bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photochemische Primärprozesse von Xanthenfarbstoffen. III. Blitzlichtspektroskopische Untersuchungen zum Einfluß von kationischen Mizellen auf die Photoredoxprozesse von Selenopyronin
Authors: Ortmann W. , Kassem A. , Fanghänel E. 
Published: December 2004

Photochemical Primary Processes of Xanthene Dyes. III. Investigations of the Influence of Cationic Micelles on the Photoredox Processes of Selenopyronine by Flash ExcitationCationic micelles have no influence on the decay of the triplet state of selenopyronine (3F+). The products of photoredox reactions 3F+ + 3F+ (F+) → F· + F and 3F+ + DABCO → F· + DABCO live longer in the presence of the cationic micelles. The reason for the change of the lifetime is a separation of the photoredox products by micelles. F. is stored in the interior of the micelles. The positively charged F and DABCO are repelled from the micelles and the electron back transfer is hindered.
Eine neue Synthese für 6H‐1,3‐Thiazine
Authors: Schulze K. , Richter C. , Richter F. , Mrozek E. , Weisheit R. , Achenbach F. 
Published: December 2004

A New Synthesis of 6H‐1,3‐ThiazinesA new method for the synthesis of 1,3‐thiazines is described. The addition of nucleophiles to γ‐isothiocyanatoallylchlorides (1a‐j) leads to functionalisation and subsequent cyclisation (nucleophilic cyclofunctionalisation). Reaction of secondary amines or alcohols under catalysis by tert. amines gives numerous 2‐dialkylamino‐ (3a‐w) or 2‐alkoxy‐6H‐1,3‐thiazines (4a‐p).
Ringöffnungs‐ und SubstitutionsReaktionen von 4,4‐Dihalogen‐pyrazolin‐5‐onen durch Nucleophile
Authors: Kirschke Klaus , Lutze Gerhard , Schmitz Ernst 
Published: December 2004

Ring Opening and Substitution Reactions of 4,4‐Dihalo‐pyrazolin‐5‐ones with Nucleophiles1‐Aryl‐4,4‐dihalo‐3‐methyl‐pyrazolin‐5‐ones (1a–c) undergo ring opening with alkoxides and form alkyl 3‐arylazo‐2‐halo‐2‐butenoats (2a–d). Analogous reactions take place with ammonia and amines.4‐Nitro‐phenoxide reacts with substitution of both halogens to the 4,4‐bis(4‐nitro‐phenyl)‐compound (5).Phenols are selectively orthobrominated by the title compounds 1a and b.
Selectivity in the Oxidation of Aliphatic Ketones by thallic sulphate in aqueous medium
Authors: Pechál Miroslav , Strašák Milan 
Published: December 2004

AbstractThe effects of temperature, structure and sulphuric acid concentration on the selectivity of the oxidation of aliphatic ketones (R1COR2) (1a–g) by thallic sulphate have been investigated. With increasing temperature the quantity of internal α‐hydroxyketone (3a–d) decreases and the quantity of 1‐hydroxyketone (2a–d) increases in the oxidation of methyl alkyl ketones (R2>CH3) (1a–d). The same concerns to the oxidation products of hexan‐3‐one (1e): 2‐hydroxy‐hexan‐3‐one (2e) and 4‐hydroxy‐hexan‐3‐one (3e), respectively. “The inverse selectivity temperature” (IST) for oxidation of linear methyl alkyl ketones (1a–c) and hexan‐3‐one (1e) has been found. With the use of the linear free‐energy relationship it has been found that the selectivity of the reaction decreases with increasing the polar and steric effects of substituents R1, R2. With increasing the sulphuric acid concentration the selectivity of the oxidation of methyl alkyl ketones (1a, 1d) increases.
Theoretical description of solvent effects. X. Theoretical investigation of the Tautomerism of Nucleic Acid Bases of biological importance in the gas phase and in solution
Authors: Bartzsch C. , Weiss C. , Hofmann H.‐J. 
Published: December 2004

