bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of spirocyclic compounds by the intramolecular michael reaction
Authors: de Jongh H. A. P. , Wynberg Hans
Published: September 2010

The double Michael reaction between the acyclic cross‐conjugated dienones dibenzalacetone or divinyl ketone and cyclohexane‐1,3‐diones gives new, substituted spiro [5,5] undecane‐l,5,9‐triones. Some of these are reduced to the corresponding spirodiketone or monoketone.
Thermodynamic study of melting equilibria under pressure of a supercritical gas
Authors: de Swaan Arons J. , Diepen G. A. M.
Published: September 2010

The modified course of the melting curve of a single substance is discussed for the case where, at its melting point, it is subjected to pressure of a supercritical gas. Unlike the melting curve of the pure substance, the new melting curve represents a three‐phase equilibrium solid‐liquid‐gas (S‐L‐G).

In section I equations are given for the slope of the S‐L‐G‐curve at the triplepoint of the least volatile component in P‐x‐, P‐T‐ and T‐x‐projections respectively. As a test the slope dP/dT is calculated for the system ethylene‐naphthalene. Agreement with the experimental value is found to within 2 %.

In section II the derivation is given of an equation for the equilibrium liquid composition as a function of pressure and temperature, provided that the solvent behaves like an ideal solution. A calculation for the system ethylenenaphthalene gives an idea of the departure from ideality at high pressures. Finally, equations are given for calculating the P‐T‐x behaviour of the S‐L‐G‐curve in the vicinity of the triplepoint of the least volatile component.
Thermal decomposition of hydrated uranium peroxides
Authors: Cordfunke E. H. P. , Aling P.
Published: September 2010

The water vapour pressure of the equilibrium between the hydrates UO4.4H2O and UO4. 2H2O has been measured as a function of the temperature. The results can be expressed as: log pH2O(mm) = 11.020 − 3082/T

Thermal decomposition of these hydrates results in the formation of amorphous (A‐) UO3, α‐UO3 or the UO2.9‐phase. These transformations were studied by thermogravimetric and differential thermal analysis.

At 520° recrystallization of these oxides takes place with formation of γ‐UO3.
Charge transfer complexes between iodine and various thioanisoles
Authors: van der Veen J. , Stevens W.
Published: September 2010

Spectrophotometric studies of solutions in cyclohexane of iodine with various thioanisoles have given results that are consistent with the formation of 1 : 1 charge transfer complexes.

The thermodynamic and spectral characteristics of these complexes have been investigated.

The equilibrium constants are in accordance with a Hammett type of relationship suggesting that complex formation depends on the electron availability of the sulphur atom in the compounds studied.
On the structure of phycaron
Authors: Hackeng W. H. L. , Copier H. , Salemink C. A.
Published: September 2010

This communication describes the isolation of new pigments from Phyllosticta caryae Peck. One of these pigments, phycaron, is identified as 1,2‐diaceto‐5,10‐dihydroxy‐3,6,9,12 (or 6,7,8,9)‐tetramethoxy‐1,2‐dihydrobenzperylene‐4,11‐quinone.
Conversion of thiolesters of α,β‐unsaturated acids into the free acids
Authors: Bos L. B. , Arens J. F.
Published: September 2010

Ethanethiolesters can be converted into free acids by:

treatment with a mixture of mercuric chloride and mercuric oxide in aqueous acetone (table I),

treatment with benzaldehyde and boron trifluoride in chloroform (table II). The latter procedure probably involves the reactions (1)‐(4).
π‐Complexes derived from the anhydride, amide, and esters of 3,5‐dinitrobenzoic acid
Authors: Buu‐Hoï N. P. , Jacquignon P. , Roussel Odette
Published: September 2010

It is shown that the anhydride, the amide, and the esters of 3,5‐dinitrobenzoic acid all give highly coloured π‐complexes with a variety of polycyclic aromatic and heterocyclic compounds. The complexes derived from the anhydride contain one molecule of the anhydride to two molecules of the electron‐donor, whilst the others are of the 1 : 1 type.
Mechanism of reactions of unsaturated ethers and thioethers. VIII: Acid‐catalyzed addition of water to 1‐alkynyl ethers
Authors: Stamhuis E. J. , Drenth W.
Published: September 2010

Additional evidence for the occurrence of a rate determining proton transfer in the hydration of 1‐alkynyl ethers is afforded by the value of the solvent deuterium isotope effect, k/k = 1.7.

The addition of water to 1‐ethoxy‐1‐propyne was investigated in a series of alcohol‐water mixtures. Application of the criterium of Grunwald indicates that a solvent molecule is not bound covalently in the slow proton transfer step.
Mechanism of reactions of unsaturated ethers and thioethers X: Neighbouring group effect in the acid‐catalyzed rearrangement of ethoxyethynyl carbinols
Authors: Hekkert G. L. , Drenth W.
Published: September 2010

The velocity of the acid‐catalyzed hydration of 1‐alkynyl ethers, RCCOC2H5, has been determined, and the second order rate constants are correlated with Taft's equations. This correlation is used to estimate the rate of rearrangement of ethoxyethynyl carbinols, R2C(OH)CCOC2H5, into α,β‐unsaturated esters. The experimental values are approximately one power of ten larger, suggesting an anchimeric effect of the hydroxyl group.
Mechanism of reactions of unsaturated ethers and thioethers. XI: Acid‐catalyzed addition of water to 1‐alkynyl thioethers
Authors: Hogeveen H. , Drenth W.
Published: September 2010

Infrared analysis has shown that acid‐catalyzed hydration of ethylthioethyne in heavy water does not involve the uptake of deuterium in the initial compound. This confirms earlier evidence that protonation of the triple bond is the rate‐determining step.

