by this authorD. SAVOIA, D. SAVOIASearch for more papers by this authorC. TROMBINI, C. TROMBINISearch for more papers by this authorA. UMANI-RONCHI, A. UMANI-RONCHISearch for more papers by this author M. CONTENTO, M. CONTENTOSearch for more papers by this authorD. SAVOIA, D. SAVOIASearch for more papers by this authorC. TROMBINI, C. TROMBINISearch for more papers by this authorA. UMANI-RONCHI, A. UMANI-RONCHISearch for more papers by this author First published: April 17, 1979 https://doi.org/10.1002/chin.197916139AboutPDF 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 onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume10, Issue16April 17, 1979 RelatedInformation

Potassium-Graphite as Selective Reducing Agent for Activated Double Bond Systems

Potassium-Graphite as Selective Reducing Agent for Activated Double Bond Systems

Cumulated double bond systems as ligands : X. N-sulfinylaniline complexes of rhodium(I) and iridium(I) of the type [MCl(PR 3) 2L] in which L is coordinated via the π-NS and via the sulfur atom respectively; crystal and molecular structure of [RhCl(P-i-Pr 3) 2(4-MeC 6H 4NSO)]; determination of the 1J( 103Rh 15N) by 15N NMR spectroscopy

Each of the compounds [MCl(Pr 3) 2(ArylNSO)] (M = Rh I, Ir I; R = i-Pr, Cy: Aryl = C 6H 5, 4-MeC 6H 4, 4-ClC 6H 4, 2,4,6-Me 3C 6H 2 appears to exist as two isomers both in the solid state and in solution. The molecular and single crystal structure of one of the isomers of [RhCl(P-i-Pr) 3) 2(4-Me 6H 4NSO)] shows that the N-sulfinylaniline ligand is in the cis-configuration and coordinated to the rhodium atom via the sulfur-atom. The ligand lies in a plane which includes the rhodium atom and is in agreement with the Rh-S distance of 2.10 Å. IR results of the compounds (solid and solutions), 21P NMR data and 15N NMR of a 15N labelled compound, which yielded a 103Rh 15N coupling constant of 15.5 Hz, show that in the second isomer the N-sulfinylaniline ligand is probably bonded to the metal atom via the π-NS bond. The ratio of the metal-π-NS bonded isomer and the metal-S bonded isomer decreases in the order Aryl = 4-ClC 6H 4 > C 6H 5 > 4-MeC 6H 4; R = i-Pr > Cy and M = Rh > Ir. The interconversion of the two isomers is intramolecular and becomes observable on the 31P NMR time scale at about 40° C for M = Rh. In the case of [Ir(P-i-Pr 3) 2(4-MeC 6H 4NSO)], cyclometallation of the sul- finylaniline is observed via the ortho-carbon atom, whereas cyclometallation via P-i-Pr 3 is observed when the ortho-positions are blocked by methyl groups, e.g. when L = 2,4,6-Me 3C 6H 2NSO.

CHARGE TRANSFER COMPLEXES BETWEEN POLYENES AND AROMATIC ACCEPTORS

Abstract. Both the cone pair electron donating ability of a polyene Schiff base and the strength of the bond formed indicate a weakening of the complex formed with increase in the conjugated double bond system.

Cumulated double bond systems as ligands : VIII. N-sulfinylaniline and sulfurdiimine complexes of platinum(O) of the type [Pt(PPh 3) 2L] in which L is π-bonded to Pt; crystal and molecular structure of [Pt(PPh 3) 2-2,4,6- Me 3C 6H 2NSO)]; determination of 2J( 13xP 15N) and 1J( 195Pt 15N) by 31P and 195Pt NMR