AbstractThe tautomerism of the nucleic acid bases cytosine and adenine and some of their derivatives is investigated by means of semiempirical MO methods. The influence of the solvent is estimated using various versions of the reaction field model. In the cases under investigation here, the medium influence does not favour “rare” tautomeric forms having other coding properties in DNA replication process than the “normal” nucleic acid base tautomers. Thus, the probability of their participation in spontaneous mutations seems to be very low.
Diels‐Alder‐Reaktionen. IX. Über Bildung und Thermolyse der isomeren Tricyclopentadiene
Authors: Ramhold K. , Moll K. K. , Roschka E. , Zimmermann G. , Krukowka Th. Smola L. 
Published: December 2004

Diels‐Alder‐Reactions. IX. On the Formation and the Thermolysis of Isomeric TricyclopentadienesThe formation of isomeric tricyclopentadienes by codimerisation of cyclopentadiene with endo‐ and exo‐dicyclopentadiene between 100 and 140°C in the liquid phase, and the retrodiene reaction of the main isomeres of the tricyclopentadiene fraction by gas phase thermolysis were studied kinetically between 230 and 310°C. The rate constants and the parameters of activation were determined.
Photochemical Dediazoniation of Arene Diazonium Salts sensitized by zink meso‐tetraphenyl porphyrin
Authors: Becker H. G. O. , Lehmann T. , Schütz R. 
Published: December 2004

AbstractPhotoexcited zink tetraphenylporphyrin (ZnTPP) reacts with arene diazonium salts via electron transfer according to the oxidation mechanism. This is proved by ESR spectroscopy of ZnTPP+ formed and the fact that N2 and ZnTPP+ are formed in a molar ratio.Due to very different life‐times of1(ZnTPP)* and 3(ZnTPP)* it is possible to differentiate between singlet and triplet electron transfer reactions using different diazonium salt concentrations. In this way, the respective quenching constants are determined by means of flash spectroscopy.Due to electron back transfer the singlet reaction at high concentrations of diazonium salts (0.1M) is inefficient (quantum yield 0.1), whereas back electron transfer is symmetry‐forbidden in the triplet reaction which, therefore, proceeds with high quantum yields, mearly reaching the ISC quantum yield.From differences between the triplet quenching constants determined by flash spectroscopy and from product quantum yields, respectively, and from corresponding kinetic models it is concluded that the triplet reaction proceeds via a reversibly formed triplet exciplex.Complexes of meso tetraphenyl porphyrin containing Pb(II), Sn(IV), Mn(II), Ni(II), Cu(II) and Fe(III), respectively, have lower sensitization activities decreasing in the order, given in the text.
Elektrochemische Reduktion und Azokupplung kernchlorierter p‐Dimethylaminobenzendiazoniumsalze Hammett‐Korrelationen
Authors: Fanghänel E. , Kriwanek J. , Ortmann W. , Bagal I. L. , Lebedeva N. W. , El'cov A. V. 
Published: December 2004

Electrochemical Reduction and Azo‐coupling of Ring Chlorinated p‐Dimethylaminobenzenediazonium Salts. Hammett‐CorrelationsThe polarographic half‐wave potentials of ring halogenated 4‐dimethylaminobenzenediazonium salts (6a–6j) can be linearly correlated with the total σ‐constants Σσkorr (E1/2 = (0.25 Σσkorr + 0.33) V; r = 0.995), if for the dimethylamino group of the 3‐ or 3,5‐halogenated derivatives corrected σ′p‐constants are used. The Σσkorr‐values determined can be used to correlate the influence of substituents on the azo‐coupling kinetics (lg k/k0 = 2.46 Σσkorr; r=0,988).
Zur Bildung von Ethoxy‐hydrochinazolinon durch Reaktion von Estercarbonylsauerstoff mit Cyan‐enamin
Authors: Bischoff Christian , Schröder Edith 
Published: December 2004

