bluuebunny/crossref_metadata_2025 huggingface dataset:
The chemistry of 3‐ketotetrahydrofurans II: The cyclization of 2‐alkoxyethyl diazomethyl ketones
Authors: Weiland J. H. Sperna
Published: September 2010

Ring closure of 2‐alkoxyethyl diazomethyl ketones (VII) under the influence of a catalytic amount of hydrochloric acid gives 3‐ketotetrahydrofuran (VIII). The yields obtained in this reaction are greatly influenced by the choice of the alkoxy group. 3‐Ketotetrahydrothiophen (XX) is prepared from 2‐tert.butylthioethyl diazomethyl ketone (XIXa) by the same procedure.
Determination of molecular weights by means of thermoelectric vapour phase osmometry
Authors: van Dam J.
Published: September 2010

A description is given of a thermoelectric vapour phase osmometer for the determination of molecular weights or, more generally, of the osmotic activity of solutions. In this instrument the vapour pressure difference between a solution of the substance under investigation and the pure solvent is converted into a temperature difference between the junctions of one or more thermocouples. From a detailed consideration of the heat and mass transfer in the steady state, the temperature difference can be calculated. The theory is fully corroborated by some experiments on solutions in benzene and water of substances of known molecular weights. Finally, an application of the method to the determination of the molecular weights of some polystyrene samples, ranging between 3 000 and 14000, is discussed. The upper limit lies around 30 000 with an accuracy of about 10%.
Synthèse et propriestes physiques des tétraalcoylméthanes en C17
Authors: Maire Jean‐Claude , Desgrandchamps Guy
Published: September 2010

La synthèse des tétraalcoylméthanes en C17 a été effectuée suivant une méthode basée sur une synthèse de Knoevenaegel. Les courbes viscositè‐température des hydrocarbures obtenus ont été tracées entre 20 et 120° et l'allure des courbes confrontée avec les formules proposées par: Andrade et Sheppard, Walther, Hugel et Watermann. Entre deux températures dont la différence est inférieure α 40°, l'écart relatif entre les valeurs mesurées et les valeurs calculées par interpolation α l'aide des trois dernières formules n'excède pas un pourcent.
Untersuchungen über N‐Oxyde des 2‐Dimethylaminopyridins: (die Nitrierung des N1‐oxyde des 2‐Dimethylaminopyridins)
Authors: Wieczorek J. S. , Płazek E.
Published: September 2010

Bei der Einwirkung von Peressigsäure auf 2‐Dimethylaminopyridin entsteht ein N‐Oxyd welches von dem N1‐Oxyd, das aus dem N‐Oxyd des 2‐Chloropyridin durch Aminolyse erhalten worden ist, verschieden ist; das Sauerstoffatom in der neuen Verbindung befindet sich offenbar am Stickstoff der Dimethylaminogruppe (N2‐Oxyd). Bei der Nitrierung des bekannten N1‐Oxydes entsteht ein N1‐Oxyd des 2‐Dimethylamino‐5‐nitropyridins. Mehrere Derivate der letzten Verbindung, darunter das Reduktionsprodukt: das N1‐Oxyd des 5‐Amino‐2‐dimethylamino‐pyridins sind dargestellt worden.
Phosphatidic acids and derivatives XII: Synthesis of bis‐β‐glycerophosphatidic acids starting from αγ‐diglycerides with one or two saturated component acids
Authors: van Gijzen J. , Hoefnagel M. A. , Verkade P. E.
Published: September 2010

A method is described for the preparation of bis‐β‐glycerophosphatidic acids starting from αγ‐diglycerides with one or two saturated component acids.
Structure of 2,4,6‐trialkylsubstituted 1,3,5‐trioxans
Authors: Barón Máximo , Hollis Donald P.
Published: September 2010

The structure of several 2,4,6‐trisubstituted 1,3,5‐trioxans has been studied by N.M.R. and the dipole moment of α‐parabutylchloral has been measured in solution. All compounds were found to be in the chair conformation.
On the ozonolysis of indane and tetralin as well as some dimethyl homologues in connection with the reactivity of the bonds in the ring system: (with reference to the so‐called Mills‐Nixon effect)
Authors: de Jong F. P. K. , Wibaut J. P.
Published: September 2010

In the ozonolysis of 4,7‐dimethylindane the aliphatic dicarbonyl compounds methylglyoxal and glyoxal are formed in a combined yield of 0.1 mol of dicarbonyl compound per mol of dimethylindane. The molecular ratio glyoxal: methylglyoxal is 1.57: 1.

In the ozonolysis of 5,6‐dimethylindane the aliphatic dicarbonyl compounds methylglyoxal and dimethylglyoxal (diacetyl) are formed in a combined yield of 0.05 mol per mol of dimethylindane. The molecular ratio diacetyl: methylglyoxal is 3.5: 1.

From the above it follows that each of the six carbon‐carbon bonds of the aromatic six‐membered ring in 4,7‐ and 5,6‐dimethylindane respectively can react with ozone. There is no question of a “fixation” of the double bonds in the aromatic six‐membered ring. From the molecular proportion of the dicarbonyl compounds it follows that during the action of ozone on 4,7‐ and 5,6‐dimethylindane respectively there is a marked preference for the attack of the common carbon‐carbon bond of the ring system. This common carbon‐carbon bond displays towards ozone a stronger double‐bond character than do the adjacent carbon‐carbon bonds in the aromatic ring. This result is contrary to the theory ofMillsandNixon, but is qualitatively in agreement with the calculations ofLonguett‐HigginsandCoulson.

In the ozonolysis of 5,8‐dimethyltetralin the aliphatic dicarbonyl compounds glyoxal and methylglyoxal are formed in a combined yield of 0.07 mol per mol of dimethyltetralin. The molecular ratio methylglyoxal: glyoxal is about 3: 1. In the ozonolysis of 6,7‐dimethyltetralin the aliphatic dicarbonyl compounds methylglyoxal and dimethylglyoxal are formed in a combined yield of 0.09 mol per mol of dimethyltetralin. The molecular ratio methylglyoxal: dimethylglyoxal is 1.1: 1.

From these findings it follows that each of the six carbon‐carbon bonds of the aromatic six‐membered ring in 5,8‐ or 6,7‐dimethyltetralin can react with ozone.