Values for the entropy of activation of five 1‐alkynyl thioethers were determined. They range between −1 and −6 e.u. The rate of hydration of 1‐tert.‐butylthio‐1‐propyne in 0–98.7 weight‐percent ethanol‐water mixtures has been analyzed by a theory of Grunwald. A plot of (log k1−log fH⊕) against Y0 gives a straight line. The triple bond of vinylthioethyne has been hydrated in moderately concentrated perchloric acid solutions. A Zucker‐Hammett plot of these data affords a straight line with a slope of 1.07 and a Bunnett plot a “straight” line with a slope of −0.9. These facts suggest that the addition of the water molecule takes place in a step subsequent to protonation.
Miscellaneous glycerol derivatives: I. Diacylglycerol‐iodohydrins
Authors: Verkade P. E.
Published: September 2010

Some new diacylglycerol‐iodohydrins are described.
The chemistry of sulfenyl halides: Part III: Photochlorination of alkyl chlorides with trichloromethylsulfenyl chloride
Authors: Kloosterziel H.
Published: September 2010

The photochlorination of some alkyl chlorides with trichloromethylsulfenyl chloride has been investigated. Product distributions and reactivities relative to alkanes were determined. The results show the importance of polar effects and can be correlated with the polar substituent constants σ*. A chlorine atom reduces the reactivity of a neighbouring carbon‐hydrogen bond by a factor of 45. The reactivities at other positions correspond to a loss factor of 1.6. A methyl group exerts a slight activating polar effect.

A correlation with NMR chemical shifts suggests that the differences in reactivity of methylene groups in hydrocarbons, as reported in Part II 2, are also due to polar effects.
The thermal decarboxylation of sodium trichloroacrylate in an aprotic medium
Authors: Wagner W. M. , Vriesman L. , Kloosterziel H. , Bickel A. F.
Published: September 2010

Sodium trichloroacrylate decomposes in 1,2‐dimethoxyethane at 90° to give quantitative yields of CO2 and NaCl. Evidence is presented that this decarboxylation involves the trichlorovinyl anion, CCl2CCl−, as an intermediate.
On the impedance of galvanic cells: VIII. The abnormal behaviour of the Tl+/Tl(Hg) electrode
Authors: Sluyters‐Rehbach M. , Timmer B. , Sluyters J. H.
Published: September 2010

The anomalous behaviour of the Tl+/Tl(Hg) electrode in 1 KNO3 + 0.1 M KCl solution has been studied experimentally applying the theory described in parts IV and VI of this series. It is shown that this anomaly can be explained assuming that the double layer capacity increases on adding thallous ions. The increase Δ C appears to be proportional to the TI+ concentration. The phase angle Φ of the faradaic impedance is equal to π/4.
A new synthesis of nitriles
Authors: Brackman W. , Smit P. J.
Published: September 2010

Nitriles can be obtained in good yields (60‐80%) by treatment with oxygen at 30° of a methanolic solution of the corresponding aldehyde, containing ammonia, a strong base and a catalytically active copper complex. Yields are lower for base‐sensitive aldehydes.

In a similar way, but in much poorer yields, cyanide and cyanate are formed from methanol, ammonia and oxygen, and isonitriles from methanol, a primary aliphatic amine and oxygen.
Synthesis and anthelmintic activity of isopelletierine and a series of side‐chain homologues
Authors: van Noordwijk J. , Mellink J. J. , Visser B. J. , Wisse J. H.
Published: September 2010

The preparation and anthelmintic properties of isopelletierine and four side‐chain homologues are described. The compounds were prepared from Δ1‐piperideine and 3‐oxo‐acids at pH 4‐5. pK′a− and Rf‐values were determined. Anthelmintic activity as tested in vitro on the liver fluke, by three methods, was highest for 1‐(2′‐piperidyl)butanone‐2. The differences in anthelmintic properties of the compounds are discussed.
Mechanism of reactions of unsaturated ethers and thioethers XII: Reaction of 1‐ethoxyvinyl esters with carboxylic acids in non‐aqueous solvents
Authors: Zwanenburg B. , Drenth W.
Published: September 2010

The reaction of 1‐ethoxyvinyl esters and carboxylic acids has been investigated in non‐aqueous solvents. The kinetics in benzene follow the rate expression

V = k30 · C1‐ethoxyvinyl ester · C2acid

while in dioxan and sulpholane the following equation is obeyed

V = (k30 · C2acid + k4 · C3acid) · C1‐ethoxyvinyl ester

The rate constants in sulpholane are 20 to 30 times as large as those in dioxan, while the rate of reaction in benzene is approximately equal to that in sulpholane. The kinetic isotope effect, kH/kD, for the reaction of 1‐ethoxyvinyl acetate and either acetic acid or O‐deuteroacetic acid, amounts to 4.0 in benzene and to 3.6 in sulpholane as solvent. During this reaction no deuterium was incorporated into the vinyl ester molecule.

Addition of tetrabutylammonium perchlorate to the solvent dioxan increases the rate constant of the reaction between 1‐ethoxyvinyl chloroacetate and chloroacetic acid in accordance with the equation

k3 = (k3)conc. salt = O (1 + b · Csalt)

The value of the coefficient b amounts to 4 1/mole.

From these results it was concluded, that in a number of pre‐equilibria a solvation complex is formed between a molecule of 1‐ethoxyvinyl ester and two, three or four molecules of carboxylic acid. These pre‐equilibria are followed by the rate determining step in which a proton is transferred to the substrate giving an ion pair as intermediate. The products are formed from this ion pair.
Thermal substitution reactions of cupric benzoate IV
Authors: Schoo W. , Veenland J. U. , van Velzen J. C. , de Boer Th. J. , Sixma F. L. J.
Published: September 2010

The reaction of cupric benzoate with carbon tetrachloride leads to the formation of a mixture of benzoyl chloride and ortho‐chlorobenzoyl chloride. On the basis of these data, the reactions of cupric benzoate are reconsidered. Most probably at about 200° the cupric benzoate forms a radical, stabilised by interaction of the cupric‐ion with the ortho position. With this stabilised radical all the reactions described in this and previous1,2,3 papers can be explained.
Efficiency of chromatographic procedures: II. Optimum conditions for the separation of the antipodes of DL‐kynurenin by paper adsorption chromatography
Authors: de Ligny C. L. , Schmidt H. M. , de Vries W.
Published: September 2010

The influence of the kind of paper and the temperature on the separation of the antipodes of DL‐kynurenin has been investigated.
Thermodynamic properties of transition metal compounds and coordination complexes III. Heats of formation of some complexes of the divalent metals Mn ‐ Zn
Authors: Schuit G. C. A.
Published: September 2010

The heats of formation of octahedrally coordinated complexes of O‐containing ligands follow a relationship, proposed earlier

while those of N‐containing ligands follow a more involved equation

where I‐the ionization potential (I1 + I2 of the atom, CL, ΔL and γL are constants dependent on the ligand, while nt and ne are the number of 3d‐electrons in the t2g and the eg‐antibonding orbitals. For O‐ligands, as for those ligands discussed previously ΔL ∼ Δs (spectroscopic ligand field splitting factor), while for N‐ligands, (ΔL + γL) ∼ Δs. It is proposed that γL represents the depression in energy of the t2g‐levels by acceptor π‐bonding connected with a 3p‐orbital of atomic N: it is numerically equal to 6 kcal/at for a central ion with an environment of 6 N‐atoms.

