bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation and identification of α‐methylene‐butyrolactone, A fungitoxic substance from tulips
Authors: Bergman B. H. H. , Beijersbergen J. C. M. , Overeem J. C. , Sijpesteijn A. Kaars
Published: September 2010

A fungitoxic substance has been isolated from extracts from the white skins of tulip bulbs, from the fleshy bulb scales and from the flower pistils. The compound was identified as α‐methylenebutyrolactone.
Acetylenic thiolesters as a source of thioketenes
Authors: Wijers H. E. , van Ginkel C. H. D. , Brandsma L. , Arens J. F.
Published: September 2010

1‐Acetylthio‐1‐hexyne, magnified image, is cleaved by nucleophilic reagents. With primary and secondary amines, RR′NH (R = alkyl or aryl, R′  H or alkyl), N‐substituted acetamides CH3CONRR′ and N‐substituted thioamides C4H9CH2C(S)NRR′ are produced in good yields, the latter compounds presumably via the thioketene C4H9CHCS. In the case of ammonia, mainly acetamide and the polymer of the thioketene are obtained. Acethydrazide and 3,6‐dipentyl‐1,4 dihydro‐1,2,4,5‐tetrazine, I, have been isolated from the reaction mixture of acetylthiohexyne and hydrazine hydrate. Potassium amide, dissolved in liquid ammonia, converts acetylthiohexyne into hexynethiolate, C4H9CCSK (and acetamide); subsequent addition of ethyl bromide gives ethylthiohexyne, C4H9CCSC2H5, in excellent yield. If acetylthiohexyne is allowed to react with a mixture of ethanethiol and sodium ethanethiolate in dimethylformamide, the intermediate thioketene is trapped to produce the dithioester C4H9CH2C(S)SC2H5.
Activity coefficients of individual ions
Authors: Alfenaar M. , de Ligny C. L.
Published: September 2010

Existing methods for the estimation of the primary medium effect for individual ions are critically reviewed and an improved method for its estimation is developed.

By this method the primary medium effect of the hydrogen ion has been determined for the transfer from water to methanol‐water mixtures and methanol. The medium effect of the alkali and the halide ions are then also known. The accuracy of the values so obtained for the individual ions is of the same order as the accuracy of experimentally determined values for electroneutral combinations of ions.
Free radical additions. Part I: Free radical addition of cyclo‐octane to unsaturated compounds
Authors: van Bruggen E. , Boelens H. , Rijkens F.
Published: September 2010

Cyclo‐octyl radicals, generated by decomposition of di‐t‐butyl peroxide (DTBP) in cyclo‐octane, react with unsaturated compounds. The addition of cyclo‐octane to acrylic acid, crotonic acid, methyl vinylacetate or allyl alcohol yields the corresponding 1 : 1 adducts. Retention indices and NMR spectral data for these addition products are given.
Optical activity of symmetrically substituted acetic acids. Part II: The synthesis of alkyl‐substituted diphenylacetic acids
Authors: Akkerman O. S.
Published: September 2010

The synthesis of the substituted diphenylacetic acids, the stability against racemization of which was recorded in Part I, is described.
The absolute configuration of β‐hydroxyvaline
Authors: Beyerman H. C. , Maat L. , de Rijke D. , Visser J. P.
Published: September 2010

The optical rotatory dispersion spectra of the enantiomers of β‐methoxyvaline were measured between 200 and 400 nm. From the Cotton effect at 210 nm follow the absolute configurations, and consequently those of the derived hydroxy amino acids: D‐(‐)‐ and L‐(+)‐β‐hydroxyvaline.
The universal pH‐scale for solutions at different temperatures and in different solvents
Authors: de Ligny C. L. , Alfenaar M.
Published: September 2010

A universal acidity scale, holding for solutions at any temperature and in any solvent, is developed. It is based on the operational pH‐definition and relates the measured pH‐values to the change in chemical potential on transferring a proton from solution X to a hypothetical solution of unit proton activity at 25° in water.