There is no marked preference for the attack of the common carbon‐carbon bond, as compared with the attack of the adjacent carbon‐carbon bonds in the aromatic six‐membered ring. This result is contrary to the theory ofMillsandNixon.

To check the analytic method used by us, we examined the ozonolysis of p‐xylene and of 1,2,4,5‐tetramethylbenzene (durene).

In the ozonolysis of p‐xylene, methylglyoxal and glyoxal are expected to be formed in the molecular ratio 2: 1; the proportion found was 2.15: 1.

In the ozonolysis of durene, methylglyoxal and dimethylglyoxal are expected to be formed in the molecular ratio 2: 1; the proportion found was 1.93: 1.
Chemistry of acetylenic ethers 73: Alkali amide cleavage of allenyl thioethers
Authors: Montijn P. P. , Brandsma L.
Published: September 2010

Allenyl thioethers of the type CH3CHC (R = alkyl) have been converted in very good yield into 1,3‐enynes HCC‐CHCH‐R (IV) on treatment with two equivalents of alkali amide in liquid ammonia, followed by hydrolysis of the reaction mixture.
The alkylation of phenol with isobutene
Authors: de Jong J. I.
Published: September 2010

Some aspects of the alkylation of phenol with isobutene using small quantities of sulfuric acid as a catalyst are discussed. It is shown that initially ortho and para substitution take place to roughly the same extent. In the course of the reaction the isomer distribution changes in favour of the para isomer, the alkylation being reversible. Equilibrium constants were determined in the temperature range of 50‐125°.
Oxidative rearrangement of trismethylene‐trinitrobenzene: Nucleophilic aromatic addition VI
Authors: de Boer Th. J. , van Velzen J. C.
Published: September 2010

Trismethylene‐trinitrobenzene I undergoes ring contraction when oxidised under mild, alkaline conditions to give stereoisomeric hydroxy‐acids IVa and IVb. Both isomers yield the same cyclic ketone V when oxidatively decarboxylated. This ketone can be subjected to a similar rearrangement as I by successive treatment with selenium dioxide and copper sulphate in pyridine, resulting in another pair of stereoisomeric hydroxy‐acids, VIIIa and VIIIb. Both these isomers are oxidatively decarboxylated to the cyclic ketone IX. V and IX, both α‐nitro‐ketones, undergo ring fission with alkali. The resulting carboxylic acids are identical with acids obtained previously from I by different routes.
Degradative iodination of thioanisole
Authors: van der Veen J. , Stevens W.
Published: September 2010

Degradative halogenation of thioanisole by iodine at temperatures between 100° and 150° was found to produce diphenyl sulfide, diphenyl disulfide, thianthrene and trimethylsulfonium iodide together with small amounts of hydrogen sulfide, hydrogen iodide, methyl iodide and dimethyl sulfide. Diphenyl sulfide and thianthrene did not react with iodine under analogous conditions. Diphenyl disulfide, on the other hand, reacted with iodine to yield diphenyl sulfide, thianthrene and hydrogen sulfide.

A thin‐layer chromatographic method was developed in order to identify thioanisole, diphenyl sulfide, diphenyl disulfide and thianthrene in the reaction mixtures obtained.
Aromatic sulfonation X: Determination of the kinetic isotope effect of hydrogen in the sulfonation and sulfonylation of benzene remarks on hydrogen exchange between benzene and benzenesulfonic acid
Authors: Cerfontain H. , Hofman H. J. , Telder A.
Published: September 2010

The kinetic isotope effect of hydrogen for sulfonation with sulfur trioxide has been determined at 25.0° in a competitive study, using hexadeuterated and ordinary benzene, askH/kD= 1.14 ± 0.06. Hydrogen exchange between benzene and benzenesulfonic acid is relativelys slow under these conditions and does not interfere with the determination of the isotope effect.

Diphenylsulfone was found as a by‐product in the sulfonation reaction. The kinetic isotope effect for the sulfonylation of benzene at 25.0° was found to bekH/kD= 0.86 ± 0.06.

It is proposed that the hydrogen exchange between benzene and anhydrous benzenesulfonic acid proceeds according to a SE‐2 type of mechanism.
Investigations on sterols XXII. The synthesis of 4‐H3‐9β,10α‐progesterone and 4‐H3‐6‐dehydro‐9β,10α‐progesterone
Authors: van Kamp H. , Westerhof P. , Niewind H.
Published: September 2010

The synthesis is described of 9β,10α‐progesterone and of 6‐dehydro‐9β,10α‐progesterone and of 6‐dehydro–β,10α‐progesterone both tritiated at C4.
Studies on vitamin D and related compounds XVII: The photo‐formation of lumisterol
Authors: Sanders Georgine M. , Havinga E.
Published: September 2010

A further investigation has been made of the pathway of the photo‐formation of lumisterol, which had remained doubtful after the previous analyses of irradiation mixtures, in which lumisterol was determined indirectly3. Experiments using tachysterol3‐7‐3H reveal that lumisterol is not formed directly from tachysterol to a significant extent. Thin layer chromatograms of mixtures obtained after various times of irradiation starting with solutions of pre‐calciferol3 and tachysterol3 indicate the direct formation of lumisterol3 from precalciferol3. The modified scheme of interrelationships between pro‐ and pre‐vitamin D, lumisterol and tachysterol is essentially the one originally postulated by Velluz, Amiard and Goffinet11. The question whether ergosterol and tachysterol yield other photo‐products besides precalciferol remains to be investigated.
Note on the isolation of β‐hydroxypalmitic acid from the extracellular lipids of: Rhodotorula Glutinis
Authors: van Ammers M. , Deinema Maria H. , Landheer C. A. , van Rooyen Margaretha H. M.
Published: September 2010

From the extracellular lipids produced by Rhodotorula Glutinis, β‐hydroxy‐palmitic acid was isolated. The structure of this acid was established by NMR and confirmed by synthesis.
The interaction of chloranil with aliphatic amines
Authors: Foster R.
Published: September 2010

Although substitution of chlorine usually occurs in the interaction of chloranil with aliphatic amines, solutions of chloranil in pure triethylamine yield a product which appears to be a salt, the anion of which is the free radical semiquinone ion derived from chloranil. In acetone solution this salt decomposes to yield 2,3,5‐trichloro‐6‐(2′‐diethylaminovinyl)‐p‐benzoquinone.
The η‐ and ε‐phase of the system copper‐silicon as solid reactants in the synthesis of dimethyldichlorosilane
Authors: Kolster B. H. , Vlugter J. C. , Voorhoeve R. J. H.
Published: September 2010

The investigation was performed partly at the Laboratory for Physical Chemistry of the solid state.