A crystal and molecular structure determination of [Pt(PPh 3) 2(2,4,6-mesitylNSO)] shows a side-on coordination via the NS unit to Pt 0, while the mesityl group is in the cis configuration with respect to SO. The same structure persists in solution, as shown by IR, UV, 1H-, 31P- and 195Pt-NMR studies on [Pt(PPh 3) 2(RNSO)] (R = Ph, 4-tol, 2-tol, 3,5-xylyl and 2,4,6-mesityl). In the case of [Pt(PPh 3) 2(Ph 15NSO)], 31P- and 195Pt-NMR gave the cis and trans-couplings 2 J( 31PPt 15N), 1 J( 31P 195Pt) and 1 J( 195Pt 15N). The PPh 3 groups interchange their positions intramolecularly, probably via a rotation about the Pt(NS) axis. From the isotopic shifts ( 15N) in the vibrational spectra of both the free and coordinated PhNSO it is concluded that there is hardly any coupling between ν(SO) and ν(NS). In the light of these conclusions, the unstable [Pt(PPh 3) 2(RNSNR)] complexes, for which N-coordination has been tentatively proposed on the basis of the IR and UV spectra, were reinvestigated. It may now be concluded from 13P- and 195Pt-NMR that for [Pt(PPh 3) 2(Ph 15NS 15NPh)] the sulfurdiimine is also side-on coordinated via one NS bond. At elevated temperatures the complex is fluxional, and it is proposed that, in addition to a probable rotation about the Pt(NS) bond, there is also an intramolecular migration of the (PPh 3) 2Pt

Cumulated double bond systems as ligands: IX. Insertion of platinum(0) in the NS bond of 2,1,3-benzothiadiazole with concomitant P [sbnd]C bond rupture, yielding a novel complex [formula omitted]. Crystal and molecular structure and 31P NMR results

Reaction of [(PPh 3) 2Pt(C 2H 4)] with 5,6-dimethyl-2,1,3-benzothiadiazole affords [ P t 2 S { N ( 6 − μ − N ︹ − 4 , 5 − M e 2 C 6 H 2 ) } ( μ − P P h 2 ) ( P P h 3 ) 2 P h ] . A crystal structure determination shows that one of the Pt-atoms is inserted into one of the N S bonds. The two Pt-atoms are bridged by the amino groups produced by this insertion, and by a diphenylphosphido group which is formed by insertion of the other Pt-atom into a P C bond. The bond distances in the six-membered heterocyclic P t S N C C − μ − N ︹ ring indicate an extensive electron delocalization. The 31P-NMR spectrum reveals a large upfield shift for the bridging diphenylphosphido group, which is consistent with its presence in a four-membered ring.

ChemInform Abstract: Cumulated Double Bond Systems as Ligands. Part 7. N,N′‐Diarylsulfurdiimine Complexes of Nickel(0) and Platinum(0) of the Type [(PPh3)x·M(RNSNR)]y and Formation of a Novel Complex [Pt(II)[SN(l‐NHR1)(R)](PPh3)2] from [Pt[0](RNSNR)(PPh3)2] Via an Irreversible Intramolecular Rearrangement Involving N‐C(aryl) Bond Formation and N=S Bond Breaking.

ChemInform Abstract: Cumulated Double Bond Systems as Ligands. Part 7. N,N′‐Diarylsulfurdiimine Complexes of Nickel(0) and Platinum(0) of the Type [(PPh3)x·M(RNSNR)]y and Formation of a Novel Complex [Pt(II)[SN(l‐NHR1)(R)](PPh3)2] from [Pt[0](RNSNR)(PPh3)2] Via an Irreversible Intramolecular Rearrangement Involving N‐C(aryl) Bond Formation and N=S Bond Breaking.

Studies on the cutaneous sensitization reaction of guinea pigs to purified aromatic chemicals

The sensitization reactions to purified cinnamic aldehyde and its chemically related substances were investigated using the maximization test on guinea pigs. Mutual cross-sensitivities were also examined. Cinnamic aldehyde was found to be the most potent sensitizer in this series, and a strong cross-sensitizer. From the chemical structures of these substances, the following speculations were made. There was a tendency that as the number of hydrocarbons of alkyl groups replacing the alpha-hydrogen in the molecule increased, the rate of sensitization reaction declined. The conjugated system of double bonds was suspected to be a determinant factor in relation to the sensitization ability of the substances in this series.