This acidity scale is an extension of the universal pH‐scale for methanol‐water mixtures at 25° proposed by the authors1 and is closely related to the universal acidity scale for water at different temperatures, proposed by Aleksandrov and Lebed'.2 The disadvantage of the latter is that it does not lead to a simple, or easily applicable, physical significance of the measured acidities.
The system NbCl5‐Nb2O5: Part V the P‐T‐x space model and the thermodynamic properties of NbOCl3
Authors: Hart W.'T , Meyer G.
Published: September 2010

From the results of the vapour pressure measurements described in previous communications of this series1 and the determination of the compositions of the phases occurring in the different equilibria, the P‐T‐x space model for the binary system is derived. The P‐T and T‐x projections and the most important P‐x and T‐x sections are given. The thermodynamic constants of NbOCl3 are derived also from the results of the measurements described previously.
Complexes of ligands containing S  O: Parts IV and V. IV. Trimethylene sulfite as a ligand. V. ligand field spectra of cobalt(II) and nickel(II) compounds
Authors: van Leeuwen P. W. N. M. , Groeneveld W. L.
Published: September 2010

Three inorganic complexes of trimethylene sulfite (abbreviated tms) viz. Ni(tms)6(BF4)2, Co(tms)6(BF4)2 and Co(tms)6(ClO4)2 are reported. The analyses and X‐ray diffraction diagrams of the three isomorphous compounds are given.

In Part V the diffuse reflectance spectra are reported for complexes of the following sulfoxides: diphenyl, methyl phenyl, dimethyl, tetramethylene and pentamethylene sulfoxide, and trimethylene sulfite. Remarkable differences are found in the spectrochemical parameters in the solid state.
Structure of a thiopyran‐1,1‐dioxide
Authors: Boelema E. , Visser G. J. , Vos Aafje
Published: September 2010

An X‐ray diffraction study has shown the thiopyran‐1,1‐dioxide prepared by debromation of 2,3,5,6‐tetrabromotetrahydrothiopyran‐1,1‐dioxide with zinc to be α‐thiopyran‐1,1‐dioxide.
α‐Halogenovinyl sulfoxides: Re‐examination of the structure of some β‐halogenovinyl sulfoxides
Authors: Molenaar E. , Strating J.
Published: September 2010

The compounds obtained by dehydrohalogenation of α,β‐dihalogenated sulfoxides have the α‐halogenovinyl structure and not the β‐substituted structure previously assigned to them1−4.
Chemistry of acetylenic ethers. Part 90: Cyclotetramerization of ethynyl ethers to 1,3,5,7‐tetra‐alkoxycyclo‐octatetraenes. Syntheses of 3,5,7‐triethoxy‐2,4,6‐cyclo‐octatrienone and of 1,3,5,7‐tetra‐alkoxy‐2,6‐dioxa‐adamantanes
Authors: Braams J. F. H. , Bos H. J. T. , Arens J. F.
Published: September 2010

Ethoxyethyne and propoxyethyne are slowly tetramerized to 1,3,5,7‐tetra‐alkoxycyclo‐octatetraenes under the influence of alkali amides in liquid ammonia. By partial hydrolysis 1,3,5,7‐tetraethoxycyclo‐octatetraene (I) is converted into 3,5,7‐triethoxy‐2,4,6‐cyclo‐octatrienone (III). Treatment with acidified ethanol or methanol leads to 1,3,5,7‐tetraethoxy‐2,6‐dioxa‐adamantane (V) and 1,3,5,7‐tetramethoxy‐2,6‐dioxa‐adamantane (IV), respectively.
Protonation of halogen‐containing benzenes in HF‐SbF5. Part II.: PMR spectra of halotoluenium and halobenzenium ions
Authors: Brouwer D. M.
Published: September 2010

A number of halotoluenes and halobenzenes have been found to give stable benzenium ions in HF‐SbF5. The PMR spectra of these ions are reported. A mixture of all three possible stable cations was obtained with m‐chloro‐ and m‐bromotoluenes; of m‐fluorotoluene only two cations were formed in observable amounts. Likewise, both possible stable m‐dichlorobenzenium ions were observed, but only one m‐difluorobenzenium ion. Reversible line broadenings in the spectra of all these ions, and of 1,3,5‐trichlorobenzenium ion showed the occurrence of rapid intramolecular and/or intermolecular hydrogen exchange reactions at temperatures of 0° C or lower, depending on the cation. In the cases of o‐chloro‐ and o‐fluorotoluenium ions fast exchange reactions lead to coalesced signals at temperatures as low as −40° and 0°, respectively. Protonated fluoro‐benzene and chlorobenzene likewise give coalesced signals at −40°.
Amino‐substituted glyoximes and furoxans
Authors: Walstra P. , Trompen W. P. , Hackmann J. Th.
Published: September 2010

The preparation of some N,N′‐substituted diaminoglyoximes from dichloroglyoxime diacetate and primary and secondary amines, respectively is described.