To investigate the actual form of the copper catalysing the direct synthesis of methylchlorosilanes, intermetallic compounds of silicon and copper are used as contact masses. Apparently copper must be present as an intermetallic compound with silicon in order to yield selectively dimethyldichlorosilane.

It appears that the selectivity of the direct synthesis can be maintained as long as free silicon is available to fill up the silicon sites in the intermetallic compound, which are emptied due to the reaction with methyl chloride.
Vapour pressure of selenium trioxide
Authors: Mijlhoff F. C. , Block R.
Published: September 2010

The vapour pressure of solid and liquid SeO3 was measured in the temperature range between 80°C and 120°C. Measurements are easily affected by the presence of residual SO3. The triple point is situated at 120.9°C and 5.5 mm Hg. The plot of log p against 1/T shows that the heat of vaporisation depends greatly on temperature. Sublimation pressure data can be explained in terms of a tetramer‐monomer dissociation in the gaseous phase. Calculated sublimation and dissociation enthalpies are 9.0 and 119 kcal/mole (SeO3)4.
Condensation of tri‐n‐propylbromogermane with propylene oxide
Authors: Pike R. M. , Lavigne A. A.
Published: September 2010

The rate of reaction of tri‐n‐propylbromogermane with propylene oxide has been measured under a variety of conditions. The effect on the reaction rate of temperature, concentration of reacting species, and the observed second‐order kinetics indicate a bimolecular type mechanism. The reaction offers a route to the synthesis of 2‐halo‐1‐hydroxy substituted alkanes.
The radical induced oxidation of acetaldehyde
Authors: Cerfontain H.
Published: September 2010

The radical induced oxidation of acetaldehyde in the photo‐oxidation of azoethane was studied at 28°, 118° and 152°. In most experiments the acetaldehyde built up was substantially less than 0.8 mm, the observed limiting value at high conversion. Major products in the radical induced oxidation of acetaldehyde are carbon dioxide and methanol; minor products are carbon monoxide and (per)acetic acid. Formaldehyde was positively identified as a reaction product. It is proposed that the formation of the reaction products proceeds via the acetyl radical:

CH3CHO + RCH2O· → CH3CO· + RCH2OH [8]

CH3CO· → ·CH3 + CO [9]

CH3CO· + O2 → CH3O· + CO2 [11]

CH3CO· + O2 → CH3CO3· [12]

CH3CO3· + AH → CH3CO3H + A· [16]

where AH stands for acetaldehyde and azoethane. The methoxy radicals will form methanol and formaldehyde.

Reaction [11] does not necessarily proceed in one step. At 28° k9/k11 = (4±2) · 1013 molec · cm −3.
Reactions of aliphatic halides with solutions of alkali metals in liquid ammonia IV. Experiments with optically active 1‐phenylethyl halides
Authors: Verkade P. E. , de Vries K. S. , Wepster B. M.
Published: September 2010

Optically active 1‐phenylethyl chloride or bromide when treated with a solution of lithium, sodium, or potassium in liquid ammonia yields optically active 2,3‐diphenylbutane. It is concluded that the formation of the “biaralkyl” proceeds via carbanions.

The absolute configurations of (+)‐ and (‐)‐2,3‐diphenylbutane are deduced.
Autoxidation of cyclohexanecarboxylic Acid‐l‐14C
Authors: Bigot J. A. , Duynstee E. F. J. , Hennekens J. L. J. P.
Published: September 2010

Oxidation of cyclohexanecarboxylic acid‐1‐14C by molecular oxygen at 205°C in the presence of cupric salt of cyclohexanecarboxylic acid and magnesium oxide yielded nearly equal amounts of cyclohexanone and cyclohexene. When cupric salt and magnesium oxide were omitted, only cyclohexanone was obtained. In both cases the label distribution in the cyclohexanone was determined. This showed that in the presence of cupric salt and magnesium oxide and at a temperature of about 205°C, cyclohexanone formation comes about by attachment of oxygen to either the tertiary carbon atom (54%) or to one of the neighbouring secondary carbon atoms (44%) of the cyclohexanecarboxylic acid molecule. In the absence of cupric salt and magnesium oxide over 90% of the cyclohexanone is formed by attachment of oxygen to the tertiary carbon atom of the cyclohexanecarboxylic acid.

When the oxidation is carried out in the presence of cupric salt and magnesium oxide, but at a lower temperature (165°C), cyclohexanone formation is very slow; the label distribution indicated formation through oxidative attack at the tertiary carbon atom only.

The fact that at 205°C and in the presence of cupric salt and magnesium oxide, oxidative attack at the β‐carbon atoms of cyclohexanecarboxylic acid takes place, is tentatively explained by assuming the formation of the 2‐carboxycyclohexyl radical (II) from the cupric salt of cyclohexanecarboxylic acid.
Non‐hydrolyzable synthetic analogs of phosphatidic acids
Authors: Rosenthal Arthur F. , Kosolapoff Gennady M. , Geyer Robert P.
Published: September 2010

Diether‐phosphonate analogs of phosphatidic acids of the type ROCH2‐CH(OR′)CH2P(O)(OH)2(RC2H5,R′CH3;RC18H37,R′C16H33;RC18H37,R′CH3) have been prepared by reaction of the corresponding iodides with triethyl phosphite, followed by hydrolysis. The iodides were prepared in one step from the allyl alkyl ether, alcohol, iodine, and zinc oxide. It was found that a reagent recently described for the detection of phosphatides on thin‐layer chromatograms also detects many but not all phosphonic acids and esters. The synthesis of propargyl octadecyl ether and of barium ethyl 2‐benzyloxyethylphosphonate is also described.
Chemistry of acetylenic ethers: 76 Preparation of compounds with a 1,3‐enyne system
Authors: Montijn P. P. , Schmidt H. M. , van Boom J. H. , Bos H. J. T. , Brandsma L. , Arens J. F.
Published: September 2010

Ethers with the systems , CH3CCCH(OR)2, CH3CCCH(OR)3 or ‐CH2‐CH2‐CCOR undergo an elimination of ROH [R = alkyl, 2‐alkynyl (‐CH2CC‐R′) phenyl, or 2‐tetrahydropyranyl] with formation of 1,3‐enyne derivatives, , on treatment with alkali amides in liquid ammonia.

