bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photolysis of some N‐cycloalkyl‐N‐nitrososulfonamides. The interaction between a small cycloalkyl group and an amidyl radical centre
Authors: Dekker E. E. J. , Engberts J. B. F. N. , de Boer Th. J. 
Published: September 2010

AbstractN‐Cycloalkyl‐N‐nitrosotosylamides 1a‐c with three‐, four‐ and five‐membered cycloalkyl groups have been photolysed in CFCl3. The cyclopropyl derivative 1a isomerises to 2a, an imine containing a C‐nitroso group, by successive N‐NO homolysis and overall migration of the nitroso group from nitrogen to carbon (cf. Scheme 2). In methanol the solvent adds to the imine double bond. The cyclopentyl derivative 1c does not undergo isomerisation at all, but after N‐NO homolysis, the remaining radical 4c eliminates β‐hydrogen from the ring, thus forming the imine 7c with an unruptured ring. Alternatively, the radical 4c abstracts hydrogen from the solvent to give the N‐cyclopentyl‐sulfonamide 6c (cf. Scheme 3).The cyclobutyl derivative 1b takes an intermediate position, and is therefore incorporated in both schemes. It shows a strong influence of the temperature (−10° to −80°) on the ratio of ring‐closed vs. ring‐opened products (cf. Table I).Quenching experiments suggest that in all cases products are derived from singlet excited states.
Heavy‐atom effects in the photoreactions of halogenated aromatic compounds
Authors: Ruzo L.O. , Sundström G. , Hutzinger O. , Safe S. 
Published: September 2010

AbstractThe photoreactions of various halogenated naphthalenes and biphenyls in methanol at 290‐310 nm are affected by addition of heavy‐atom lithium salts. The triplet decay rate appears to be increased relative to the reaction rate resulting in overall rate decrease. The effect of iodide is greater than that of added bromide while the reaction rates in the presence of chloride or in the absence of external heavy atoms proceed in the order of decreasing bond strength of the carbon‐halogen bonds.
Réactions de condensation avec des carbanions de sulfonyl cétones. Propriétés chimiques des composés d'addition
Authors: Ladurée D. , Paquer D. , Rioult P. 
Published: September 2010

AbstractThe dianions from a number of α‐sulfonyl ketones have been obtained using sodium hydride and n‐butyllithium. The dianions can produce with carbon disulfide, S‐dimethyl dithiocarbonate or dimethyl trithiocarbonate different addition compounds. The chemical reactions of these compounds with phosphorus pentasulfide, phenylhydrazine and methanol (in acid medium) have been investigated.
Reactivity of ring systems with two hetero atoms. I. On the reaction of 1,4‐dithiins with n‐butyllithium
Authors: Schoufs M. , Meyer J. , Vermeer P. , Brandsma L. 
Published: September 2010

AbstractThe reaction of 1,4‐dithiin (1) with n‐butyllithium has been examined. At −110° in tetra‐hydrofuran 2‐lithio‐1,4‐dithiin (2) is sufficiently stable to allow of the preparation of derivatives. Anion (2) undergoes ring opening by a 1,2‐elimination at −60°; subsequent methylation and hydrolytic work‐up gives ZHC≡CS‐CHCHSMe (6), or Z−MeC≡C−S−CHCH−SMe (7). At about −5° butyllithium attacks sulfur in the intermediary Z−LiC≡C−S−CHCH−SLi (4), leading to Z−BuS−CHCH−SLi (8), and LiC≡CLi.These results are not in agreement with the mechanism proposed by Parham et al. for benzo‐1,4‐dithiin and 2,5‐diphenyl‐1,4‐dithiin. We studied also the reactivity of 2,6‐dimethyl‐1,4‐dithiin (13), and 2,6‐ di‐tert‐butyl‐1,4‐dithiin (25), towards butyllithium. Starting from 13 the otherwise, difficultly accessible tri‐ and tetramethyl‐1,4‐dithiins could be prepared in high yield.The ring opening provides a valuable method for the synthesis of stereochemically pure Z‐1‐(alkynylthio)‐2‐(alkylthio)alkenes and Z‐1‐(butylthio)‐2‐(alkylthio)alkenes.
A novel synthesis of 10‐aryl‐9‐arsaanthracenes
Authors: Weustink R.J.M. , Jongsma C. , Bickelhaupt F. 
Published: September 2010