Formation of Ethoxyhydroquinazolinone by Attack of an Estercarbonyloxygen at a Cyano GroupBy the reaction of ethyl‐2‐oxo‐cyclohexanecarboxylate with cyan amide 4‐ethoxyhexahydroquinazolin‐2‐one (12) is formed. Butyl‐2‐oxo‐cyclopentanecarboxylate and cyan amide yield butyl‐3‐cyanamino‐cyclopent‐1‐en‐carboxylate (14). 2‐Oxocyclohexane‐carboxamide (1) and ethyl‐cyanoacetate form with sodiumhydroxide 4‐cyano‐octahydroisoquinolin‐1, 3‐dione (17) and with ammonium acetate ethyl cyclohexylidene‐cyanoacetate‐2‐carboxamide (18). 18 and ammonia, hydrazine, or cyclohexylamine form the salts of cyanohydroquinazolindione 20a–c, respectively.
Untersuchungen zur Hydrolysestabilität von 4‐Arylmethyliden‐2‐pyrazolin‐5‐onen
Authors: Fanghänel E. , Akhlaq M. S. , Grossmann N. 
Published: December 2004

Investigations on the Hydrolytic Stability of 4‐Arylmethylidene‐2‐pyrazolin‐5‐onesThe 4‐Arylmethylidene‐2‐pyrazoline‐5‐ones S are not stable under aqueous alkaline conditions. By the substitution of R3 with electron donor substituents S reacts preferably yielding aldehyde A and 2‐pyrazoline‐5‐one P, while with electron acceptor substituents S forms 4,4′‐aryl‐methylidene‐bis‐2‐pyrazoline‐5‐one B. The intermediate of hydrolysis is 4‐(arylhydroxymethyl)‐2‐pyrazoline‐5‐one SOH.The second order rate constants of the reaction of S with hydroxidions and with 2‐pyrazoline‐5‐ones P− are determined. The dependence of the hydrolytic decomposition of S on the pH vaue substituents and temperature is suitable for the intermediate formation of SOH.
Substituenteneffekt und Mechanismus der thermischen Rücktautomerisierung belichteter Salicylidenaniline
Authors: Grummt U.‐W. 
Published: December 2004

Substituent Effect and Mechanism of the Thermal Retautomerization of Flashed Salicylidene AnilinesV‐shaped Hammett plots are obtained with a series of p‐substituted salicylidene anilines for the relaxation rate of their phototautomers. This is interpreted by a change‐over in the mechanism from O‐protonation (donor substituents) to NH‐deprotonation (acceptor substituents) as rate determining initial steps in alcoholic solvents. The observed acid and base catalysis strongly support the assumption of an o‐quinoid geometry of the phototautomer.
Synthese von 2,4‐Bisalky(aryl)amino‐6‐cyanamino‐1,3,5‐triazinen
Authors: Freiberg Renate , Bulka Ehrenfried 
Published: December 2004

Synthesis of 2,4‐Bisalkyl(aryl)amino‐6‐cyanamino‐s‐triazinesReaction of 2,4‐bisalkyl(aryl)amino‐6‐chloro‐s‐triazines with disodiumcyanamide to 2,4‐bisalkyl(aryl)amino‐6‐cyanamino‐s‐triazines (3a–g) strongly depends on the solvent used. In dimethylformamide by‐products predominate. The best results are found in dimethylsulphoxide.
Zur Telomerisierung von Isopren mit Palladium‐Komplexen bei niedriger Temperatur
Authors: Berger R. , Gaube W. 
Published: December 2004

On the Telomerization of Isoprene at Low TemperatureThe telomerization of isoprene was carried out by means of a catalyst system of Pd(acac)2/PPh3 and complexes of the type Pd(acac)2 · L (L = PPh3; py; NHEt2) at 298 K. The reaction in methanol gave 8‐methoxy‐2, 7‐dimethyl‐octa‐1, 6‐diene (3a), 8‐methoxy‐3, 7‐dimethyl‐octa‐1, 6‐diene (4a) and oligomer products. 2, 7‐Dimethyl‐octa‐1,3, 7‐triene (1), 8‐i‐propoxy‐2, 7‐dimethyl‐octa‐1, 6‐diene (3b) and oligomer products were obtained in i‐PrOH. During the reaction a formation phase of the catalyst was observed.
Acetals and Ethers. XVI [1] Hydrolysis of 2‐[2‐(ω‐Hydroxyalkoxy)alkyl]‐substituted 1,3‐Dioxolanes and 1,3‐Dioxanes in Aqueous Solution of Hydrochloric Acid
Authors: Piasecki Andrzej 
Published: December 2004