The cyclic ethers: and are isomerized under these conditions to the 1,3‐enyne carbinols HCC‐CHC(CH3)CH2OH and HCC‐CHCH(CH2)4OH.
Saturated five‐membered heterocyclics, III.: Conversion of 1,3,4‐oxadiazolidines into 1,2,4‐triazolidines
Authors: Zwanenburg B. , Weening W. E. , Strating J.
Published: September 2010

2,3,4,5‐Alkyl substituted 1,3,4‐oxadiazolidines have been converted into 1,2,3,4,5‐substituted 1,2,4‐triazolidines by reaction with a primary amine and a trace of acid as a catalyst. 2,3‐Diethyl‐1,3‐oxazolidine gave on treatment with n‐butylamine and acid, instead of the corresponding imidazolidine, ring cleavage to N‐ethylaminoethanol and the Schiff base VII. The mechanism of these aminolyses is discussed.
The formation of 2,2‐di(4‐hydroxyphenyl)propane (bisphenol‐a) from phenol and acetone
Authors: de Jong J. I. , Dethmers F. H. D.
Published: September 2010

The addition of phenol to acetone appeared to be the rate‐determining step in the formation of bisphenol‐A in the presence of sulfuric acid. The kinetic picture was further supplemented by the synthesis of two possible intermediates and by measuring their equilibrium.
The synthesis of [6,7‐T]‐tropine
Authors: Hespe W. , Klopper W. J. F. , Nauta W. Th.
Published: September 2010

The synthesis of [6,7‐T]‐tropine has been effected by reacting 2,5‐dimethoxy‐2,5‐dihydrofuran with tritium gas and subsequently hydrolysing the product to [2,3‐T]‐succindialdehyde. A Robinson‐Schöpf reaction afforded [6,7‐T]‐tropinone, which was finally reduced with the aid of Raney nickel and hydrogen.
Mass spectrometry of nitro compounds: Part I: Mass spectra of α‐, β‐ and γ‐deuterated 1‐nitropropane
Authors: Nibbering N. M. M. , de Boer Th. J. , Hofman H. J.
Published: September 2010

A fragmentation pattern is suggested for 1‐nitropropane by comparing its mass spectrum with that of its α‐, β‐ and γ‐deuterated analogues.
Some aspects of the interaction of β‐rays with matter
Authors: de Ligny C. L. , Levering T. , de Hoyer H.
Published: September 2010

The backscattering and absorption of β‐rays by compounds have been measured and interpreted on the basis of elemental reflecting and stopping powers. A straightforward method has been devised for the determination of the elemental stopping powers. The elemental reflecting powers have been compared with the backscattering from elements and appear to be in good agreement. A simple relationship has been shown to exist between the elemental reflecting and stopping powers.
A simple method for the preparation of some methylphenylsulfonium nitrates
Authors: van der Veen J.
Published: September 2010

A simple method for the preparation of dimethylphenyl‐, dimethyl‐p‐chlorophenyl‐ and methyldiphenylsulfonium nitrate is described.

By condensing equimolar amounts of mercuric iodide and a phenyl sulfide with methyl iodide a sulfonium triiodomercurate is formed. The triiodomercurate is converted into the nitrate by using an anion exchange resin.
The influence of non‐planarity in styrene and stilbene derivatives VI: Dipole moments and conformations of cis‐ and trans‐benzal ketones
Authors: Kronenberg M. E. , Havinga E.
Published: September 2010

Open chain α,β‐unsaturated ketones in solution show rotational isomerism. The infrared spectra of cis‐benzal ketones indicate that one conformation is predominant. To obtain more insight into the nature of this conformation the dipole moments of a number of cis‐ and trans‐benzal ketones were determined. The data suggest that in the cis‐isomer the carbonyl group is considerably twisted out of the plane of the double bond.
Selective alkylation of chelated hydroxyls in condensed benzopyrones ‐ Part II
Authors: Puranik Gurubasav S. , Rajagopal S.
Published: September 2010

Selective alkylation of 1 or 8 hydroxyl as 1,3‐dihydroxy‐ or 3,8‐dihydroxyxanthone is recorded.
The copper‐catalysed oxidation of unsaturated carbonyl compounds Part III: Oxidation of α,β‐ and β,γ‐unsaturated aldehydes and ketones by oxygen in the presence of cupric complexes
Authors: Volger H. C. , Brackman W. , Lemmers J. W. F. M.
Published: September 2010

Unsaturated (α,β‐ and β,γ‐) aldehydes and ketones, capable of forming a conjugated dienol can be oxidized under mild reaction conditions in the presence of catalytic amounts of cupric‐amine complexes in alkaline methanolic solution.

Specific oxidation in the γ‐position is thought to occur with formation of a γ‐hydroperoxy α,β‐unsaturated carbonyl compound as a primary intermediate. The decomposition products of the γ‐hydroperoxide depend upon the number of hydrogen atoms attached to the γ‐carbon atom. A hydroperoxide group attached to a primary carbon atom is converted into an aldehyde function; likewise a secondary and a tertiary γ‐carbon atom lead to a keto and an alcohol function, respectively.

The alcohols can be isolated as such, whereas products containing an aldehyde and a keto function form either cyclization products like unsaturated lactones, polyacetals or cyclic ethers or are cleft into esters and aldehydes.

The mechanism of the oxidation reaction is discussed briefly.
The oxidative coupling of aromatic compounds with palladium salts
Authors: van Helden R. , Verberg G.
Published: September 2010

Reaction of benzene, palladium chloride and sodium acetate in acetic acid solvent produces biphenyl in a high yield. In the absence of sodium acetate no reaction occurs. The reaction is first‐order with respect to benzene and PdCl2. With monosubstituted benzenes in general a mixture of isomeric biphenyls (X‐C6H4‐C6H4‐X,X = alkyl, aryl, OR, Cl, COOR) is obtained. The substitution pattern corresponds with that observed in electrophilic aromatic substitution. The substituents exert a weak polar effect: electron‐donating groups increase the rate, while the opposite holds for electron‐attracting groups.