The oxidation of the fully substituted diaminoglyoximes leads solely to the corresponding furoxans.
Lead chromium sulfide, PbCr2S4, and some isotypic compounds
Authors: Omloo W. P. F. A. M. , Jellinek F.
Published: September 2010

The compounds PbCr2S4, SrCr2S4, BaCr2S4, EuCr2S4, SrCr2Se4 and EuCr2Se4 have been prepared and characterized. The compounds are isostructural with a hexagonal structure; the unit‐cell dimensions of PbCr2S4 are: a = 21.411 Å; c = 3.478 Å c/a = 0.1624. PbCr2S4 is a ferrimagnetic semi‐conductor with a Curie temperature of 138°K.
NMR of hydrogen fluoride in the gas phase
Authors: Mackor E. L. , Maclean C. , Hilbers C. W.
Published: September 2010

NMR experiments in gaseous hydrogen fluoride are reported; somewhat surprisingly, both nuclei in the molecule give single lines instead of doublets, which means that rapid exchange reactions take place in the gas phase.

Line widths for hydrogen are smaller than 30 c/s; for fluorine the line width increases considerably at lower pressures. It is concluded that the relaxation mechanism of the fluorine spins is spin‐rotational interaction. The chemical shifts of both hydrogen and fluorine are strongly dependent on the pressure. This behaviour is discussed in terms of association of HF vapour to predominantly cyclic hexamers. The chemical shifts of the hydrogen fluoride monomer and hexamer in the vapour are +4.35 ± 0.15 and −1.20 ± 0.15 for hydrogen and +14.0 ± 1.1 and −2.45 ± 1.1 ppm, respectively, for fluorine from liquid HF, corrected for bulk diamagnetic susceptibility.
On the reactivity of organophosphorus compounds: Part IV. The alkaline hydrolysis of some O‐phosphylated 2‐pyridine oximes
Authors: van Hooidonk C. , Kraaij G. W. , Ginjaar L.
Published: September 2010

The rates of alkaline hydrolysis of a number of O‐phosphylated 2‐pyridine oximes, C5H4NC(R1)NOP(O)R2R3, at different temperatures have been determined. The second‐order rate constants and the values of ΔH* and ΔS* are reported. Two parallel pathways of hydrolysis are observed: a nucleophilic substitution reaction on phosphorus (SN2P) generating the oxime and the parent acid and an elimination reaction of the Beckmann type (E2 or ElcB) producing the nitrile and the parent acid. The effects of the groups R1, R2 and R3 on the rates of substitution and elimination are discussed.
Properties of diazosulfonates: Part V. The effect of substituents on spectra and dissociation of 4‐dimethylaminobenzenediazosulfonate
Authors: van Beek L. K. H. , Boven J. , Helfferich J.
Published: September 2010

The absorption spectra of the substituted 4‐dimethylaminobenzenediazosulfonates in aqueous solution exhibit at least five bands in the region 210‐500 nm. Of these, the low‐intensity n → π* absorption is hidden in the π → π* band, which is found between 355 and 435 nm depending on type and positions of the substituents. A transition near 210 nm is assigned Φ → Φ*, which makes it likely that another band located in between the very intense Φ → Φ* and π → π* absorption is π → Φ*. The dissociation in aqueous solution is considerably reduced by substitution of electron‐attracting groups at positions 2 and 3 of the benzene ring. The overall dissociation constants of a number of mono‐ and di‐substituted benzene‐trans‐diazosulfonates were found to obey the Hammett equation with a reaction constant of 6.3 (± 0.2). The applicability of the Hammett equation indicates that the overall dissociation constant is proportional to that of the cis isomer.