The ΔL and CL‐values for O‐ and N‐containing ligands appear almost equal, suggesting the σ‐bonds to be almost equal in strength.
Synthesis of a completely protected pentapeptide found in bacterial cell walls
Authors: Tesser G. I. , Nivard R. J. F.
Published: September 2010

A synthesis is described of a protected pentapeptide, in which the amino‐acid sequence L‐alanyl‐D‐glutamyl‐L‐lysyl‐D‐alanyl‐D‐alanine, found in bacterial cell wall substances, is present. By the nature of its amino‐ and carboxyl‐protecting groups it seems suitable for condensation with N‐acetylmuramic acid, which is intended.
Synthesis of mixed‐acid phosphatidylserine containing unsaturated fatty acids
Authors: de Haas G. H. , van Zutphen H. , Bonsen P. P. M. , van Deenen L. L. M.
Published: September 2010

The synthesis is described of a mixed‐acid phosphatidylserine, containing one saturated and one unsaturated fatty acid, by a reaction between γ,β‐diacylglycerol‐L‐α‐iodohydrin and silver N‐t. butoxycarbonyl‐O‐(O‐benzylphospho)‐DL‐serine t. butyl ester.

Some physical and biochemical properties of the unsaturated phosphatidylserine, viz. (γ‐oleoyl‐β‐palmitoyl)‐L‐α‐phosphatidyl‐DL‐serine, are given.
Reaction of aliphatic orthoformates with tetrachlorogermane
Authors: Pike R. M. , Dewidar A. M.
Published: September 2010

The synthesis of tetraalkoxy‐ and chloroalkoxygermanes is described. The method employed consists of the treatment of tetrachlorogermane with trialkyl orthoformates.
Chemistry of acetylenic ethers 70: Preparation of 1‐alkynyl thioethers and 1‐alkynyl selenoethers from sodium alkynylides, sulphur or selenium and alkyl halides
Authors: Brandsma L. , Wijers H. E. , Jonker C.
Published: September 2010

A number of 1‐alkynyl thioethers and selenoethers RCC‐XR′ (XS or Se) have been prepared by reaction of sodium alkynylides, dissolved in liquid ammonia, with sulphur or selenium, followed by alkylation. 1,3‐Enynyl thioethers, RCHCH‐C≡C‐SR′, ω,ω‐diynyl thioethers R′S‐C≡C‐(CH2)n‐C≡C‐SR′ and 1,3‐diynyl thioethers RC≡C‐C≡C‐SR′ also can be obtained in this manner. The yields are satisfactory, except in the case of the ethynyl thioethers HC≡C‐SR′. Alkylselenoacetylenes HC≡C‐Se R′ are not accessible by this method.
On the impedance of galvanic cells: IX. The double layer capacity of the mercury‐1 M HCIO4 solution interface at high d.c. potentials
Authors: Sluyters‐Rehbach M. , Sluyters J. H.
Published: September 2010

The values of the double layer capacity of the mercury‐1 M HCIO4 solution interface at potentials where the dissolution of Hg contributes to the cell impedance, have been determined by the method previously described in parts VI1 and VII2.
Paper chromatography of diastereoisomeric tetrapeptide derivatives: Short communication
Authors: Kienhuis H. , Verweij A.
Published: September 2010

In six solvents the L‐D diastereoisomers of H‐gly‐asp‐ser‐gly‐OEt, H‐gly‐glu‐ser‐gly‐OEt, H‐gly‐asp‐ser(Ac)‐gly‐NH2 and H‐gly‐glu‐ser(Ac)‐gly‐NH2 have higher Rt values than the corresponding L‐L diastereoisomers.
Chemical determination of the cation valencies in cubic MntFe3‐tO4
Authors: Driessens F. C. M.
Published: September 2010

An analytical method is given for determining the distribution of cation valencies in MntFe3‐tO4 for o < t < 1.5 at 240°, based on the assumption that the existence of only Fe2+, Fe3+, Mn2+ and Mn3+ is possible and that no change in the equilibrium of the valencies occurs during rapid dissolution. The results are given for t = 0.50, 0.75, 1.00, 1.25 and 1.50. It is shown that near t = 1 the cations Mn3+ and Fe2+ are present simultaneously: The formula of manganese ferrite is found to be

with a possible error of ± 0.025 in the cationic ratio numbers.

In addition the temperature dependence of the valence distribution is discussed.
A comparison of polarographic reduction potentials of some substituted benzoquinolizinium compounds
Authors: Frost Jackie G. , Saylor John H.
Published: September 2010

The presence of substituted side groups on the benzoquinolizinium ion has a measurable effect on the magnitudes of the reduction potentials. Qualitative relationships between inductive and/or resonance effects of these side groups and the corresponding half‐wave potentials are discussed.
A convenient synthesis of 9,10‐dihydrophenanthrene‐9‐carboxylic acid
Authors: de Koning H. , Wiedhaup K. , Pandit U. K. , Huisman H. O.
Published: September 2010

Reduction of 9‐phenanthroic acid with sodium and liquid ammonia results in the formation of 9,10‐dihydrophenanthrene‐9‐carboxylic acid in high yield.
Separation of homologous cerebrosides by silica gel column and thin‐layer chromatography
Authors: Hooghwinkel G. J. M. , Borri P. , Riemersma J. C.
Published: September 2010