With disubstituted benzenes steric effects play an important role. From o‐xylene 3,4,3′,4′‐ and 2,3,3′,4′‐tetramethylbiphenyl have been obtained as the only products in a molar ratio of 2.7 : 1.

The results are most satisfactorily described by a mechanism involving complex formation between the aromatic compound and PdCl2 as the rate‐determining step. The complex formed is assumed to yield a π‐cyclohexadienyl‐PdCl complex by a fast reaction with acetate anions. The complex formed, being unstable, decomposes to yield biphenyl and palladium metal.
Synthesis of α‐esters of N‐acylaspartic acid
Authors: Nefkens G. H. L. , Nivard R. J. F.
Published: September 2010

Several pure α‐esters of N‐benzyloxycarbonyl‐l‐aspartic acid have been obtained in high yields by esterification of N‐benzyloxycarbonyl‐L‐aspargine, followed by deamidation with nitrosonium hydrogen sulfate (NO · HSO4) in glacial acetic acid.
Hydroperoxides of partially reduced quinoxalines, pteridines and (iso)alloxazines: Intermediates in oxidation processes
Authors: Mager H. I. X. , Berends W.
Published: September 2010

Transient peroxides have now been found in the oxidation of condensed pyrazines. Tetrahydropteridines and dihydro(iso)alloxazines proved to have a catalytic effect on the nonenzymatic oxidation of other compounds. This could be explained by regarding the partially reduced condensed pyrazines as acceptors for molecular oxygen. A general structure has been proposed for hydroperoxides occurring as key‐intermediates. The new theory may provide a more complete explanation for some enzymatic oxidation proccesses like the enzymatic hydroxylation of phenylalanine to tyrosine.
The complete configuration of sedridine and of pelletierine
Authors: Beyerman H. C. , Maat L. , van Veen A. , Zweistra A. , von Philipsborn W.
Published: September 2010

(+)‐Sedridine fromSedum acreL. is shown to be (2S)‐1‐[(2′S)‐2′‐piperidyl]‐propan‐2‐ol.

Oxidation of unnatural (‐)‐sedridine yieldedD‐pipecolic acid, from which follows the absolute configuration of the piperidine asymmetric centre. Oxidation of unnatural (+)‐pelletierine sulfate gaveL‐pipecolic acid.

This also confirms a previous deduction of the absolute configuration of (‐)‐pelletierine fromPunica granatumL.; this is R‐1‐(2‐piperidyl)propan‐2‐one.

Racemic sedridine and allosedridine were condensed withp‐substituted benzaldehydes to 1‐(4‐substituted‐phenyl)‐3‐methylhexahydro‐1H,3H‐pyrido‐[1,2‐c]oxazines. The relative configurations followed from conformational analysis and proton magnetic resonance spectra: sedridine isthreoidand allosedridine iserythroid.
The phase diagram K2Wo4 ‐ Wo3
Authors: Gelsing R. J. H. , Stein H. N. , Stevels J. M.
Published: September 2010

The phase diagram K2WO4‐WO3 in the vicinity of the eutectic point is presented and X‐ray powder diffraction data of the solid compounds involved are tabulated. In addition to the stable compounds K2WO4, K2O · 2WO3, K2O · 3WO3 and K2O · 4WO3, two metastable compounds of as yet unknown composition may be formed.
Photoconductivity of crystals of anthracene doped with tetracene and acridine
Authors: Mulder B. J. , de Jonge J.
Published: September 2010

A study was made of the photoconductivity of anthracene crystals containing small amounts of tetracene and acridine in the crystal lattice and with aqueous solutions as the electrode material. Doping of anthracene with tetracene markedly reduced the photoconductivity but increased the variation of the photocurrent with the wavelength of the exciting light. The photoconductivity spectrum of heavily doped crystals accurately duplicated the absorption spectrum of anthracene. The theory according to which charge carriers in anthracene are generated only at the positive crystal‐water interface and the role of tetracene as a trap for excitation energy in anthracene can adequately explain the effects of tetracene on the photoconductivity. The effects of acridine on the photoconductivity of anthracene were opposite to those of tetracene. In order to understand the latter results another or an additional mechanism for the generation of charge carriers must be assumed to exist in the crystals doped with acridine.
The influence of sugars on the U.V. absorption spectrum of proteins
Authors: Berrens L. , Bleumink E.
Published: September 2010

N‐Glycosidic coupling of aldoses and the free amino groups of protein is accompanied by profound modification of the ultraviolet absorption spectrum of the protein partner in the Maillard reaction. The increased extinction coefficient at 250 mμ of protein‐carbohydrate complexes incorporating sites of N‐glycosidic linkage is largely attributable to effects of denaturation, while absorbancy changes at 325 and 350 mμ are accounted for by side reactions involving the sugar partner only. Specifically, the Maillard reaction between protein and sugar results in the formation of a chromophor at the site of coupling absorbing at 305 mμ. The identification of this chromophor as the 1,2‐enol form of an N‐substituted 1‐amino‐1‐deoxy‐2‐ketose is substantiated by studies of ultraviolet absorption in model systems containing low‐molecular weight primary amines and aldoses.
Studies in homogeneous catalysis.: Radicals of the \documentclass{article}\pagestyle{empty}\begin{document}\[{\rm R}_{\rm 2}{\rm NO}^{-\bullet}\]\end{document} type as catalysts for the oxidation of methanol by cupric complexes and as promoters for various oxidations catalysed by copper
Authors: Brackman W. , Gaasbeek C. J.
Published: September 2010

The stable radical di‐tert‐butyl nitroxide is found to catalyse various oxidation reactions effected by cupric complexes, and to promote various oxidations with oxygen catalysed by copper complexes. Examples of its activity are found in the formation of hydrogen cyanide from methanol, ammonia and oxygen, the synthesis of nitriles from aldehydes, ammonia and oxygen, and various catalytic oxidations of methanol to formaldehyde.

The kinetics and mechanism of the oxidation of methanol by cupric‐phenanthroline, catalysed by di‐tert‐butyl nitroxide, have been studied in detail. The essential step in this reaction appears to be a simultaneous hydrogen abstraction (by the nitroxide radical) and electron abstraction (by the cupric ion) from coordinated methanol. The activation of C‐H bonds with respect to hydrogen abstraction in methanol and other compounds coordinated to cupric ions is discussed.