AbstractThe rate constants of hydrolysis of 2‐[2‐(ω‐hydroxyalkoxy)alkyl]‐substituted 1,3‐dioxolanes and 1,3‐dioxanes (1–6) in aqueous HCl solution were determined. For two selected acetals, the parameters of active complexes were also evaluated. The acetals studied were found to be more stable than 2‐alkyl‐substituted 1,3‐dioxolanes and 1,3‐dioxanes. The presence of ether‐oxygen in β‐position with respect to the acetal grouping in molecules of 2‐[2‐(ω‐hydroxyalkoxy)alkyl]‐substituted 1,3‐dioxolanes and 1,3‐dioxanes was the stability determining factor.
An Improved Synthesis of 1,4‐Benzo‐ and 1,4‐Naphthoquinones Bearing Active Substituents
Authors: Syper Ludwik , Kloc Krystian , Młochowski Jacek 
Published: December 2004

AbstractThe synthesis of 1,4‐benzoquinones and 1,4‐naphthoquinones 3a–j carrying substituents such as methoxyl, ally or oxiranyl was substantially improved. The 1‐methoxy‐4‐methoxy‐methyloxy 2a–d, g–k or 1,4‐bis(methoxymethyloxy) derivatives 2e‐f were used, as a substrates instead of 1,4‐dimethoxy derivatives 1a–j hitherto used and they were oxidized with silver(II) dipicolinate. Among numerous examples, the synthesis a of new analog of ubiquinone 3d with the oxiranyl substituent, being a new bioactivated alkylating agent, is reported.
Elektrochemische Spaltung von 3‐Halogen‐1,2,4‐thiadiazolen zu Cyanimidothiocarbonaten
Authors: Rüttinger H.‐H. , Walek W. , Matschiner H. 
Published: December 2004

Electrochemical Cleavage of 3‐Halogen‐1,2,4‐thiadiazoles to Cyanimidothiocarbonates3‐Halogen‐1,2,4‐thiadiazole‐5‐sulfenylchlorides (5a‐j) are easily accessible by the halogenation of eyanimidodithiocarbonates (1). As electrophilic synthetic building blocks they react with basic olefines or electron‐rich aromates to the corresponding alkylthio‐or arylthio derivatives. The electrochemical reduction of these compounds led to substituted cyanimidomithiocarbonates (7a‐e), not being accessible otherwise.
Studies on the Regioselectivities in the Oxidation of Simple Alkyl Aromatic Hydrocarbons by Molecular Oxygen
Authors: Pritzkow Wilhelm , Thomas Gerda , Willecke Lothar 
Published: December 2004

AbstractThe products of the autoxidation of various simple alkyl aromatic hydrocarbons were reduced by LiAlH4, and the alcohols formed were determined by gas chromatography. In the cases of 2‐phenylbutane, 3‐phenylpentane, and 2‐p‐tolylbutane a considerable fragmentation of the intermediate tertiary alkoxy radicals was proved. On the basis of the analytical results relative reaction rates of the various C–H‐bonds in the hydrocarbons studied were calculated. It is shown that the attack at C–H bonds which are not activated by the aromatic nucleus cannot be neglected and may be of great importance for the kinetics of the oxidation of alkyl aromatic hydrocarbons.
Synthesen von C‐Nucleosiden und C‐Nucleosidanaloga. IV. Darstellung und Charakterisierung von 5(S)‐bzw. 5(R)‐Tetrahydroxybutyl‐3‐methyl‐1,3‐oxazolidinen
Authors: Börner A. , Kristen H. , Peseke K. , Michalik M. 
Published: December 2004