Borverbindungen : X. Ringerweiterungen von 1,3,2-diazabora-cycloalkanen mit phenylisocyanat bzw. -isothiocyanat

During the aminoboration of appropriate double bond systems with 1,3,2-diazabora-cycloalkanes the heterocyclic ring system is expanded by insertion of two atoms of the double bond system. Collected data of comparative compounds enable us now to give a more detailed description of the reaction between a NCX group (X = O, S) and the BH bond in 1,3,2-diazabora-cycioalkanes as well as of the medium sized boron heterocycles formed.

Cumulated double bond systems as ligands: VII. N,N′-diarylsulfurdiimine complexes of nickel(0) and platinum(0) of the type [(PPh 3) xM(RNSNR)] y and formation of a novel complex [ [formula omitted]HR′)(R)](PPh 3) 2] from [Pt 0(RNSNR)(PPh 3) 2], via an irreversible intramolecular rearragement involving NC(aryl) bond formation and NS bond breaking

The complexes [Ni(PPh 3)(4-tolylNN-4-tolyl)] 2 and [Pt(PPh 3) 2(RNSNR)] (R = 4-tolyl, 4-Cl-phenyl and 3,5-xylyl) are reported. It is suggested that the Nicomplex is dimeric, and spectroscopic data indicate that the NSN units are bridging via a σ(NNi) and π((NS)Ni) bond. The platinum complexes are monomeric and occur in two isomeric forms: in CHCl 3 (at −30°C) the complex is probably three coordinated, with the RNSNR unit in the trans, trans configuration and linked to Pt via one of the N atoms. In CD 3NO 2 the complex is four-coordinated with the sulfurdiimine acting as a bidentate ligand coordinated to Pt via both N atoms. The three coordinated platinum complex is fluxional between −30 to +30°C, probably because of migration of the Pt atom from one N atom to the other. At +30°C a slow irreversible process occurs which leads to the formation of [ Pt[SN(1-N HR′)(R)](PPh 3) 2]. This compound has been characterized by X-ray crystallography and spectroscopic methods. A possible mechanism for the formation of this novel platinum(II) complex involves an initial intramolecular redox process, resulting in oxidation of platinum(0) to platinum(II), followed by concerted NS bond rupture, H-migration, and NC(aryl) bond formation.

Synthesis of 1,5‐dideazariboflavin

Abstract1,5‐Dideazariboflavin, an analog of riboflavin containing the original conjugated double bond system between positions 1 and 5, was synthesized by the condensation of 4,5‐dimethyl‐ N‐ribitylanthranilaldehyde and the sodium salt of 2,4,6‐piperidinetrione.

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

Abstract 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.

Reactions with heterocyclic diazonium salts: New routes for the synthesis of pyrazolo[1,5‐c]‐1,2,4‐triazoles and pyrazolo[1,5‐c]‐as‐triazines

Abstract3‐Phenylpyrazole‐5‐(liazonium chloride (1) couples with α‐chloro derivatives of acetylacetone, ethyl acetoacetate and aceto‐o‐anisidine to yield the corresponding pyrazole‐5‐yl hydrazonyl chloride derivatives 2a‐c. Compounds 2a,b were cyclised to yield either the pyrazolo[1,5‐c]‐1,2,4‐triazole derivatives 3a,b or the pyrazolo[1,5‐c]‐as‐triazines 4a,b depending on the applied reaction conditions. Compound 2c cyclised only into 3c under different cyclization conditions. The pyrazolo[1,5‐c]‐as‐triazine derivatives 4c‐e could be prepared via condensation of 2a with potassium cyanide. Compound 2d reacted with aromatic thioles and with sodium benzene‐sulphonate to yield the pyrazolo[1,5‐c]‐as‐triazine derivatives 6a‐d. Compound 1 reacted with activated double bond systems to yield pyrazolo[1,5‐c]‐as‐triazines 8a,b and 9.