A general new method is given for the synthesis of a substituted 4‐dimethyl‐amino‐nitrobenzene from the relevant 4‐chloro‐nitrobenzene derivative.
Electron diffraction by gases: The molecular structure of bicyclo[2.2.1]heptane
Authors: Dallinga G. , Toneman L. H.
Published: September 2010

The structure of bicyclo[2.2.1]heptane has been investigated by means of electron diffraction of the vapour. The results are compared with other electron measurements, with X‐ray singlecrystal work on derivatives, and with theoretical calculations. Some interesting facts emerge, but a complete, accurate and unambiguous structure is not produced by the diffraction techniques.
Electron diffraction by gases: The molecular structure of bicyclo[2.2.1]hepta‐2,5‐diene
Authors: Dallinga G. , Toneman L. H.
Published: September 2010

The structure of bicyclo[2.2.1]hepta‐2,5‐diene has been investigated by means of electron diffraction of its vapour. The results are compared with those of other electron diffraction and X‐ray investigations and with theoretical calculations. It appears that in this molecule the sp2‐sp3 and the sp3‐sp3 carbon‐carbon bonds are very nearly equal.
Aromatic sulfonation 20: The sulfonation of some chlorobenzenes with sulfur trioxide in nitromethane as solvent
Authors: Bosscher J. K. , Cerfontain H.
Published: September 2010

The sulfonation of chlorobenzene andp‐dichlorobenzene with sulfur trioxide in nitromethane as solvent has been studied. The main reaction products are arenesulfonic anhydride and probably arenepyrosulfonic acid. Withp‐dichlorobenzene as substrate the amount of diaryl sulfone is undetectably small; with chlorobenzene it is < 1‐mole % relative to the converted substrate. The sulfonation is of the first order with respect to the substrate and of the second order with respect to sulfur trioxide. For each mole of converted substrate two moles of sulfur trioxide are consumed. The sulfonation ofp‐dichlorobenzene proceeds without a primary kinetic isotope effect of hydrogen.

It is suggested that the sulfonation proceeds via 1‐arenonium‐1‐sulfonate and 1‐arenonium‐1‐pyrosulfonate as the subsequent reactive intermediates, with the formation of the latter intermediate as the rate‐limiting step. The kinetics of the formation of 4,4′‐dichlorodiphenyl sulfone are compatible with a mechanism in which the speciesp‐ClC6H4S3O9H is the effective sulfonylating entity.

The literature on aromatic sulfonation with sulfur trioxide in aprotic solvents is critically reviewed.
Electron diffraction by gases: The molecular structure of spiropentane
Authors: Dallinga G. , van der Draai R. K. , Toneman L. H.
Published: September 2010

The molecular structure of spiropentane has been redetermined from electron diffraction by the vapour. The difference of 0.05 Å found between the two non‐equivalent carbon‐carbon bond lengths is in agreement with the expectation based on the results of an MO calculation.
Natural coumarins. Part X.: Isoimperatorin, a further constituent of the fruits of Ammi Majus L
Authors: Abu‐Mustafa E. A. , El‐Bay F. K. A. , Fayez M. B. E.
Published: September 2010

In addition to the previously known coumarin constituents (xanthotoxin, imperatorin, bergapten, isopimpinellin and marmesin) of Ammi majus L. fruits, a further product has been isolated. On the basis of chemical and physical evidence, the new component was proved to be isoimperatorin (VII).
Free radical additions. Part II: Free radical cyclization of citronellol (Short communication)
Authors: van Bruggen E.
Published: September 2010

Citronellyl radicals generated by abstraction of a C1‐hydrogen atom in the presence of di‐t‐butyl peroxide (DTBP) in citronellol undergo cyclization to yield a mixture of menthols.
Reactions of organometallic compounds with terminal epoxides. Part I. Reaction of various magnesium compounds with propylene oxide
Authors: Schaap A. , Arens J. F.
Published: September 2010

The reaction of propylene oxide with Mg‐compounds has been investigated systematically. Variations involved alkyl group, halide, presence of salts, solvent, ratio of reactants, reaction period and temperature.
Some reactions with 1,1‐bis(alkylthio)‐2‐alkynes
Authors: Wildschut G. A. , van Boom J. H. , Brandsma L. , Arens J. F.
Published: September 2010

1,1‐Bis(alkylthio)‐2‐alkynes RCH2CCCH(SC2H5)2 (I) (with R  H or alkyl) can be metallated with alkali metal amides in liquid ammonia or with butyllithium in ether or tetrahydrofuran. Subsequent hydrolysis affords a mixture of 1 and a 1,1‐bis(alkylthio)‐1,2‐alkadiene RCH2CH  CC(SC2H5)2 (II); a similar result is obtained starting from II. The ratio of I and II depends on the metallating agent and on the solvent. Sodium ethoxide in liquid ammonia or in ethanol converts I into II completely.