Syntheses of C‐Nucleosides and Analogs of C‐Nucleosides. IV. Preparation and Characterization of 5(S)‐ and 5(R)‐Tetrahydroxybutyl‐3‐methyl‐1,3‐oxazolidines1‐Deoxy‐1‐methylamino‐D‐hexitols 1,2,3 react with ketendithioacetals 4 to give the acyclic C‐nucleosides 5,6 and 7. The structure of the compounds were verified by means of periodate oxidation and spectroscopic investigations. Some properties of the acyclic C‐nucleosides were investigated by acetalation reactions on the tetrahydroxybutyl chain.
NMR‐study of the stereochemistry and dynamic behaviour of thioacrylamides
Authors: Kleinpeter E. , Tadesse Tsegaye , Abegaz Berhanu 
Published: December 2004

AbstractSeveral model thioacrylamides, Me2NCH = C(R)C(S)NMe2 (R = H, Ph — 2a, b) and (p)MeOC6H4NHCHC(R)C(S)NMe2 (R = H, Ph — 3a, b) have been synthesized. The 1H‐n.m.r. spectra have been taken for discussing the E/Z‐isomerism of the thioacrylamides and the assignment further strengthened by an added LIS‐study. The 2‐unsubstituted compounds have been found to exist exclusively in preferred configurations/conformations: 2a — E(s‐cis); 3a — Z(s‐cis); the 2‐phenylsubstituted analogs are of divergent behaviour: in 2b the C(S)NMe2 moiety is found to be twisted out of the common plane, and 3b prefers the flat s‐trans conformations (E(s‐trans) ⇌ Z(s‐trans)). The compounds show restricted rotations about C1, N‐ and C3, N‐partial double bonds. The corresponding rotational barriers, determined as ΔG‐values by dynamic n.m.r. spectroscopy, are discussed with respect to (i) the resonance branch at C1, (ii) the influence of substituents, and (iii) the effect of steric hindrance in the thioacrylamide moiety generally.
Komplexkatalyse mit Technetiumverbindungen: Hydroformylierung mit Technetiumcarbonyl‐Katalysatoren
Authors: Kaden L. , Lorenz B. , Wahren M. 
Published: December 2004

Complex Catalysis with Technetium Compounds. Hydroformylation with Technetiumcarbonyl CatalystsThe hydroformylation reaction of cyclohexene (1), propene (2) and 1‐octene (3) was studied using Tc2(CO)10 and Tc(CO)10/P(n‐C4H9)3, resp., as catalysts in solution. For comparison experiments have also been made with Mn2(CO)10, Mn2(CO)10/P(n‐C4H9)3 and Re2(CO)10/P(n‐C4H9)3 as catalysts for the hydroformylation of 1.There is always a competition between hydrogenation and hydroformylation.Tc2(CO)10/P(n‐C4H9)3 gave the best results in activity and selectivity within the subgroup VII complexes studied, but is a rather poor catalyst compared with the cobalt or rhodium compounds.
Synthesis of (3′,3′‐Dimethyloxiranyl)quinones and (Dimethylacetyl)quinones as Potential Cytostatics
Authors: Kloc Krystian , Młochowski Jacek , Syper Ludwik , Mordarski Marian 
Published: December 2004

Abstract1,4‐Benzoquinones and 1,4‐naphthoquinones carrying 3′,3′‐dimethyloxiranyl, dimethylacetyl or oxiranylmethyloxy substituents (1, 2 or 3) have been synthesized. The methods presented involved epoxidation of a sterically overcrowded double bond as a crucial step for synthesis of (3′,3′‐dimethyloxiranyl)quinones 1. Reaction of aryllithium derivatives with 2‐chloro‐2‐methyl‐propanol unexpectedly led to (dimethyl)acetylarenes 11 subsequently oxidized to (dimethylacetyl)‐quinones 2. High cytotoxicity of 1 against KB cells has been revealed contrary to significantly lower activity of 2 and 3. The structure‐activity relationship was discussed in terms of current theory of biologically activated alkylating agents.
Synthese und spektrale Charakterisierung von blauen Benzenazofarbstoffen
Authors: Thiel W. , Mayer R. , Jauer E.‐A. , Modrow H. , Dost H. 
Published: December 2004