Cerebroside mixtures isolated from beef spinal cord lipids can be chromato‐graphically resolved into twelve or more components. The technique employed was multiple thin‐layer chromatography with a newly developed solvent. A fractionation of the cerebrosides could also be obtained by silicic acid column chromatography using chloroform‐methanol mixtures. The fractions were characterized (a) by thin‐layer chromatography; (b) by gas chromatography of the fatty acid methyl esters obtained after methanolysis of the cerebrosides. It could be shown that the chromatographic behaviour of cerebrosides is decisively influenced by the nature of their fatty acid component.
On the impedance of galvanic cells: X. The impedance of the H⊕/H2(Hg) electrode in 1 M perchloric acid
Authors: Sluyters‐Rehbach M. , Sluyters J. H.
Published: September 2010

From impedance measurements it is shown that the hydrogen ion reduction on mercury behaves as a case of pure activation polarization between ‐1.1 and ‐1.3 V vs S.C.E. with 1‐α = 0.56 and ksh = 10−15 cm · sec−1. The value of the double layer capacity in that potential range is reported. No influence of hydrogen on the double layer capacity could be observed.
Synthesis of some analogs of cryptopleurine
Authors: Bradsher C. K. , Desai R. B.
Published: September 2010

The alkaloid cryptopleurine (Va) is a phenanthroquinolizidine derivative which is physiologically active2–4 but quite toxic 5, even showing marked vesicant activity 5, 6. As part of a program involving the synthesis of benzo‐quinolizidine analogs 7–9 as for testing as possible hypotensive agents (blood‐pressure lowering agents), we have prepared several simplified analogs of cryptopleurine. While the method used is a variant of that originally applied in the cryptopleurine synthesis10, the use of the more modern techniques involving the substitution of 2‐(1,3‐dioxolan‐2‐yl)pyridine11 or picolinaldoxime12 (II. Z = NOH) for picolinaldehyde (II. Z = O) has made possible in most cases the isolation of the intermediates III and IV. The phenanthro‐quinolizidines prepared (as salts) include the 2,3‐dimethoxy‐(Vb), the 6‐methoxy‐(Vc) and the unsubstituted (Vd).
Studies on polypeptides I: Synthesis and activity of angiotensin analogues (mostly heptapeptides) in which the arginine moiety is replaced by similar residues of varied structure and configuration
Authors: Havinga E. , Schattenkerk Cecile , Visser G. Heymens , Kerling K. E. T.
Published: September 2010

Peptides with the “angiotensin” sequence X‐Val‐Tyr‐Ile‐His‐Pro‐Phe1 have been synthesized in which X represents H, L‐Arg, D‐Arg, L‐Har, D‐Har, L‐Lys, D‐Lys, L‐Hly, D‐Hly, L‐Orn, L‐Cit, L‐Asp(NH2) ‐L‐Arg, L‐Asp(NH2) ‐D‐Arg and Gly‐L‐Arg1. The relation between structure and configuration versus pressor activity of these peptides is briefly discussed. One of the regularities found is that the heptapeptides having a D‐(N‐terminal) residue show significantly higher activities than the corresponding L‐amino‐acid derivatives.
Studies on polypeptides III: Synthesis of the heptapeptides (des‐Asp1)‐Arg2‐Ile5‐Angiotensin II, (des‐Asp1)‐D Arg2‐Ile5‐Angiotensin II, (des‐Asp1)‐ Har2‐Ile5‐Angiotensin II, (des‐Asp1)‐D Har2‐Ile5‐Angiotensin II and the octapeptides Asp1 (NH2)‐Ile5‐Angiotensin II, Asp1 (NH2)‐D Arg2‐Ile5‐Angiotensin II and Gly1‐Ile5‐Angiotensin II
Authors: Visser G. Heymens , Schattenkerk Cecile , Kerling K. E. T. , Havinga E.
Published: September 2010

In a previous communication

Paper no. II: C. Schattenkerk, G. Heymens Visser, K. E. T. Kerling and E. Havinga, Rec. Trav. Chim. 83, 677 (1964)

the syntheses of four heptapeptides related to angiotensin II were reported, in which the L‐arginine moiety was replaced by L‐and D‐lysine, L‐ornithine and L‐citrulline. We now report experimental details of the synthesis of four other heptapeptides and three octapeptides. The activity of these compounds in the pressor tests have been discussed in publication no. I of this series. The arginine and homoarginine heptapeptides were synthesized by coupling the mixed anhydride of the appropriate Z‐nitro compound with the hexapeptide benzyl ester H‐Val‐Tyr‐Ile‐His‐Pro‐Phe‐OCH2C6H5

Paper no. II: C. Schattenkerk, G. Heymens Visser, K. E. T. Kerling and E. Havinga, Rec. Trav. Chim. 83, 677 (1964)

. The L‐ and D‐nitrohomoarginine used were prepared by nitroguanidation of L‐and D‐lysine with nitromethylisourea

N. Heyboer, G. Heymens Visser and K. E. T. Kerling, ibid. 81, 69 (1962.

For the synthesis of the octapeptides, the first of which had been prepared earlier by Schwyzer et al. using a different method

W. Rittel, B. Iselin, H. Kappeler, B. Riniker and R. Schwyzer, Helv. Chim. Acta 40, 614 (1957).

, Z‐Arg(NO2)‐Val‐Tyr‐Ile‐His‐Pro‐Phe‐OCH2C6H5 was decarbobenzoxylated by hydrobromic acid in acetic acid and the resulting heptapeptide benzyl ester coupled with Z‐Asp(NH2)‐ONP and Z‐Gly‐ONP.
A new synthesis of 9‐oxodec‐2‐enoic acid
Authors: van der Plas H. C. , Persoons C. J.
Published: September 2010

A new synthesis of 9‐oxodec‐2‐enoic acid, using thiophen as one of the starting materials, is described.
Reduction of 6‐nitroquinoline with phosphine
Authors: Bellaart A. C.
Published: September 2010

Reduction of 6‐nitroquinoline with phosphine under the conditions described by Buckler yields 6,6′‐azo‐5,5′‐diquinolyl along with 6,6′‐azoxyquinoline.
Investigations on organogermanium compounds. II: Further studies on redistribution reactions
Authors: Rijkens F. , van der Kerk G. J. M.
Published: September 2010

Further investigations have shown redistribution reactions to be generally applicable to the preparation of substituted chlorogermanes, with the exception of the methylchlorogermanes.