Abstract10‐Aryl‐9‐arsaanthracenes (3b,c,d) were conveniently synthesized by flash vacuum pyrolysis at ∼ 500° of 10‐mono‐ and di‐substituted 9‐aryl‐9,10‐dihydro‐9‐arsaanthracenes (11a‐f). The yield of 10‐aryl‐9‐arsaanthracenes is found to depend upon the substituents at C(10). The occurrence of radical intermediates is discussed briefly.
Synthesis of 9,11‐dideoxy‐9a‐homoprostaglandins
Authors: Eggelte T.A. , de Koning H. , Huisman H.O. 
Published: September 2010

AbstractThe synthesis of three 9,11‐dideoxyprostaglandins in which the cyclopentane moiety is replaced by a six‐membered ring, is described. Starting from phthalaldehydic acid (1) the aromatic PG‐analogue, 7‐[2‐(3‐hydroxy‐(E)‐1‐octenyl)phenyl]heptanoic acid (9), was prepared in 7 steps in 49% overall yield. The cis‐substituted cyclohexane PG‐analogue, ethyl 7‐[cis‐2‐(3‐hydroxy‐(E)‐1‐octenyl)cyclohexyl]heptanoate (34), was obtained in 7 steps in 53% overall yield from the same starting material 1. The trans‐substituted cyclohexane PG‐analogue, ethyl 7‐[trans‐2‐(3‐hydroxy‐(E)‐1‐octenyl)cyclohexyl]heptanoate (20), was synthesized from methyl 9‐cyano‐(E)‐2‐nonenoate (12) in 8 steps in 34% yield.
The substitutional incorporation of Fe(III) and Cr(III) ions within gibbsite by homogeneous precipitation
Authors: van Dijk J. 
Published: September 2010

AbstractFe(III) and Cr(III) have been incorporated in gibbsite (∼ 1%) by oxidation of a Fe(III)‐triethanolamine complex with Cl2 and reduction of K2CrO4 with hydrazine at an appropriate rate, during the precipitation of gibbsite from an alkaline aluminate solution. The products show characteristic single ion ESR spectra.
Phosphite triesters of methyl α‐D‐ and methyl β‐D‐ribopyranoside
Authors: Bellaart A. C. , Buck H. M. , Leclercq P. A. , van de Ven L. J. M. 
Published: September 2010

AbstractThe phosphites of methyl α‐D‐ and methyl β‐D‐ribopyranoside were prepared from the corresponding methylglycosides according to the method of Stetter and Steinacker1. The mass spectra of the isomeric phosphites, which are markedly different, and the NMR spectral data are in agreement with the proposed structures.
Interaction between functional groups in low‐molecular‐weight polyfunctional compounds
Authors: van Treslong C. J. Bloys 
Published: September 2010

AbstractFrom experimental values of the ionization constants of low‐molecular‐weight poly‐functional acids and bases a consistent picture regarding the interaction between the functional groups, in both the uncharged and charged states, can be evaluated. Assuming simple additivity for both interaction effects, calculations on various series of homologous compounds result in uniform values for both effects.
Chemical shifts and substituent effects in the PMR spectra of substituted isoquinolines
Authors: Sanders Georgine M. , van Dijk M. , van Veldhuizen A. 
Published: September 2010

AbstractChemical shifts of H‐l, H‐3 or H‐4 are given for 19 mono‐ and 30 di‐substituted isoquinolines, carrying halogeno, amino, ethoxy or phenyl substituents in the pyridine nucleus. For the disubstituted isoquinolines, δ‐values calculated on the basis of additivity, agree with the experimental values.
On the reaction of 2‐, 3‐ and 4‐bromo(chloro)‐1,8‐naphthyridine with potassium amide in liquid ammonia
Authors: van der Plas H. C. , Woźniak M. , van Veldhuizen A. 
Published: September 2010