Synthesis and Spectral Characterization of Blue Azo Dyes of the Benzene Series53 Donor‐acceptor substituted azo dyes of the benzene series were prepared by diazonium‐coupling reactions (1 a–s) or halogen‐cyanide exchange (→2 a–x, 3 a–j). Described are the preparation of the amines 4 a–m and the coupling compounds 5 a–t and the procedure of diazotizing and coupling.The colouristic and spectroscopic data show that compounds of the general formula 1 are excellent brilliant blue azo dyes useful for dyeing polyester material.
Tautomerism in 6‐Arylpyridazin‐3(2H)‐thiones and some of their reactions
Authors: Shams Nabil A. , El‐Kafrawy A. F. , El‐Sawy O. M. , Fekry Ismail M. 
Published: December 2004

Abstract6‐Arylpyridazin‐3(2H)‐thiones exist mainly, if not entirely, in the thione form (1). This was shown by spectroscopic studies on some of these compounds and their substitution products either on the nitrogen or on the sulphur [in the mercaptopyridazine form (2)]. However, the reacting tautomer of these compounds was found to be dependent upon the basicity of the reaction medium. Selected 6‐arylpyridazin‐3(2H)‐thione derivatives react with formaldehyde and sec‐amines to give N‐2‐aminomethyl derivatives (8) [thione form (1)]. On the other hand oxidation and alkylation reactions gave disulphides (10) and S‐alkyl derivatives (7) [mercapto form (2)].
Pyryliumverbindungen. 33 [1] 2‐Dialkylamino‐2H‐thiopyrane aus 2,4,6‐Triaryl‐thiopyryliumsalzen
Authors: Zimmermann Thomas , Fischer Gerhard W. 
Published: December 2004

Pyrylium Compounds. 33. 2‐Dialkylamino‐2H‐thiopyrans from 2,4,6‐Triaryl‐thiopyrylium Salts2,4,6‐Triaryl‐thiopyrylium salts 7 react with dialkylamines in diethyl ether to give stable crystalline 2‐dialkylamino‐2H‐thiopyrans 8, the structure of which is in accordance with their u.v., n.m.r. and mass spectra. The chemical properties of 8 parallel those of structurally analogous 2‐alkoxy‐ and 2‐dialkylamino‐2H‐pyrans and 2‐alkoxy‐2H‐thiopyrans. Thus, on heating 2‐dimethylamino‐2,4,6‐triphenyl‐2H‐thiopyran (8a) with methanol the corresponding 2‐methoxy‐2H‐thiopyran 9 is formed. Nitromethane and ethyl cyanoacetate give rise to ring transformations yielding 1,3,5‐triphenyl benzene (10) and 2,4,6‐benzonitrile (11), respectively. From 8a electrophiles (e.g. mineral acids, methyl iodide, benzoyl chloride) regenerate the initial thiopyrylium system by taking over the dialkylamino group.
Umsetzung von Bromderivaten des 6β‐Bromcholest‐4‐en‐3‐ons mit NaBH4 und 13C‐NMR‐spektroskopische Charakterisierung der Reduktionsprodukte
Authors: Römer J. , Scheller D. , Grossmann G. 
Published: December 2004