The relative reactivity of the compounds (C6H5)nGeCl4‐n (n = 0, 1 or 2) with respect to phenylation by tetraphenylgermane in the presence of aluminium trichloride was found to be (C6H5)2GeCl2 > C6H5GeCl3 > GeCl4.

Using a modified procedure it proved possible to carry out most of the reactions at atmospheric pressure. The limitations of this procedure are pointed out.

The reactions require a catalyst. As such, aluminium compounds of the general formula RnAlCl3‐n (n = 0, 1, 2 or 3) are most suitable.
The ternary system: Carbon tetrachloride ‐ water ‐ tributyl phosphate (TBP)
Authors: van Aartsen J. J. , Korvezee A. E.
Published: September 2010

This work forms part of a study of the extraction equilibria in the quaternary system uranyl nitrate‐water‐TBP‐carbon tetrachloride.

In the ternary system CCl4‐H2O‐TBP two liquid layers occur. From the three binaries that limit this system the pairs TBP‐H2O and CCl4‐H2O have a miscibility‐gap, while the pair TBP ‐CCl4 is fully miscible.

The extremely asymmetric miscibility‐gap in the system water‐tributyl phosphate (TBP) has given rise to the assumption that a compound with composition H2O · TBP is formed. A number of authors have argued for the existence of this compound, based on spectral evidence. We have measured the freezing point diagram and some solubility data in this system as a function of temperature. From the results we conclude that the compound mentioned does not exist to any appreciable concentration in solutions of water in TBP, although these solutions show an appreciable deviation from ideality. This non‐ideal behaviour was investigated by isopiestic vapour pressure measurements. Data on the activity coefficients of water in TBP are given at 25.0°. They are represented by the equation

In f = x2 [1.563 ‐ 1.143 (4 x ‐ 3) + 0.682 (2 x ‐ 1) (6 x ‐ 5)] x being the mole fraction of TBP.

Data on vapour pressures and activity coefficients for the binary TBP ‐CCl4 are given at 25.0°. In the ternary phase diagram the miscibility boundary has been determined at the same temperature.
Zirconium silicide and germanide chalcogenides preparation and crystal structures
Authors: Klein Haneveld A. J. , Jellinek F.
Published: September 2010

The tetragonal sublimates obtained by prolonged tempering of preparations of compositions about ZrX0.75 (X = S, Se, Te) in evacuated quartz tubes1, 2, are found to be ternary compounds ZrSiX. These novel compounds can be prepared conveniently by reaction of “SiX” with zirconium metal at elevated temperatures. The analogous germanium compounds are prepared in a similar way. The crystal structures of the ZrSiX and ZrGeX phases are related to the PbFCl structure type. Unit‐cell dimensions, atomic parameters (see Table I) and interatomic distances (see Table II) have been determined; they are discussed in some detail.
The influence of steric and electronic factors on acidity. I. β‐arylthio‐, β‐arylsulfinyl‐ and β‐arylsulfonyl‐acrylic acids. Transmission of substituent effects by S, SO and SO2, and effect of cis‐ trans geometry
Authors: Hogeveen H.
Published: September 2010

The apparent acidity constants of substituted β‐phenylthio‐, β‐phenylsulfinyl‐and β‐phenylsulfonyl‐acrylic acids (cis and trans) with substituents p‐OCH3, p‐CH3, H, p‐Cl, m‐NO2 and p‐NO2 have been determined in 50% (by vol.) aqueous ethanol. The acidity constants in the six series obey the Hammett equation with satisfactory to excellent fit. The values of the reaction constants δ indicate that substituent effects are better transmitted by S than by SO and SO2, and they do not differ substantially for cis and trans series.

The β‐arylthioacrylic acids are more acidic in trans‐ than in cis‐configuration, while the opposite holds for the β‐arylsulfinyl‐ and β‐arylsulfonyl‐acrylic acids. These differences are discussed in terms of steric inhibition of resonance and electrostatic effects through space.

Comparison between the acidity constants of trans‐β‐substituted acrylic acids with those of para‐substituted benzoic acids reveals that a carbon‐carbon double bond is 1.9 times as effective as the phenyl ring in the transmission of electronic effects.
On the Hg2++/Hg electrode reaction: Comparison of complex plane analysis, double pulse galvanostatic step and faradaic rectification method
Authors: Sluyters‐Rehbach M. , Sluyters J. H.
Published: September 2010

A comparison is made of studies of the Hg2++/Hg electrode by means of complex plane analysis 1, 2 and double pulse galvanostatic step 4. As a possible explanation for the inconsistent results, interference by the double layer capacity in the latter method is suggested. It is shown that the results obtained for the same electrode by Imai and Delahay3 with faradaic rectification do not satisfy the conditions required for the approximations introduced. The exchange current densities are likely to be larger than reported. Another approximation procedure is proposed, which applies for very fast electrode processes (k0a > 3.10−3√ω.
Mollisin, a naturally occurring chlorine‐containing quinone: Part III,. The synthesis of dechloromollisin methyl ether and of related compounds
Authors: Overeem J. C. , van der Kerk G. J. M.
Published: September 2010

A survey is given of the synthetic experiments which have led finally to the synthesis of 8‐acetyl‐5‐methoxy‐2,7‐dimethylnaphthoquinone‐1,4. The synthetic compound proved to be identical with dechloromollisin methyl ether.

Additional evidence is presented for the structure of the compound, leuco‐anhydrodechloromollisin.
Mollisin, a naturally occurring chlorine‐containing quinone: Part IV,. Revised structures for cochenillic acid and for the insect pigments, carminic and kermesic acids
Authors: Overeem J. C. , van der Kerk G. J. M.
Published: September 2010

4‐Methoxy‐6‐methylhemimellitic acid and its isomers, 3‐methoxy‐5‐methyltrimellitic and 5‐methoxy‐3‐methyltrimellitic acid have been synthesized. 4‐Methoxy‐6‐methylhemimellitic acid is identical with a degradation product of mollisin methyl ether. Evidence is presented from which it must be concluded that cochenillic acid ‐ a degradation product of the well‐known insect pigments carminic and kermesic acids ‐ considered since 1897 to be 4‐hydroxy‐6‐methylhemimellitic acid is in fact 5‐hydroxy‐3‐methyltrimellitic acid. From this it follows that the current structural formulae of carminic and kermesic acids must be revised.
Preparation of 5‐chloro‐3,6‐dimethyl‐2‐benzofurylacetic acid
Authors: Deorha D. S. , Gupta Padma
Published: September 2010