The reactive cupric complexes are coordinatively unsaturated with respect to phenanthroline. The likewise unsaturated cuprous complexes formed during the oxidation regenerate the reactive cupric complexes by a fast electrontransfer reaction. This reaction gives rise to the peculiar phenomenon that the reaction rate is not a single‐valued function of the concentration of the starting‐materials, but is co‐determined by the history of the system.
Aromatic sulfonation XV: Isomerization and dealkylation of t‐butylbenzenesulfonic acids in aqueous sulfuric acid
Authors: Cerfontain H. , Arends J. M.
Published: September 2010

The kinetics of the isomerization of p‐ and m‐t‐butylbenzenesulfonic acid have been studied in 74.0 wt‐% sulfuric acid at elevated temperatures. The isomerization is accompanied by dealkylation. Evidence was obtained that the formation of benzenesulfonic acid from p‐t‐butylbenzenesulfonic acid proceeds mainly by a three‐step process, viz., desulfonation, dealkylation and sulfonation of the benzene produced. With m‐t‐butylbenzenesulfonic acid, however, there is an indication of additional dealkylation of the sulfonic acid itself. Desulfonation rate constants were calculated. The activation energies for desulfonation are of the order of 27‐30 kcal · mole−1.
α‐Nitrosocyclohexanecarboxylic acid as a possible intermediate in the nitrosodecarboxylation of cyclohexanecarboxylic acid
Authors: Duynstee E. F. J. , Mevis M. E. A. H.
Published: September 2010

A description is given of the synthesis of dimeric α‐nitrosocyclohexanecarboxylic acid (III). This acid provides the first example of the hitherto unknown class of α‐nitrosocarboxylic acids. It is shown that III is not an intermediate in the nitrosodecarboxylation of cyclohexanecarboxylic acid to caprolactam.
The enzymic conversion of all‐cis 8,11,14‐eicosatrienoic acid into prostaglandin E1
Authors: Nugteren D. H. , Beerthuis R. K. , van Dorp D. A.
Published: September 2010

In the biosynthesis of prostaglandin E1 (PGE1) with an enzyme fraction of sheep vesicular glands glutathione and a moderate amount of antioxidant are required to obtain maximum yield; two oxygen molecules are consumed per mole PGE1 formed. By altering the incubation conditions, besides PGE1 various other products can be obtained.

A scheme for the mechanism of the conversion is proposed in which the formation of PGE1 as well as that of the byproducts is assumed to occur on the enzyme in concerted reactions via peroxy‐radicals and a cyclic peroxide.
The bromination of 1,4‐Di‐tert.Butylbenzene: Synthesis of 1,4‐di‐tert.butyl‐2‐bromobenzene and some tert.butyl‐dibromobenzenes
Authors: Baas J. M. A. , Wepster B. M.
Published: September 2010

The reaction of 1,4‐di‐tert.butylbenzene in carbon tetrachloride with bromine and with iron as catalyst yields 1,4‐di‐tert.butyl‐2‐bromobenzene, 1‐tert.butyl‐3‐bromobenzene, 1‐tert.butyl‐4‐bromobenzene, and 1‐tert.butyl‐3,4‐dibromobenzene. Besides these compounds, 1‐tert.butyl‐2,4‐dibromobenzene and 1‐tert.‐butyl‐2,5‐dibromobenzene were also synthesized in an unambiguous way.
The conformation of non‐aromatic ring compounds. XX: The dipole moments and NMR spectra of some 2‐substituted 1,3‐dithianes
Authors: Kalff H. T. , Havinga E.
Published: September 2010

The conformation of several 2‐substituted 1,3‐dithianes is studied by means of dipole moments and NMR spectra. The value of the dipole moments of all compounds having only hydrocarbon substituents is 2.0 ± 0.1 D., indicating that in all these compounds the six‐membered ring is in the same conformation. From the dipole moments of the 1,3‐dithianes studied it may be concluded that in solution the dithiane ring has the same geometry (chair conformation) as that found by X‐ray analysis of 2‐phenyl‐1,3‐dithiane2. The NMR spectra of 2‐methyl‐2‐phenyl‐, 2,2‐diphenyl‐ and 2‐p‐chlorophenyl‐2‐methyl‐1,3‐dithiane show that a phenyl group at atom 2 in axial position gives rise to two absorption peaks, one due to the ortho protons and one to the meta (and para) protons. The same effect is seen with the axial phenyl group in α‐trithiobenzaldehyde. The protons of an equatorial phenyl substituent give only one band. These phenomena are discussed.
The crystal structure of bis(1,3‐Diphenyl‐1,3‐Propanedionato)copper (II)
Authors: Blackstone Marijke , van Thuijl J. , Romers C.
Published: September 2010

The crystal structure of bis(1,3‐diphenyl‐1,3‐propanedionato)copper(II), Cu(C6H5CO.CH · COC6H5)2, has been determined with the aid of three‐dimensional X‐ray diffraction data. The dimensions of the monoclinic cell are a = 26.18, b = 6.07, c = 16.64 Å, β = 115.3°, Z = 4, and the space group is C2/c.

The copper ion has the square configuration with Cu‐O = 1.91 Å and with valency angles close to 90°. The chelate ring is entirely planar, the phenyl rings make small angles (9.3° and 4.6°) to this plane.

There is no indication of extensive conjugation between the phenyl groups and the chelate ring system.
Mixed carboxylic acid anhydrides: VII. Synthesis of some mixed formic acid anhydrides
Authors: Schijf R. , Stevens W.
Published: September 2010

Mixed formic acid anhydrides of high purity have been prepared by the action of acyl chlorides on sodium formate in dry tetrahydrofuran.
pH‐Measurements in alcohol‐water mixtures, using aqueous standard buffer solutions for calibration
Authors: Gelsema W. J. , de Ligny C. L. , Remijnse A. G. , Blijleven H. A.
Published: September 2010

E.m.f.‐measurements on cells of the type: Hg/Hg2Cl2/saturated KCl‐soln. (aq.)/standard buffer soln./saturated KCl‐soln.(aq.)/Hg2Cl2/Hg, using standard buffer solutions in methanol‐water and ethanol‐water mixtures and liquid‐junction forming devices of different design, showed that, for three different boundary‐types, the liquid‐junction potentials are identical within experimental error.