Reaction of Bromo Derivatives of 6β‐Bromocholest‐4‐en‐3‐one with NaBH4 and 13C‐NMR Spectroscopic Characterization of the Reduction ProductsBromo derivatives of 6β‐bromcholest‐4‐en‐3‐one (1a–f) were reduced with sodium borohydride. The main product of the reduction of 2α,6β‐dibromcholest‐4‐en‐3‐one (1b) was 2α‐bromocholesterol (2b). In other cases the corresponding derivatives of 6β‐bromocholest‐4‐en‐3β‐ol (3a) were formed. The chemical shifts of all new products were determined. They confirmed the structure of these new compounds.
Partialsynthesen von Cardenoliden und Cardenolid‐Analogen. X. Synthese 22‐O‐substituierter Cardenolide sowie Untersuchungen über den oxidativen Abbau von Cardenoliden mit Kaliumpermanganat
Authors: Lindig Claus 
Published: December 2004

Partial Syntheses of Cardenolides and Cardenolide Analogues. X. Synthesis of 22‐O‐Substituted Cardenolides and Studies on the Oxidative Degradation of Cardenolides with Potassium PermanganateThe stereoisomeric 20,22‐dihydroxy‐cardanolides 2a and 3a as well as the oxalic acid half ester of the 3β‐acetoxy‐14,21‐dihydroxy‐5β,14β‐pregnan‐20‐one (4a) and 3β‐acetoxy‐20‐oxo‐5β,14β‐pregnane‐21,14‐lactone (5) were identified as intermediates of oxidative degradation of digitoxigenin 3‐acetate with potassium permanganate.2a and 3a, after selective acylation in 22‐position, were converted to the 22‐acyloxy‐cardenolides 7a and 7b via dehydration or acetoxyelimination after selective acetylation of the 20‐hydroxy group. Saponification of both 7a and 7b yields the very stable 22‐hydroxy‐cardenolide 8a.The molecular biological activities of the 22‐substituted cardenolides were investigated and discussed.
Phosphororganische Antioxidantien. IV. Chemisch induzierte Polarisation von 31P‐Kernen in der Reaktion cyclischer Phosphite mit Hydroperoxiden
Authors: König T. , Grossmann G. , Schwetlick K. , Rüger C. 
Published: December 2004

Organophosphorus Antioxidants. IV. Chemical Induced Polarization of 31P Nuclei in the Reaction of Cyclic Phosphites with Hydroperoxides31P‐n.m.r. CIDNP is observed in the reactions of cyclic o‐phenylene and ethylene phosphites with hydroperoxides. Polarized phosphorus nuclei appear especially in the phosphonate and phosphate regions. Application of Kaptein's rule shows that these products are cage or escape products of secondary or tertiary radical pairs. Solvent molecules are involved in the formation of the tertiary radical pairs.The concentration of the products formed from polarized 31P nuclei is very low.
The Oxidation of Primary Trimethylsilyl Ethers to Aldehydes – a selective conversion of a primary hydroxy group into an aldehyde group in the presence of a secondary hydroxy group
Authors: Mahrwald Rainer , Theil Fritz , Schick Hans , Schwarz Sigfrid , Palme Hans‐Joachim , Weber Gisela 
Published: December 2004

AbstractSecondary trimethylsilyl ethers (2a–d) are not affected by Collins reagent in dichloromethane at 0°C. Primary trimethylsilyl ethers (4a–e), however, are smoothly oxidized to aldehydes (5a–e) under these conditions. In agreement with these observations trimethylsilylated diols or polyols with primary and secondary trimethylsilyloxy groups (6–9) are oxidized selectively by Collins reagent to trimethylsilyloxy aldehydes (10–13).
Studies on the kinetics of the Hydrolysis of Some Substituted Benzylidene Benzoichydrazide with differential pulse polarography
Authors: Kamal M. M. , Temerk Y. M. , Ahmed M. E. , Ahmed Z. A. 
Published: December 2004

AbstractThe kinetics of the hydrolysis of some substituted benzylidene benzoichydrazide 1a–e in 40% (v/v) ethanol buffer mixture have been investigated by differential pulse polarography. The mechanism of the hydrolysis in acidic buffer solutions is discussed.The catalysis by H⊕ involves the conversion of the hydrazide compound to its conjugated acid in a rapid preequilibrium step followed by a slow attack of water. The effects of pH, water, organic solvents and molecular structure on the reaction rate and the activation are investigated.