AbstractEvidence has been presented for the occurrence of 3,4‐didehydro‐1,8‐naphthyridine in the reaction of 3‐bromo(chloro)‐ and 4‐bromo(chloro)‐1,8‐naphthyridine with potassium amide in liquid ammonia. The addition ratio of the amide ion (ammonia) to C(3) and C(4) in the didehydro bond was found to be 43/57, which is nearly identical with that found in 3,4‐didehydroquinoline, 3,4‐didehydro‐1,7‐naphthyridine and 3,4‐didehydro‐1,6‐naphthyridine. It was calculated that 39% of the 4‐amino compound, obtained from the 4‐bromo‐1,8‐naphthyridine is formed by an SN(AE) process. In the reaction of 3‐chloro‐1,8‐naphthyridine with potassium amide, besides the 3‐amino and 4‐amino compounds, 2‐amino‐3‐ethynylpyridine and 3‐ethynyl‐2‐(formylamino)pyridine were obtained, indicating a fission of the bond between C(2) and C(3). The last mentioned compound is also formed in the reaction of 4‐chloro‐1,8‐naphthyridine. 1H‐NMR spectroscopy has shown that 3‐bromo(chloro)‐1,8‐naphthyridine forms with the amide ion a σ‐adduct at C(2); this adduct formation preceded the formation of the didehydro compound. 2‐Bromo(chloro)‐1,8‐naphthyridine gave exclusively 2‐amino‐1,8‐naphthyridine. Conclusive evidence was obtained that part of the 2‐amino compound was formed by a tele‐substitution SN(AE)tele involving the 7‐amino‐2‐chloro(bromo)‐7,8‐dihydro‐1,8‐naphthyridine (27% in the case of the 2‐bromo compound, 8% in the case of the 2‐chloro compound).
Carbohydrate separation by X‐zeolites. Cation and solvent effects
Authors: Wortel Th. M. , van Bekkum H. 
Published: September 2010

AbstractThe adsorption of fructose and glucose on X‐zeolites has been studied. The adsorption capacity and the selectivity of adsorption depend on the type of cation in the zeolite, the extent of cation exchange and the solvent used. Fructose and glucose can be conveniently separated by column chromatography using NaCaX as the stationary phase and eluting with aqueous methanol. This system also allows separation of other monosaccharides, of monosaccharides and disaccharides, and of monosaccharides and related alditols.
N‐Nitroso‐5‐methyl‐1,3‐oxazolidine identified as an impurity in a commercial cutting fluid
Authors: Stephany R. W. , Freudenthal J. , Schuller P. L. 
Published: September 2010

AbstractThe title N‐nitrosamine was detected in a mineral oil cutting fluid concentrate up to 30 mg per kg. Compound identification was performed by gaschromatography‐mass spectrometry and synthesis. A possible route of formation of the detected N‐nitrosamine starting from 1‐amino‐2‐propanol is suggested.
Crystal and molecular structure of N,N′‐[bis(tosylmethyl)]urea. Conformational preferences and non‐bonded interactions
Authors: Visser R. J. J. , Vos A. , Tel R. M. , Engberts J. B. F. N. 
Published: September 2010

AbstractThe room temperature crystal and molecular structure of the title compound have been determined by direct methods from diffractometer data. Crystals are monoclinic, a = 12.809(2). b = 9.182(7), c = 17.719(6) Å, β = 116.09(2)°, space group P21/c, Z = 4. The structure was refined by anisotropic least‐squares to R = 0.099 for 1944 independent reflections. The molecule resides in a conformation in which the tosyl rings face each other, so that there roughly is a mirror plane through the CO bond and perpendicular to the NCON plane.Each carbonyl oxygen atom is hydrogen bonded to both nitrogen‐hydrogen atoms of a neighbouring urea moiety. Potential energy calculations suggest that the conformational preferences are mainly caused by non‐bonded interactions as described by atom‐atom interaction functions of the Buckingham type.
Chemistry of 2H‐thiopyran and derivatives I. 2H‐ versus 6H‐proton abstraction from 2H‐thiopyran
Authors: Gräfing R. , Brandsma L. 
Published: September 2010

AbstractDepending on the nature of the base/solvent system deprotonation at carbon atoms 2 and 6 in 2H‐thiopyran 1 can be carried out specifically. Conversion of 6‐lithio‐2H‐thiopyran (4) into the charge‐delocalised species 2 takes place in the presence of diisopropylamine, probably via a process of proton donation and abstraction. Addition of hexamethylphosphoric triamide (HMPT) to the solution of 4 also gives rise to the formation of the thermodynamically more stable species 2.
Cationic heterocyclisation One‐step synthesis of condensed heterocyclics
Authors: Wijnberg J. B. P. A. , de Boer J. J. J. , Speckamp W. N. 
Published: September 2010

AbstractAcid treatment of N‐aryl‐5‐hydroxy‐2‐pyrrolidinones and their ethers obtained from N‐arylsuccinimides by means of NaBH4/H+ reduction leads to mixtures of dimeric coupling products which may give additional ring closure with the N‐aryl substituent.
Restricted rotations in configurational assignments: The Diels‐Alder adduct of 1,3,5‐cycloheptatriene and maleic anhydride
Authors: Verma Shiva Mohan , Singh M. Dhaneshwar 
Published: September 2010