Alkylation of metallated I or II with alkyl iodides gives the products RCH2C  CC(R′)(SC2H5)2 (IV) and traces of RCH2C(R′)CC(SC2H5)2(V).

Reaction with allyl bromide or with chloromethyl ethyl ether leads to the formation of RCH2CCC(CH2CH CH2)(SC2H5)2 (VI) and RCH2CCC(CH2OC2H5)(SC2H5)2 (VII). Acetone reacts to give the carbinol RCH2CCC[C(CH3)2OH](SC2H5)2 (VIII) as the sole product.
Charge fluctuations in isoionic protein solutions. Determination of the quantity S = (¯z2)½ by means of conductivity measurements and hydrogen ion titrations
Authors: de Bruin S.H. , van Os G.A.J.
Published: September 2010

On theoretical grounds it must be expected, that the electrical charge of protein molecules fluctuates around a mean value. In this paper the determination of the standard deviation of the charge from this; mean value in isoionic protein solutions is described. The standard deviation was measured in two independent ways, viz. from conductivity measurements and from the slope of the hydrogen ion titration curves. The proteins investigated were bovine carboxy‐hemoglobin, bovine methemoglobin, horse heart metmyoglobin and bovine serum albumin.
Synthesis and stereochemistry of spiro‐dihydropyran derivatives derived from bicyclo[2.2.1]heptane
Authors: de Boer Th. J. , van Velzen J.C. , Kruk C.
Published: September 2010

The addition of acrolein to norcamphene leads to an exo‐oxa spiro compound (Scheme 1, VIa). The corresponding endo‐isomer VIb can be obtained from norbornanone X and methoxybutenyne XIII via the sequence of reactions outlined in Scheme 2. Because the steric course in some crucial steps is known, the endo structure of VIb can be established.

An alternative route leading to the exo‐oxa. spiro compound IXa, starting with norbornanone is given in Scheme 3. Another route to predominantly endo‐oxa compounds from norbornanone is given in Scheme 4.
Dialkylethynylphosphine oxides; synthesis and reactions
Authors: Hagens W. , Bos H.J.T. , Voskuil W. , Arens J.F.
Published: September 2010

Dimethyl‐ and dibutyl‐ethynylphosphine oxide R2P(O)C ≡ CH with R = CH3 and n‐C4M9, respectively, have been prepared from the corresponding dialkylphosphinic chlorides.

Reactions of (C2H5)2NH, (CH3)2NH2, NaOCH3, NaOC2H5, NaSC2H5, HCl and HI with these ethynylphosphine oxides afforded 1: 1 adducts of the general formula R2P(O)CH = CHY. With the exception of alkoxide the addition occurred in the trans fashion yielding the cis compounds, but several adducts thermally rearranged to the trans isomers.

As a side reaction with Na OC2H5, nucleophilic substitution at the phosphorus atom was observed.

The stereochemistry of the reactions was established by NMR spectroscopy. The influence of substituents on coupling constants was studied.
The β‐pinene‐acrolein adduct and its acid‐catalysed cyclization
Authors: Kruk C. , Velzen J. C. V. , de Boer Th. J.
Published: September 2010

Thermal addition of acrolein to β‐pinene leads mainly to the unsaturated aldehyde I and, in small amount, to the spiro compound II. Heating of I with dilute acid yields 6‐isopropyltetralin (IV) and the tricyclic diol V, the latter being favoured at very low acid concentrations. Oxidation of this diol yields the ketol VI with a negative Cotton‐effect and the diketone VII with a positive Cotton‐effect, both in accordance with the suggested stereo‐structure.
On the synthesis of cephalosporin antibiotics (III). α, β‐substituted butenolides and α,β‐substituted γ‐butyrolactones via Erlenmeyer condensations
Authors: Tan H. S. , Reinhoudt D. N. , Beyerman H. C.
Published: September 2010

A synthesis of α, β‐substituted butenolides and of α, β‐substituted γ‐butyrolactones, starting from 1, 3‐dihydroxyacetone and a number of N‐acylglycines, by an Erlenmeyer condensation is described.