E.m.f.‐measurements on cells of the type: glass electrode/standard buffer soln./saturated KCl‐soln.(aq.)/Hg2Cl2‐Hg, using succinate standard buffer solutions in methanol‐water and ethanol‐water mixtures and different types of glass electrodes, proved that the variation of the standard potential of these glass electrodes with the composition of the alcohol‐water mixture does not depend on the type of glass electrode.

These results, together with the previously shown fact, that liquid‐junction potentials at the boundaries standard buffer soln. (alcohol‐water)/saturated KCl‐soln.(aq.) are independent of the nature of the buffering solute, render possible the determination of pa*H‐values of solutions in alcohol‐water mixtures by calibration of a pH‐meter with the aid of an aqueous standard buffer solution and correction of the pH‐readings with a correction term δ. For a number of methanol‐water and ethanol‐water mixtures δ‐values are tabulated and graphs, showing the variation of δ with methanol‐ and ethanol‐percentage, are given.
Dihydroquinolones IV
Authors: Speckamp W. N. , Huisman H. O.
Published: September 2010

Acylation of several N‐tosyldihydroquinolones and N‐tosylbenz[h]dihydroquinolones under alkaline conditions, gave results depending strongly on the steric volume of the ester employed. An explanation for this phenomenon is offered. The resulting α‐acylated ketones have been converted to the corresponding 2H‐pyrazolo[4,3‐c]quinolines and 2H‐benz[h]pyrazolo[4,3‐c]quinolines.
Microbiological transformation of 9β,10α‐steroids III.: 11‐Hydroxylation and side chain degradation of 9β,10α‐steroids
Authors: van der Sijde D. , de Flines J. , van der Waard W. F.
Published: September 2010

Fermentation of 17α,21‐dihydroxy‐9β,10α‐pregn‐4‐ene‐3,20‐dione with Aspergillus ochraceus yielded 11α,17α,21‐trihydroxy‐9β,10α‐pregn‐4‐ene‐3,20‐dione and 15α,17α,21‐trihydroxy 9β,10α‐pregn‐4‐ene‐3,20‐dione. Fermentation of 9β,10α‐progesterone with Aspergillus ochraceus afforded 11α‐hydroxy‐9β,10α‐progesterone.

Fermentation of the latter product with Sporomia pollaccii and Helicosporium lumbricopsis afforded 11α‐hydroxy‐9β,10α‐testosterone and 11α‐hydroxy‐9β,10α‐androst‐4‐ene‐3,17‐dione.

Fermentation of 9β,10α‐testosterone with Aspergillus ochraceus yielded 11α‐hydroxy‐9β,10α‐testosterone and 11α‐hydroxy‐9β,10α‐androst‐4‐ene‐3,17‐dione.

Fermentation of 17α‐hydroxy‐9β,10α‐progesterone with Aspergillus ochraceus afforded 11α,17α‐dihydroxy‐9β,10α‐progesterone and 11α‐hydroxy‐9β,10α‐androst‐4‐ene‐3,17‐dione.
The copper‐catalysed oxidation of unsaturated carbonyl compounds: V. Kinetics and mechanism
Authors: Volger H. C. , Brackman W.
Published: September 2010

We have investigated the kinetics of the oxidation of α,β‐ and β,γ‐unsaturated aldehydes or ketones by oxygen in methanol containing a base and a cupric pyridine complex as a catalyst. The results show that the mechanism comprises the following steps: a rate‐determining deprotonation of the substrate, yielding a dienolate anion, oxidation of this anion by the cupric complex to a dienoxy radical (or to a charge transfer complex of cupric and the dienolate anion), and oxygenation of the radical resulting in a peroxy radical, which is reduced by a cuprous complex to a γ‐hydroperoxide anion. The subsequent base‐catalysed reactions of this species were discussed in Part III of this series.

A cupric ion‐initiated chain oxidation of the substrate does not occur under the conditions applied. In the absence of oxygen the cupric complex yields a stoichiometric amount of the dienoxy radicals which combine to give α,α‐, γ,γ‐, α,γ‐ and oxygen‐γ‐dehydrodimers.

The active cupric complex contains a methoxide group and only three pyridine molecules.
Chemistry of acetylenic ethers 84: Addition of aldehydes, ketones, esters and amides to 1‐alkynyl ethers under the influence of Lewis acids; direct formation of α,β‐unsaturated esters
Authors: Vieregge H. , Schmidt H. M. , Renema J. , Bos H. J. T. , Arens J. F.
Published: September 2010

A large variety of α,β‐unsaturated esters has been prepared by addition of aldehydes and ketones to 1‐alkynyl ethers under the catalytic influence of boron trifluoride‐ether. With carboxylic esters and dimethylformamide β‐alkoxy‐ and β‐dimethylamino‐substituted acrylic esters are formed. The stereochemistry of the ester formation has been investigated.
Chemistry of acetylenic ethers 85: Preparation of compouds with a 3,5‐dien‐1‐yne system by 1,2 and 1,6 elimination of alcohols from various types of unsaturated ethers
Authors: van Boom J. H. , Brandsma L. , Arens J. F.
Published: September 2010

1,2 Elimination of HOR [R = CH3 or CH(CH3)(OC2H5)] from ethers of the types HCCCHCHCH2CH2OR and HCCCHC(CH3)CH2CH2OR, using an excess of potassium amide in liquid ammonia, affords the dienynes HCCCHCHCHCH2 and HCCCHC(CH3)CHCH2, respectively, in good yields.