AbstractThe configuration of the Diels‐Alder adduct of 1,3,5‐cycloheptatriene (CHT) and maleic anhydride has been investigated using 1H‐NMR spectroscopy. Evidence for the endo‐cis‐endo‐configuration and the tricyclo[3.2.2.02′4]nonane skeleton of the adduct has been provided by the 1H‐NMR spectra observed for the various derivatives of the adduct. While non‐planar conformations about the N‐N′ bond in N‐(diacylamino)imides of the adduct have been utilized in establishing the orientation of the anhydride ring, the bromination of the double bond of the adduct (exo‐cis‐addition) has demonstrated the configuration of the cyclopropane ring.
Inherently chiral olefins. Synthesis and resolution of 4‐(9‐fluorenylidene)‐1,2,3,4‐tetrahydrophenanthrene
Authors: Feringa Ben , Wynberg Hans 
Published: September 2010

AbstractThe reductive coupling of 4‐keto‐1,2,3,4‐tetrahydrophenanthrene with 9‐fluorenone and acetone is described. The inherently chiral 4‐(9‐fluorenylidene)‐1,2,3,4‐tetrahydrophenanthrene was resolved chromatographically and chiroptical properties are presented.
Synthesis of N,N‐phthaloyl‐L‐valine and N,N‐phthaloyl‐L‐isoleucine with N‐(ethoxycarbonyl)phthalimide
Authors: Adriaens P. , Meesschaert B. , Janssen G. , Dumon L. , Eyssen H. 
Published: September 2010

AbstractThe synthesis of N,N‐phthaloyl‐L‐valine and N,N‐phthaloyl‐L‐isoleucine with N‐(ethoxycarbonyl)phthalimide, using a modification of the method of Nefkens, Tesser and Nivard, is described. When aqueous solutions of the sodium salts of the amino acids are stirred at room temperature with a 10% excess of N‐(ethoxycarbonyl)phthalimide, dissolved in ethyl acetate, the main products formed are N‐[N‐(ethoxycarbonyl)phthalamoyl]‐L‐valine or N‐[N‐(ethoxycarbonyl)phthalamoyl]‐L‐isoleucine. The presence of these intermediates confirms the reaction mechanism proposed by Nefkens et al. Refluxing these compounds in toluene gives good yields of optically pure phthaloyl‐L‐valine and phthaloyl‐L‐isoleucine. From the synthesis of phthaloylvaline, N‐(ethoxycarbonyl)phthalamic acid and minor amounts of phthalic acid, valine and the phthalamic acid derivative from phthaloylvaline were identified as by‐products.
Addition and substitution reactions of hexahelicene: Bromination, nitration and acetylation
Authors: op den Brouw P. M. , Laarhoven W. H. 
Published: September 2010

AbstractBromine adds to hexahelicene at the C(5)‐C(6) and C(11)‐C(12) bond. The addition products eliminate hydrogen bromide on heating above 100°C, yielding mainly 5‐bromo‐ and 5,12‐dibromohexahelicene, respectively. The same elimination reactions occur on chromatography of the addition products over silica gel or alumina. In pyridine or triethylamine, however, bromine is eliminated.Bromination in the presence of iodine yields also the substitution products 5‐bromo‐ and 5,12‐dibromohexahelicene. Nitration and acetylation are less selective, but under sufficiently mild conditions 5‐ and 5,12‐substitution products can very well be obtained; in both cases an 8‐substituted hexahelicene can be isolated as a second product.Although several reactivity parameters (Nr, Fr and μr values) predict high reactivity towards electrophiles at C(5) the high selectivity of the aromatic substitutions could not be foreseen from Fr (and Nr) values, whereas μr values predict higher reactivity at C(3) than at C(8).
1H‐ and 13C‐NMR studies of σ‐adducts of 1,2,4‐triazine and some of its derivatives with amide ions and/or liquid ammonia
Authors: Rykowski A. , van der Plas H. C. , van Veldhuizen A. 
Published: September 2010

AbstractUnambiguous 1H‐ and 13C‐NMR spectroscopic data have been presented for the formation of σ‐adducts between a series of 1,2,4‐triazines and amide ions and/or liquid ammonia at C(5) of the 1,2,4‐triazine nucleus.
Photochemical radical chain dehalogenation of some simple organic halogen compounds
Authors: van Beek H. C. A. , van Der Stoep H. J. 
Published: September 2010