The scope and limitations of the condensation were studied.
Synthesis and antifungal activity of some carbohydrate and amino acid derivatives of dimethyldithiocarbamic acid and of pyridine‐2‐thiol 1‐oxide
Authors: Pluijgers C. W. , Berg J. , Thorn G. D.
Published: September 2010

The synthesis of a number of carbohydrate and amino acid derivatives of dimethyldithiocarbamic acid and of pyridine‐2‐thiol 1‐oxide is described. The antifungal activity of the compounds and their activity against cucumber scab (Cladosporium cucumerinum) are given in tabular form.
Vibrational‐Spectra of some indium compounds
Authors: Brinkmann F. J. J. , Gerding H.
Published: September 2010

Solid state Raman‐spectroscopic results are communicated for: In2Cl3, In5Cl9, InCl2, InCl3, InCl3 · PCl51, InCl3 · NH4Cl, InCl3 · N(C2H5)4Cl, InCl3 · 3 NH4Cl and InCl3 · 3 TlCl.

The melt of InCl2 has been studied too.

Infrared absorption spectra, mostly in the range 240‐700 cm−1, have been determined for the majority of the compounds mentioned above.

A detailed study of the binary system In ‐ InCl3 in the range InCl1.75 to InCl2.10 has been made.
Chemistry and spectroscopy in strongly acidic solutions. Part XXV: Formation and properties of 1,2,3,4,5,6‐hexamethylcyclohexenyl cations
Authors: Hogeveen H. , Gaasbeek C. J. , Volger H. C.
Published: September 2010

1,2,3,4,5,6‐Hexamethylcyclohexenyl cations are obtained on protonation of 1,2,3,4, 5endo, 6endo‐hexamethylbicyclo[2.2.0]hexene and of cis‐1,2,3,4,5,6‐hexamethylcyclohexa‐1,3‐diene. The structure of the ions was proved unambiguously by the chemical shifts and coupling constants of the NMR signals, by deuterium labelling experiments and by their chemical reactivity.

The mechanism of the formation of the ions is discussed.
Isomerization reactions occurring on alkylation of benzene with some branched long‐chain 1‐alkenes
Authors: Nooi J. R. , Muller J. J. , Testa M. C. , Willemse S.
Published: September 2010

Benzene was alkylated successively with a mixture of 2‐methyl‐1‐octene and 2‐methyl‐2‐octene, with 2‐butyl‐1‐octene, 3,7‐dimethyl‐1‐octene, 10‐methyl‐1‐undecene and 3,3‐dimethyl‐1‐undecene, using sulfuric acid and aluminium chloride as catalysts. In some cases, a considerable methide shift occurred.

With sulfuric acid, there is a considerable preference for the formation of tertiary alkylbenzenes, even if the tertiary carbon atom is far removed from the double bond.

Under the conditions used, aluminium chloride shows less preference for the formation of tertiary alkylbenzenes. The yields are low when, in the early stage of the reaction, a tertiary carbonium‐ion type intermediate is formed. Particularly tertiary alkylbenzenes are unstable under alkylation conditions in the presence of aluminium chloride: dealkylation and isomerization to secondary alkylbenzenes occur.
The chemistry and fungicidal and phytotoxic properties of arylsulfonyl‐, arylsulfinyl‐, and arylthio‐alkyl thiocyanates
Authors: Dolman H. , Tempel A. , Koopman H. , Wellinga K. , Hamminga D.
Published: September 2010

The synthesis and fungicidal and phytotoxic properties of a large number of arylsulfonyl‐, arylsulfinyl‐, and arylthio‐alkyl thiocyanates are described and discussed.
Nitromethane as a ligand. Part I: Complexes with some divalent metals and the hexachloroantimonate anion
Authors: Driessen W. L. , Groeneveld W. L.
Published: September 2010

A series of new complexes is reported with nitromethane as a ligand: viz. [M(CH3NO2)6]2+[SbCl6]2− where M is Mg(II), Ca(II), Sr(II), Mn(II), Fe(II), Co(II), Ni(II), and Zn(II).

The compounds have been identified by chemical analysis and with the aid of physical measurements.

No shift in the N → O stretching frequencies has been observed. The NO2 rocking mode (B1) shifts to higher frequencies.

Ligand field spectra for the Co(II) and Ni(II) compounds are investigated. Values for Dq and B are reported and the ligand is placed in the spectrochemical and nephelauxetic series.