The reaction of 4‐[(5′‐chloro‐3′,6′‐dimethyl‐2′‐benzofuranyl)methylene]‐2‐phenyloxazolin‐5‐one with hydrazine hydrate gives α‐benzamido‐β‐(5‐chloro‐3,6‐dimethyl‐2‐benzofuryl)acrylohydrazide which is converted to the corresponding azide by nitrous acid. On heating in benzene, the azide yields 4‐[(5′‐chloro‐3′,6′‐dimethyl‐2′‐benzofuranyl)methyl]‐2H‐6‐phenyl‐1,3,5‐oxadiazin‐2‐one the hydrolysis of which furnishes 5‐chloro‐3,6‐dimethyl‐2‐benzofurylacetic acid.
The absolute configuration of mimosine
Authors: Beyerman H. C. , Maat L. , Hegarty M. P.
Published: September 2010

Degradation of the plant amino acid (‐)‐mimosine yielded optically pure (+)‐α,β‐diaminopropionic acid hydrobromide identical with the acid obtained from L‐asparagine. (‐)‐Mimosine therefore belongs to the Ls‐series.
Peptide derivatives related to the active site of some hydrolytic enzymes III. Syntheses and some physical properties of tetrapeptide derivatives protected by N‐acetyl and amide groups
Authors: Kienhuis H. , van der Holst J. P. J. , Verweij A.
Published: September 2010

For our investigations of model compounds related to the active site of esterases some new peptide derivatives containing the amino acid sequences gly‐asp‐ser‐gly, gly‐glu‐ser‐gly and gly‐gly‐ser‐gly were synthesized. The compounds were obtained by coupling two dipeptide derivatives using the mixed anhydride procedure. The azide method was used to prepare the dipeptide derivatives. The products thus obtained possessed the L‐L configuration. Some physical data, including the dissociation constants, were determined.
Orientation dans la Réaction de Friedel‐Crafts D'acétylation des Bromofluorobenzènes
Authors: Quang N. N. , Diêp Bui K. , Buu‐Hoï N. P.
Published: September 2010

Il est montré que dans la réaction de Friedel‐Crafts d'acétylation de l'o‐ et du m‐bromofluorobenzène, le groupement acétyle occupe la position para par rapport au fluor; dans la même réaction avec le p‐bromofluorobenzène, le groupement acétyle occupe la position ortho par rapport au brome. Ces résultats sont parallèles à ceux obtenus auparavant sur les chlorofluorobenzènes.
The system NbCl5 ‐ Nb2O5: II. The P ‐ T projection
Authors: Hart W. 't , Meyer G.
Published: September 2010

The measurement of the vapour pressure as a function of the temperature of a number of equilibria in the above‐mentioned system is described. The vapour pressures found may be expressed as follows:

The three‐phase equilibrium S − S ‐ G: log Patm = ‐ 73.4680 + 27.0705· log T ‐ 0.0030359 T (610‐701.5°K.

The three‐phase equilibrium S ‐ L ‐ G: log Patm = 7.4229 ‐ 4193.4/T (701.5‐716°K.

The three‐phase equilibrium S ‐ L ‐ G: log Patm = 313.0179 ‐ 15664.84/T ‐ 112.9694· log T + 0.0460236 T (530‐695°K.

The two‐phase equilibrium NbCl5(L ‐ G): log Patm = 56.5395 ‐ 5494.8/T ‐ 17.7882· log T + 0.0044913 T (540‐715°K.

For the situation of the quadruple point S ‐ S ‐ L ‐ G we found 701.5°K and 27.90 atm.
Mixed carboxylic acid anhydrides: III. Esterification of phenols with the formic acid/acetic anhydride reaction mixture
Authors: Stevens W. , van Es A.
Published: September 2010

The reaction of the formic acid/acetic anhydride reaction mixture with phenols at room temperature affords mainly the formates together with acetates. The quantity of acetates formed can be reduced by carrying out the esterification in solutions of benzene, carbon tetrachloride and other solvents. This finding has led to the synthesis of pure aryl formates.
The influence of non planarity in styrene and stilbene derivatives V: Infrared spectra and conformations of cis‐ and trans‐benzal ketones
Authors: Kronenberg M. E. , Havinga E.
Published: September 2010

The infrared spectra of a number of cis‐ and trans‐benzal ketones have been recorded. The carbonyl stretching frequencies can be understood by taking into account the occurrence of rotational isomerism. The spectra of cis‐benzal acetones suggest that these compounds occur predominantly in one conformation.
Metastable transitions in the mass spectra of five saturated fatty acid methyl esters
Authors: Sonneveld W.
Published: September 2010

A number of metastable peaks in the mass spectra of methyl acetate, propionate, butyrate, valerate and hexanoate were investigated. By measuring the kinetic energy of the ions of those peaks 28 degradation reactions of the esters were determined.
Titration of ferrocyanide with silver nitrate, using potassium chromate as indicator
Authors: Rao K. Bhaskara
Published: September 2010

The use of potassium chromate as indicator in silver‐ferrocyanide titration has been studied. It has been found that silver‐ferrocyanide titration can be conducted satisfactorily in neutral or nearly neutral medium, using potassium chromate as indicator.
The free enthalpies of transfer from water to water‐methanol mixtures for single ions
Authors: De Ligny C. L. , Alfenaar M.
Published: September 2010

A method is devised for the determination of free enthalpies of transfer from one solvent to another for single ions. Results are given for the transfer from water to water‐methanol mixtures.
The chromatographic behaviour of calcium‐aluminium‐alizarate on alumina
Authors: Kiel E. G. , Heertjes P. M.
Published: September 2010

The behaviour of the calcium‐aluminium‐alizarate complex on alumina is described. By elution with mixtures of dimethylformamide and water two fractions can be isolated. It has been shown that these fractions are not cis‐trans isomers. In all probability the two fractions differ in the charge distribution of the electrons, caused by a difference in water content.
Proton magnetic resonance spectra of the dihydrofurans and dihydrothiophenes
Authors: Korver P. K. , van Der Haak P. J. , Steinberg H. , De Boer T. H. J.
Published: September 2010