AbstractTetrachloromethane and hexachloroethane can be photoreduced with a high quantum yield in solutions of acetone and an alcohol. The reducing agent in this reaction is the ketyl radical, formed after hydrogen abstraction from the alcohol by the trichloromethyl radicals or pentachloroethyl radicals. The overall reaction is a radical chain process, in which the ketyl radicals and the trichloromethyl or pentachloroethyl radicals are the propagating species. Other polyhalogeno aliphatic compounds can be photoreduced in a similar fashion.
Biomimetic total synthesis of steroids II: Stereoselective synthesis of 7α‐methyl‐19‐norsteroids
Authors: Groen M. B. , Zeelen F. J. 
Published: September 2010

AbstractThe cationic cyclization of 3‐methyl‐2‐[6(m‐methoxyphenyl)‐5‐methyl‐(E)‐3‐hexenyl]‐2‐ cyclopentenol (4) was investigated. The major products were 1‐ and 3‐methoxy‐7α,17‐dimethyl‐1,3,5(10),13(17)‐gonatetraene (12 and 13a) indicating high asymmetric induction by the methyl substituent. Compound 13a was converted into DL‐7α‐methylestrone methyl ether (15a).
Derivatives of cis‐NPCl2(NSOCl)2 and (NPCl2)2NSOCl. Part VII. Isothiocyanato derivatives of (NPCl2)2NSOF, (NPCl2)2NSOPh and trans‐NPCl2(NSOPh)2
Authors: Klei E. , van de Grampel J. C. 
Published: September 2010

AbstractSome isothiocyanato derivatives of (NPCl2)2NSOF, (NPCl2)2NSOPh and trans‐NPCl2‐(NSOPh)2 are prepared by reaction of these compounds with KSCN. The fully substituted derivatives are white crystalline solids, whereas NPCl2NP(NCS)2NSOF is a colourless liquid at room temperature. The mono‐isothiocyanato derivatives NPCl2NPClNCSNSOF and NPCl2NPClNCSNSOPh consist of mixtures (∼ 1:1) of two isomers. It is shown that substitution by NCS groups proceeds via a geminal pathway. The compounds are characterized by spectroscopic methods.
Attempted syntheses of 9‐stibaanthracene and 10‐phenyl‐9‐stibaanthracene
Authors: Bickelhaupt F. , Lourens R. , Vermeer H. , Weustink R. J. M. 
Published: September 2010

AbstractAttempts were undertaken to prepare 9‐stibaanthracene (2c) and its 10‐phenyl derivative (3c). Both compounds proved to be too unstable for isolation; their possible occurrence as intermediates is discussed briefly.
C‐Nitroso compounds. Part XXXII. Reaction of α‐chloro nitroso compounds with alkyl substituted allenes. A route to cross‐conjugated aliphatic ketonitrones
Authors: Schenk C. , de Boer Th. J. 
Published: September 2010

AbstractReaction of α‐chloro nitroso compounds with tetramethylallene gives rise to the formation of hitherto unknown crystalline cross‐conjugated nitrone hydrochlorides 3, which can be converted into free nitrones 4 upon treatment with liquid ammonia. The reaction between 2‐chloro‐2‐nitrosoadamantane and 3‐phenyl‐1,2‐butadiene proceeds equally well, but with other α‐chloro nitroso compounds and with other alkylallenes only complicated mixtures are obtained, which contain the corresponding nitrone hydrochlorides as judged from hydrolysis to ketone and oxime 6.
Biomimetic total synthesis of steroids III: Stereoselective synthesis of 11α‐methyl‐19‐norsteroids
Authors: Groen M. B. , Zeelen F. J. 
Published: September 2010

AbstractThe synthesis and cationic cyclization of 2‐[6‐(3‐methoxyphenyl)‐2‐methyl‐(E)‐3‐hexenyl]‐3‐methyl‐2‐cyclopentenol (12) was investigated. The major cyclization products were 1‐ and 3‐methoxy‐11α,17‐dimethyl‐1,3,5(10),13(17)‐gonatetraene (14a and 15a) indicating a high degree of asymmetric induction by the pro‐C(11) chiral centre. Compound 15a was converted into DL‐11α‐methylestrone methyl ether (18).
Chemistry of electron‐rich conjugated polyenes III. Synthesis and acid hydrolysis of 2,2‐di‐ and 2,2,5‐trimethoxy‐5,6‐dihydropyrans
Authors: van Balen H. C. J. G. , Broekhuis A. A. , Scheeren J. W. , Nivard R. J. F. 
Published: September 2010