1,6 Eliminations of HOR [R = CH3, C2H5, n‐C4H9, n‐C6H13, CH(CH3)(OC2H5)] from the ethers H3CCCCHCHCH2OR and H3CCC‐C(CH3)CHCH2OR have also been effected with potassium amide. The yields of the dienynes HCCCHCHCHCH2 and HCCCHC(CH3)CHCH2 obtained in this manner were good, except in the cases where R = CH3 and C2H5. 1,6 Elimination of ethanol from H5C2SCH2CCCHCHCH2OC2H5 could be achieved under milder conditions, viz. with sodium ethoxide in liquid ammonia. The dienynyl thioether H5C2SCCCHCHCHCH2 was obtained in good yield. The same compound was prepared from hexadienyne HCCCHCHCHCH2, lithium amide and diethyl disulfide C2H5SSC2H5.
Studies in transition metal chemistry. part IV: The suitability of cyclopentadienylvanadium compounds as components of Ziegler‐type polymerization catalysts
Authors: de Liefde Meijer H. J. , van der Kerk G. J. M.
Published: September 2010

The polymerization of ethylene with Ziegler‐type catalysts containing mono‐and bis‐cyclopentadienylvanadium compounds as constituents has been studied. The activities of these catalyst mixtures have been compared with those of two known highly active systems, viz. (i) the one based on biscyclopentadienyltitanium dichloride and aluminium alkyls and (ii) the one based on vanadium tetrachloride or vanadium oxytrichloride, respectively, and a large excess of aluminium alkyls. Under a wide variety of reaction conditions the cyclopentadienylvanadium compounds were found to be less active. Moreover, with vanadium, moderate activity was observed for systems based on monocyclopentadienyl derivatives and negligible to weak activity for mixtures based on biscyclopentadienyl derivatives. The large difference in suitability as catalyst constituents between the biscyclopentadienyl derivatives of titanium and of vanadium is discussed.
Some derivatives of amphetamines
Authors: Hoek W. , Wynberg Hans , Strating J.
Published: September 2010

Some derivatives of d‐methylamphetamine and dl‐amphetamine obtained by reaction of these amines with l‐glutamic acid anhydride and 1‐adamantanecarbonyl chloride are described.
Steric effect of o‐methyl groups on the ionization constants of phenols. The influence of the solvent
Authors: de Ligny C. L.
Published: September 2010

By applying McDaniel and Brown's method2 for the separation of polar and steric effects of o‐alkyl groups to Rochester's data1 for the ionization constants of methylphenols in methanol, the o‐effect of a methyl group was shown to be 0.33 ± 0.01 pK‐units.

This figure is much larger than the corresponding figure for the o‐effect in water as the solvent (0.14 ± 0.01), showing that the o‐effect is strongly solvent‐dependent and thus lending further support to the view that it is mainly caused by steric hindrance of solvation.
The synthesis of cyclopropanone: Short communication
Authors: Schaafsma S. E. , Steinberg H. , de Boer Th. J.
Published: September 2010

The synthesis of cyclopropanone from diazomethane and ketene at low temperature is described. The ketone can be kept for a few days at liquid nitrogen temperature.
Ring‐transformations in reactions of heterocyclic halogeno compounds with nucleophiles (VI): A tracer study of the conversion of 4‐chloro‐2‐phenylpyrimidine into 4‐methyl‐2‐phenyl‐s‐triazine
Authors: van Meeteren H. W. , van der Plas H. C.
Published: September 2010

By treating 4‐chloro‐2‐phenylpyrimidine‐4‐14C with potassium amide in liquid ammonia, labelled 4‐methyl‐2‐phenyl‐s‐triazine was obtained. By degradation of this s‐triazine derivative by acid hydrolysis, the 14C‐label was found to be present in one position only, viz. position 4. This result strongly indicates that in this ring‐transformation no bicyclic intermediates are involved and that the opening of the pyrimidine ring occurs by fission of the C(5)C(6) bond and not of the C(4)C(5)bond. The mechanism of this reaction is discussed.
Benzilic acid‐type rearrangement of a nitro‐olefin: Nucleophilic aromatic addition VII
Authors: de Boer Th. J. , van Velzen J. C.
Published: September 2010

14C‐labelled “trismethylene‐trinitrobenzene” (II) is oxidized by alkaline permanganate to a hydroxy‐acid (III) with a label distribution supporting a benzilic acid type rearrangement as depicted in Scheme 2.
The oxidative coupling of vinyl acetate with palladium acetate; synthesis of 1,4‐diacetoxy‐1,3‐butadiene
Authors: Kohll C. F. , van Helden R.
Published: September 2010

Vinyl acetate reacts with palladium acetate to produce 1,4‐diacetoxy‐1,3‐butadiene. In addition, 1,1,4,4‐tetraacetoxybutane and 1,1,4‐triacetoxy‐2‐butene are formed. When using palladium chloride in combination with lithium acetate no oxidative coupling takes place: vinyl acetate is then converted into acetaldehyde + acetic anhydride. The mechanism of this novel oxidative coupling reaction is discussed.
On the reactivity of organophosphorus compounds. Part III: Application of the Hammett relation to the rates of alkaline hydrolysis of a number of diethyl substituted phenyl phosphates
Authors: van Hooidonk C. , Ginjaar L.
Published: September 2010

As part of our program on the reactivity of organophosphorus compounds in nucleophilic substitution reactions the rates of alkaline hydrolysis have been determined for a number of diethyl substituted phenyl phosphates (diethyl phenyl phosphate and eight ortho‐, five meta‐ and thirteen para‐nuclear‐substituted derivatives).

The following relationships were observed:

— an excellent ϱσ correlation between the log kOH values of diethyl phenyl phosphate and four meta‐substituted derivatives and the “primary” σ values of van Bekkum et al. for meta‐substituents;

— a satisfactory correlation between the log kOH values of some ortho‐substituted compounds and Taft's σ* values for ortho‐substituents.

Calculated σ values have been compared with van Bekkum's σn values concluding very weak and no mesomeric para interactions for − M and + M substituents respectively.
The chemistry of cycloheptatriene. Part XIV: Hydrogen shifts in (4‐Dimethylaminophenyl)cycloheptatrienes
Authors: ter Borg A. P. , Kloosterziel H. , Westphal Y. L.
Published: September 2010

When the 7‐isomer of the title compound is heated, the successive formation of the 3‐, 1‐, and 2‐isomers by thermal 1–5 shifts of hydrogen is observed. Irradiation of the 3‐isomer yields the 2‐isomer. The rate constants for the various shifts are 1.7 ± 0.4 times larger than the corresponding constants for phenylcycloheptatriene.
Oxidative dimerization of β‐substituted α‐olefins by palladium acetate
Authors: Volger H. C.
Published: September 2010

α‐Olefins carrying alkyl or aryl groups as substituents at the β‐carbon atom can be oxidized by palladium acetate to 1,1,4,4‐tetra‐substituted 1,3‐butadienes. Prolonged oxidation of the primary product by an excess of the oxidant may lead to a benzene derivative.

The oxidation takes place at the terminal vinylic carbon atom exclusively.

A binuclear π‐olefin palladium acetate complex is proposed as an intermediate.