The proton chemical shifts and coupling constants in the isomeric dihydrofurans and dihydrothiophenes have been determined using the proton‐proton decoupling technique, where necessary. The coupling constants in both 2,5‐dihydro‐compounds were found to be less than 0.5 c/s. In the 2,3‐dihydro‐compounds the influence of the heteroatom on the coupling constant between the olefinic protons is large as compared with that on the other coupling constants. The differences between the chemical shifts of the protons in the 2,3‐dihydrofurans and those of the corresponding protons in the 2,3‐dihydrothiophenes can be explained by the larger electronegativity of the oxygen atom and the larger diamagnetic anisotropy of the double bond in the thiophene derivative.
Chemistry of α‐diazosulfones: Part IV. The preparation of N‐(arylsulfonylmethyl)urethanes and N‐(alkylsulfonylmethyl)urethanes
Authors: van Leusen A. M. , Strating J.
Published: September 2010

In the synthesis of α‐diazosulfones (subsequent paper2) the N‐(sulfonylmethyl)urethanes, RSO2CH2NHCO2C2H5, are important intermediates. They have been prepared by means of a Curtius rearrangement of sulfonylacetazides, RSO2CH2CON3, which in turn have been obtained from the corresponding esters via the hydrazides.
Mechanism of reactions of α‐diazosulfones. II: The acid‐catalysed hydrolysis in water and in dioxan‐water mixtures
Authors: Zwanenburg B. , Engberts J. B. F. N.
Published: September 2010

The acid‐catalysed hydrolysis of α‐diazosulfones has been studied in water and in dioxan‐water solutions. From the magnitude of the solvent deuterium isotope effect a fast reversible protonation of the substrate is proposed. This result is supported by H‐D exchange experiments. The reaction rates have been measured in moderately concentrated perchloric acid and hydrochloric acid solutions. The logarithm of the pseudo first order rate constant is linear in Hammett's acidity function, H0. The slopes of these linear plots are appreciably larger for hydrochloric acid than for perchloric acid as catalyst. Bunnett's theory has been used to interpret the rate data in water. The influence of added sodium perchlorate and sodium chloride on the reaction rate is compared. A bimolecular rate‐determining step is proposed with a weak participation of the nucleophile in the transition state. The entropies of activation are consistent with this conclusion. The failure of the Zucker‐Hammett hypothesis is discussed.

The influence of para substituents in five aryl α‐diazosulfones is correlated with Hammett's σp and Tsuno's σ+ constants. A weak transition state resonance has been proposed for p‐methoxyphenylsulfonyldiazomethane.

Preliminary measurements on the hydrolysis of alkyl α‐diazosulfones are pointing to a similar mechanism to that proposed for the aryl α‐diazosulfones.
Electron diffraction by gases the molecular structure of monochlorodimethyl ether
Authors: Planje M. C. , Toneman L. H. , Dallinga G.
Published: September 2010

The structure of monochlorodimethyl ether has been reinvestigated by means of electron diffraction of the vapour. The rotation of both the chloromethyl group and the methyl group is restricted; the chlorine atom is approximately in the gauche position with respect to the O‐C bond. The carbon‐chlorine bond length is 1.813 Å, significantly larger than in chloroalkanes. The bond between the chloromethyl carbon atom and the oxygen atom is shorter than the carbonoxygen bond in aliphatic ethers.
The isocoumarin analogue of dicoumarol
Authors: Buu‐Hoi N. P. , Jacquignon P. , Mangane M.
Published: September 2010

Isochroman‐1,4‐dione reacted with formaldehyde to give a methylenebis compound which is the exact analogue of dicoumarol, although it lacks the latter's potent anticoagulant properties. A similar reaction was observed with pyridine‐2‐aldehyde, but with benzaldehyde, 3‐benzylideneisochroman‐1,4‐dione was obtained.
The structure of the tetrachlorobisdimethylamino‐and trichlorotrisdimethylamino‐1,3,5,2,4,6‐triazatriphosphorine
Authors: Koopman H. , Spruit F. I. , van Deursen F. , Bakker J.
Published: September 2010

The purpose of the investigation was to gather data on the course of the substitution of chlorine by dimethylamine in hexachloro‐1,3,5,2,4,6‐triazatriphosphorine. In the course of this reaction a geminal substitution occurs besides the consecutive substitution in the 2,4 and 6 positions. The structure of the three tetrachlorobisdimethylamino and the three trichlorotrisdimethylamino‐1,3,5,2,4,6‐triazatriphosphorine was determined. Contrary to previously published results1, the 2,4‐bisdimethylamino derivative already described by Becke Goehring2 has the trans configuration.
Heats of combustion of normal saturated fatty acids and their methyl esters
Authors: Adriaanse N. , Dekker H. , Coops J.
Published: September 2010

Accurate heats of combustion of the title compounds were measured in an electrically calibrated calorimeter; the liquid samples were burned in Pyrex ampoules; the water content in the samples was titrated by the Karl Fischer method.

The increment of the standard enthalpy of combustion, ‐ΔHR25liq. (=‐ΔHC0liq.) for one CH2 group in the chain proved to be 653.8 kj/mole for both the acids and the methyl esters studied, which is the same value as determined for the liquid paraffins. The following formulae, in which c = the number of carbon chain atoms (c > 5) can be used to calculate the standard enthalpies of combustion (based on the 1951 atomic weights):

‐ΔHliq. = 653.8 c − 430.2 kj/mole for the acids, accurate to 0.03 − 0.04%,

‐ΔHliq. = 653.8 c + 292.6 kj/mole for the methyl esters, accurate to 0.02%.

The theoretical heat of esterification of a fatty acid with methanol at 25 °C, disregarding heats of solution and dilution, was calculated to be 3.8 ° 0.6 kj/mole, which can be compared with the value of 4.2 ° 0.3 kj/mole for the theoretical heat of esterification of acetic acid with ethanol at about 20 °C, determined directly by Mme Bérenger‐Calvet.
Correlations between molecular structure and mass spectra I.: An anomalous type of rearrangement ions found in the mass spectra of carboxylic acids and nitriles
Authors: Rol N. C.
Published: September 2010

An important type of rearrangement ions is common to the mass spectra of several classes of organic compounds, e.g. ketones, aldehydes, acids, nitriles, etc. For its explanation McLafferty proposed a six‐membered ring transition state through which a hydrogen atom was thought to be transferred.