AbstractCarbonyl compounds, activated by electron‐withdrawing groups, add to 1,1‐dimethoxybutadiene (Ia), yielding 2,2‐dimethoxy‐5,6‐dihydropyrans (IIa). 1,1,4‐Trimethoxybutadiene (Ib) reacts in a similar way with suitably activated ketones, but gives[2 + 2]‐cycloadditions with activated aldehydes. The different behaviour is ascribed to steric factors. Acid hydrolysis of the 2,2‐dimethoxydihydropyrans yields α,β‐unsaturated esters and corresponding lactones, or dienyl esters depending on the reaction conditions used.1,1‐Dimethoxy‐3‐(trimethylsilyloxy)butadiene (Ic) yields Diels‐Alder adducts even with non‐activated carbonyl compounds, when zinc chloride is used as a catalyst. The products can be converted into dihydro‐γ‐pyrones by treatment with protic solvents (e.g. methanol).
Petits cycles à liaison germanium‐azote: Synthèse et réactivité de germa‐2 azolidines, germa‐2 azétidines, germa‐2 aziridines. Caractérisation de germa‐imines: Nouveaux intermédiaires à germanium π‐lié
Authors: Rivière‐Baudet M. , Rivière P. , Satgé J. , Lacrampe G. 
Published: September 2010

AbstractGermylated 3‐, 4‐ or 5‐membered heterocycles containing a Ge‐N bond are synthetized by direct aminolysis (followed by dehydrochlorination) or by action of amino dilithium compounds on germylated dichlorides of the general structure magnified image. The preparations of these new dichlorides are also described.2‐Germaazolidines are thermally stable. 2‐Germaazétidines decompose at moderate temperature, through a β‐elimination process, to give germa‐imine magnified image and alkene. 2‐Germaaziridines, likely in equilibrium with an open zwitter ionic form, readily decompose through an α‐elimination process, to lead to the corresponding germylene and imine.The reactivity of these heterocycles has been considered from specific reactions of the Ge‐N bond: cleavage by protic species, LiAlH4 reduction or addition on insaturated compounds (CS2, PhNCO), the last reaction leading to ring expansion.
N,N‐Dimethyl‐2,4,6‐tri‐tert‐butylaniline: Preparation and properties
Authors: Harff G. A. , Sinnema A. , Wepster B. M. 
Published: September 2010

AbstractThe title compound, 3, is prepared in high yield starting from 2,4,6‐tri‐tert‐butylaniline, 1. Reaction with formaldehyde provides N‐methylene‐2,4,6‐tri‐tert‐butylaniline, 5; N‐methylation then gives the immonium salt 6 which is reduced to 3. The thermodynamic dissociation constant in 50% ethanol at 25°C, pKa* = ‐ 1.42, is 5.6 pK units lower than that of N,N‐dimethylaniline. The effects contributing to this difference are evaluated. Protonated 3 is found to have a rotational barrier around CarN, of 63.6 kJ/mol, which is about 4.5 kJ/mol lower than that found for protonated N,N‐dimethyl‐2,4,6‐trimethylaniline.
Investigations on sterols. 40. The synthesis of ring D substituted 9β,10α‐steroids
Authors: Halkes S. J. , van Etten A. B. , Postmus T. L. , Bontekoe J. S. , Rappoldt M. P. 
Published: September 2010

AbstractThe retro configuration (9β,10α) was introduced into pregnane derivatives containing substituents at C(16) and/or C(17) by irradiation of a suitable 5,7‐diene. In this way the title compounds became much more accessible than by the introduction of ring D substituents into 20‐ketoretro‐steroids.
Conductivity and relaxation effect of alkali polymethacrylates in alkali bromide solutions
Authors: van der Drift W. P. J. T. , Overbeek J. Th. G. 
Published: September 2010

AbstractThe electric conductivity of alkali polymethacrylates in aqueous solutions of alkali bromides with concentrations varying from 0.001 mol/l to 0.1 mol/l was measured. From a comparison of the conductivities of different alkali salts (Li, Na, K) the relaxation correction on the mobility of the polyion and of the counterions was estimated by use of the method of Möller et al. This correction lowered the mobilities by a factor of about one half. Relaxation effects of similar magnitude have been derived from the dispersion of the conductivity of other linear polyelectrolytes in the megacycle range.