Cumulated double bond systems as ligands : VI. Carbonyl compounds of chromium(0), molybdenum(0) and tungsten(0) containing sulfurdiimine ligands. Mechanism of the fluxional process and resonance Raman results

The preparation and properties are reported of Mo(CO) 5(RNSNR) (R = = Me,Et,i-Pr) and M(CO) 6 − x (5,6-dimethyl-2,1,3-benzothiadiazal) x x = 1; M = Mo and W; x = 1,2). In all cases the sulfurdiimine is linked as a monodentate ligand to the metal via the N-atom. All the complexes show fluxional behaviour. This is attributed to a gliding movement of the metal atom along the NSN system. Resonance Raman spectra of M(CO) 5(RNSNR) (M = W, R = i-Pr; M = Cr, R = Me,Et), W(CO) 5(5,6-dimethyl-2,1,3-benzothiadiazal) and M(CO) 4 (t-BuNSN-t-Bu) (M = Cr, Mo) show a vibrational coupling of the metal to sulfurdiimine CT transition not only with vibrations of the sulfurdiimine but also with the symmetric stretching vibration of the cis carbonyls in the complex.

Ovatifolin, a sesquiterpene lactone

Ovatifolin, C17H22O5, is a sesquiterpene lactone isolated from the aerial parts ofPodanthus mitiqui Lindl. (Compositae) collected near Pichidangui, Chile. Extracts of the plant exhibit cytotoxic activity against KB cell cultures. The pale yellow crystals belong to the orthorhombic space groupP212121 with cell dimensionsa = 8.159(1),b = 6.640(1), andc = 29.314(4) A. Data were collected on an automatic diffractometer and the structure was solved by direct methods. The model was refined anisotropically to anR value of 0.047 using all 1742 measured intensities. The 10-memberedtrans-trans-germacradiene ring adopts a chair-chair conformation with C(4) and C(10) methyl groups orientedsyn on the β face of the molecule. The conformation leads to a crossed double-bond system in which transannular interactions shift the ultraviolet absorption to 210 nm. The five-membered lactone ring adopts a distorted chair conformation and istrans-fused to the 10-membered ring.

Cumulative double bond systems: thermolysis of benzoyl peroxide in the presence of bisaryliminosulphur derivatives

Thermal decomposition of benzoyl peroxide in the presence of bisaryliminosulphur derivatives (ArN:S:NAr) affords the corresponding azobenzene (ArN:NAr) and diphenyl disulphide. It is suggested that the products originate from a bridged thiadiazolidinyl radical (8) formed by attack of the phenyl radical at sulphur followed by intramolecular cyclization.

Etude cinetique par RPE de la deshydrogenation thermique du polyacrylonitrile

The study of a remarkable property of the paramagnetism of PAN pyrolyzates has allowed following of the kinetics of dehydrogenation of a PAN homopolymer as well as oxygen binding on these pyrolyzates and to determine the kinetic and thermodynamic parameters of these two processes. The dehydrogenation of PAN, which occurs even in the absence of oxygen, occurs immediately after the thermal cyclisation of nitrile groups; it creates conjugated double bond systems (responsible for the paramagnetism) simultaneously with electron donor centres (responsible for the semi-conducting and catalytic properties) where molecular oxygen can be adsorbed, thus partially diminishing the paramagnetism.

The electrophysical properties of polytolans and polydiphenylbutadiyne and the relationship between these and supermolecular structure

A polymer of tolan, obtained by thermal polymerization, and polymers of tolan and diphenylbutadiyne, obtained by anionic polymerization, have been studied by the space charge-limiyted current method. The energy of activation for conduction, the mobility and concentration of the charge carriers and the density and depth of the traps were found. It is shown that in polymers containing a conjugated double bond system there are traps grouped about fundamental trapping level.