In the spectra of certain branched acids and nitriles we have observed an additional type of rearrangement ions. In the case of the nitriles one must discriminate between the actual rearrangement ions CnH2n‐1N+ and the ions Cn+1H2n+1+, of nearly the same mass. With a mass spectrometer of high resolving power (A.E.I., MS 9) the presence of both types of ions was established; their relative abundances vary widely for different substances.

Although at first sight related to the McLafferty‐rearrangements, the newly found rearrangements are not readily explained in exactly the same way. They can be accounted for by a simple modification of McLafferty's scheme, involving a seven‐ or even eight‐membered ring transition state instead of the usual six‐membered one.
Solubility of aromatic hydrocarbons in aqueous sulfuric acid
Authors: Cerfontain H.
Published: September 2010

The solubilities of various aromatic hydrocarbons in aqueous sulfuric acid were determined at 25°. All hydrocarbons studied exhibit a minimum solubility in the 40‐70 wt‐% H2SO4 region.

UV and NMR studies indicate that with benzene the variation in solute‐solvent interaction with variation in sulfuric acid concentration is small. The variation of the benzene solubility is therefore rationalized in terms of variations in internal pressure of the sulfuric acid solvent. With dipolar hydrocarbons in aqueous sulfuric acid, solute‐solvent interaction is observed. Solute‐solvent interaction energies of some monoalkylbenzenes relative to benzene have been estimated.
The solubility of toluene and benzene in concentrated aqueous sulfuric acid; implications to the kinetics of aromatic sulfonation
Authors: Cerfontain H. , Telder A.
Published: September 2010

The solubility of benzene and toluene in aqueous sulfuric acid > 75 wt‐% has been determined at 5, 25 and 45°.

Molar heats of solution have been calculated. The benzene to toluene activity coefficient ratio is slightly greater than unity. The relatively large difference in activation entropy for sulfonation of the para‐position in toluene and a single position in benzene1 is therefore attributed mainly to differences in solvation of the transition states.
Mixed carboxylic acid anhydrides: IV. formic anhydride
Authors: Schijf R. , Scheeren J. W. , van Es A. , Stevens W.
Published: September 2010

Compound X2 found in formic acetic anhydride after disproportionation and in formic acid/carboxylic acid anhydride reaction mixtures was proved to be formic anhydride. This anhydride could be synthesized in 90% molar purity.
Studies on polypeptides IV: Syntheses and activities of some angiotensin‐like peptides
Authors: Schattenkerk Cecile , Havinga E.
Published: September 2010

The following heptapeptides and octapeptides have been synthesized: (des‐Asp1)‐L‐Arg2(NO2)‐Ile5‐angiotensin II, (des‐Asp1)‐D‐Arg2(NO2)‐Ile5‐angiotensin II, D‐Asp(NH2)1‐Ile5‐angiotensin II, D‐Asp(NH2)5‐D‐Arg2‐Ile5‐angiotensin II, Gly1‐D‐Arg2‐Ile5‐angiotensin II, Asp1(NH2)‐Cit2‐Ile 5−‐angiotensin II*. Possible structure‐activity relationships are discussed.
Conversion of δ‐lactones into γ‐lactones: Extension of the scope of the fittig reaction
Authors: de Jonge A. P.
Published: September 2010

The observations described in the literature that alkenoic acids by heating with 80% sulfuric acid (Fittig reaction) yield γ‐lactones have been confirmed. In addition it has appeared that besides the γ‐lactone a small percentage of δ‐lactone is formed.

Further it has been found that on heating δ‐lactones under the conditions of the Fittig reaction also γ‐lactones are obtained. By variation of the reaction conditions, γ‐ and δ‐lactones can be obtained in varying ratios.

For the quantitative analysis of a mixture of isomeric γ‐ and δ‐lactones, paper chromatography of the corresponding hydroxy‐acid anilides is perfectly practicable.
Studies in group iv organometallic chemistry. XX: Addition of Trialkyltin Hydrides to Substituted Acetylenes: The Structure of the Addition Products
Authors: Leusink A. J. , Marsman J. W. , Budding H. A.
Published: September 2010

The addition of trialkyltin hydrides to mono‐ and di‐substituted acetylenes has been studied more closely. The identity and geometry of the resulting 1:1 adducts have been established by means of GLC, IR and NMR spectroscopy, elementary analysis and degradation reactions.

Both terminal and non‐terminal addition of the trialkylstannyl group has been observed. Trans‐addition of the Sn‐H bond across the triple bond seems to occur mainly.
Mixed carboxylic acid anhydrides: V. Synthesis of alkyl formates
Authors: van Es A. , Stevens W.
Published: September 2010

The investigations into the esterification of primary, secondary and tertiary alcohols with formic acid/acetic anhydride reaction mixtures have been extended. The effect of various molar intake ratios of formic acid and acetic anhydride as well as the influence of temperature, solvents, and catalysts have been examined. The results obtained led to simple methods of synthesis of pure alkyl formates in high yields.
Investigations on sterols XXV: Synthesis and configuration at C‐20 of epimeric 20‐hydroxy‐9β,10α‐pregnane derivatives
Authors: van Kamp H.
Published: September 2010

The synthesis is reported of 20α‐hydroxy and 20β‐hydroxy‐9β,10α‐pregna‐4,6‐dien‐3‐one and their corresponding 6,7‐dihydro derivatives. The assignment of the configuration at C‐20 is based on alternative synthesis by Baeyer‐Villiger oxidation of the corresponding 20‐formyl compounds. Molecular rotation relationships and N.M.R. spectra are discussed.
The mannich condensation of sulfinic acids, aldehyde, and ethyl carbamate II.: The use of higher aldehydes
Authors: Engberts J. B. F. N. , Strating J.
Published: September 2010

α‐Aryl‐ and α‐alkyl‐N‐(sulfonylmethyl)urethanes have been prepared by a Mannich condensation of a sulfinic acid, an aldehyde, and ethyl carbamate. Three procedures for this reaction are discussed.