Iminoformylierung substituierter Crotonnitrile. III. Zur Stereochemie und innermolekularen Beweglichkeit von 4-Amino-1,1-dicyanbuta-1,3-dienen

Iminoformylation Reaction of Substituted Crotonnitriles. III. Stereochemistry and Intramolecular Mobility of 4-Amino-1.1-dicyano-buta-1.3-dienes ¹H- and ¹³C-n.m.r. spectroscopic investigations show the preference of s-trans configuration and the push-pull character of the investigated 4-amino-1,1-dicyano-buta-1,3-dienes. Dynamic ¹H- and ¹³C-n.m.r. data for the rotation process about the C N bond are determined. The activation energies are discussed with respect to electronic and steric effects of substituents and to solvents polarity.     

Cyclisierungsreaktionen β,γ-ungesättigter Kohlensäurederivate. XI [1] Untersuchungen zur Stereochemie der Cyclofunktionalisierung β,γ-ungesättigter Carbamidsäureester

Cyclization Reactions of β,γ-Unsaturated Derivatives of Carbonic Acid. XI. Investigation of Stereochemistry of the Cyclofunctionalization of β,γ-Unsaturated Carbamic Acid Esters N, N-Disubstituted β,γ-unsaturated urethanes 1 have been cyclized to 3,5-disubstituted oxazolidine-2-ones 3 by aromatic sulfenyl chlorides 2 . The stereochemistry of the products and the cyclofunctionalization reaction were investigated.     

Zur copolymerisation von α-methylstyrol und butadien. V. Bestimmung der chemischen heterogenität durch gelchromatographie

The distribution function of the compositional heterogeneity of copolymers from α-methyl styrene and butadiene has been determined from gel permeation chromatography by detection of refractive index and ultraviolet absorption.     

Zur Synthese von Polyfluoralkylestern der Fluorsulfonyl-difluoressigsäure und der α-Trifluormethylfluoressigsäure

On the Synthesis of Polyfluoroalkylesters of Fluorosulfonyl-difluoroacetic Acid and α-Trifluoromethylfluoroacetic Acid .     

Zur Auffindung von α-, β- und γ-Dehydrotocopherol in Weizenkeimöl mittels HPLC und GC/MS - ein Beitrag zur Analytik der Tocopherole

Finding of α-, β- and γ-Dehydrotocopherol in Wheat Germ Oil by HPLC and GC/MS - a Contribution to Tocopherol Analysis Fractions of β-tocotrienol/γ-tocopherol isolated from commercial wheat germ oils by preparative TLC were separated once more by HPLC. Three dehydrotocopherols (α-, β-and γ-) were found and identified by GC/MS. HPLC-retention data for plastochromanol-8 in these and corresponding fractions of Latex (Hevea brasiliensis) could be ascertained. The hypothetic 5,7-dimethyltocotrienol could not be found neither in the equivalent fractions of wheat germ oil and Latex nor in those of rude palm oil.     

Direkte und sensibilisierte Photoisomerisierung der α,δ-Phenylfulgide

Direct and Sensitized Photoisomerization of α,δ-Phenylfulgides The photoreactions starting from the E- and E-E-isomers of mono-, di-, tri- and tetra-(substituted-)phenylfulgides are investigated. The phenylfulgides show strong steric interactions in the molecular framework. For that reason internal conversion is the main deactivation process which increases in the series of mono-, tri- and tetraphenylfulgides. The α,δ-di-(substituted-)-phenylfulgides show the highest photoreactivity. At room temperature in no case luminescence is observed from any E(E-E)-, Z(E-Z, Z-E)- or Z-Z-phenylfulgid isomer of the substances under study. Intersystem crossing cannot compete neither with thermal deactivation nor can it be observed by applying both the internal and external heavy atom effect. The phenylfulgides show typical ππ*-photoreactivity: in the singlet state E-Z-isomerization about one double bond competes with electrocyclic ring closure; in the triplet state only simultaneous E-Z-isomerization about the two double bonds is observed. The steric and electronic substituent influences on the photoreactivity are interpreted. A first qualitative model of the isomerization reactions of the fulgides in the excited states is established.     

α-Substituierte Phosphonate. XXXIV. Zur Veresterung und N-Formylierung von α-Aminomethan-bisphosphonsäuren mit Orthoameisensäuretriethylester

α-Substituted Phosphonates. XXXIV. Esterification and N-Formylation of α-Aminomethane-bisphosphonic Acids with Triethylorthoformate In contrast to simple mono- and bisphosphonic acids esterification of dialkylaminomethanebisphosphonic acids with orthoformate (OAE) proceeds very slowly. Monoalkyl and monoarylaminomethanebisphosphonic acids, respectively react with OAE in constrast to analogous hydroxy compounds more readily primarily by formylating the N-atom and then esterification to formyl aminomethane bisphosphonictetraesters 10 . Acetaminomethanephosphonic acid ( 12 ) reacts without N-formylation, while the aminomethanebisphosphonic acid ( 14 ) reacted to give a mixture of mono- and bis-formylated products 15 and 16 . By acidic hydrolysis of 10 the ester- and formylgroups are splitt off, while the ester group can selectively be removed by reaction with Me₃SiBr/H₂O. – As shown by ¹H-, ¹³C- and ³¹P-n.m.r. spectroscopy the phosphorylated formamides 10 exists in two rotameres, the ratio depending on the solvent. The n.m.r. signals could be correlated to E-resp. Z-form undoubtedly by using shift-agents or the benzene-diluting technique. A rotational barrier of 22,8 kcal for 10c could be calculated.     

Natürliche Antioxidantien III Zur Kinetik der antioxidativen Wirkung von α-Tocotrienol

Natural Antioxidants III: Kinetics of Antioxidative Action of α-Tocopherols Kinetics of antioxidative action of α-tocotrienol was compared to that of other tocopherols. Specially purified methyl esters of total fatty acids of sunflower oil served as substrates, whose first ?stable”? autoxidation product is linoleic acid hydroperoxide. In all reactions studied, α-tocotrienol was somewhat more effective than α-tocopherol. The maximum inhibition was reached at a concentration of 0.02%. With increasing concentration, the well known phenomenon of reversion occurs with α-tocotrienol to a greater degree than with α-tocopherol. α-Tocotrienol, added in an amount of 0.12%, causes a more rapid decomposition of peroxides than α-tocopherol.     

Zur Analytik von Kohlenwasserstoffen mit Hilfe der Massenspektrometrie. III [1,2]. Qualitative und quantitative massenspektrometrische Bestimmung von Alkanen und Alkenen

Analysis of Hydrocarbon by Means of the Mass Spectrometry. III. Qualitative and Quantitative Mass Spectrometric Determination of Alkane and Alkene The rapid quantitative determination of alkanes and alkenes in products of the alkylation and oligomerisation of butanes and butanes is possible by use of electron-impact-mass-spectrometry with help of calibration factors with relatively small deviation, that were determined by ourselves in samples. The structure of C₈-, C₁₂- and C₁₆-alkenes is determined by mass spectrometry of the products of hydrogenation.