It is concluded that complexes of nitromethane can serve as precursors of coordination compounds of other weakly nucleophilic ligands.
Extraction of platinum group metals by high molecular weight amines (H.M.W.A.): A study of Pt(IV)‐HCI system
Authors: Khattak M. A. , Magee R. J.
Published: September 2010

The distribution of Pt(IV), between aqueous hydrochloric acid solutions and various High Molecular Weight Amines in organic solvents has been studied and the effects of HCl concentration, the type of amine and various organic solvents investigated. Spectrophotometric studies were carried out on the aqueous Pt(IV) solution in hydrochloric acid solution and on the extracted species in the organic phase. Diffuse reflectance studies on the complexes were also carried out and evidence is presented to support the conclusion that the extracted species is the hexachloroplatinate(IV) ion.
Mechanism of reactions of α‐ diazosulfones. Part V. Substituent effects in the acid‐catalysed hydrolysis of arenesulfonyldiazomethanes
Authors: Engberts J.B.F.N. , Zuidema G. , Zwanenburg B. , Strating J.
Published: September 2010

The synthesis of the α‐diazosulfones m‐XC6H4SO2CHN2 (X = CH3O, CH3, Cl, CF3 and NO2) by the method of van Leusen and Strating is described. The pseudo first order rate constants for the acid‐catalysed hydrolysis of these a‐diazosulfones and those of p‐XC6H4SO2CHN2 (X = CH3O, CH3, H, Cl, NO2) in 40% (v/v) dioxane‐water at 25° have been correlated by the Hammett qσ equation. The deviation found for the p‐CH3O‐derivative is discussed. A linear correlation has been found between the logarithm of the rate constants and the frequencies of the infrared absorption of the diazo group at about 2100 cm−1. This relationship between rate data and infrared frequencies can be extended to the acid‐catalysed solvolysis of other types of aliphatic diazo compounds.
Complexes with ligands containing nitrile groups Part XI: The formation of chloromercurate(II) anions with mono‐ and di‐valent cations in acetonitrile
Authors: Reedijk J. , Groeneveled W.L.
Published: September 2010

Twenty new compounds of the general formula M(CH3CN)mn+(anion)n− are described. In this formula M = (C2H5)4N, Li, Mg, Ca, Mn, Fe, Co, Ni, Cu, and Zn, n = 1 or 2, m = 0‐8, and the anions are (HgpCl2p+q)q−, in which p = 1‐5 and q = 1 or 2.

These compounds are prepared by chloride‐ion transfer reactions between MCln and HgCl2 in acetonitrile. The process is followed conductometrically for some cases.

The compounds are identified and characterized by chemical analyses, ligand‐field spectra, infrared spectra, and Raman spectra. Both tetrahedral and linear coordinated chloromercurate(II) anions are found to be present in the solid compounds.
Isomerization of cyclic olefins in basic media. Part 2: The degradation of [14C]‐cyclopentene, [14C]‐cyclohexene and [14C]‐cycloheptene
Authors: Tjan S.B. , Steinberg H. , de Boer Th. J.
Published: September 2010

Various methods of selective degradation of [14C]‐cyclopentene, [14C]‐cyclohexene and [14C]‐cycloheptene are described, which render it possible to determine the specific activity of each ring carbon atom. The synthesis of [1‐14C]‐cycloheptene from [l‐14C]‐cyclohexanone is described.
The synthesis of substituted bicyclo[3.2.1]octa‐2,6‐dienes
Authors: Klumpp G. W. , Barnick J. W. F. K. , Veefkind A. H. , Bickelhaupt F.
Published: September 2010

Bicyclo[3.2.1]octa‐2,6‐diene‐ax‐ and ‐eq‐4‐carboxylic acids (IIIa) have been prepared via Knoevenagel condensation of bicyclo[3.1.0]hex‐2‐ene‐6‐endo‐carbaldehyde (Ia). Synthesis and properties are reported of endo‐4‐t‐butoxy‐bicyclo[3.1.0]hex‐2‐ene‐6‐endo‐carbaldehyde (Ib). This aldehyde has been converted to endo‐8‐t‐butoxybicyclo[3.2.1]octa‐2,6‐diene (IIIb) and to endo‐8‐t‐butoxybicyclo[3.2.1]octa‐2,6‐diene‐ax‐ and ‐eq‐4‐carboxylic acids (IIIc) respectively via Wittig methylenation and Knoevenagel condensation.
Acid‐catalyzed ring closure of 1‐methoxy‐ or 1‐methylthio‐1‐(α‐ or β‐hydroxyalkyl)allenes: Formation of 3,8‐dimethoxy‐1,6‐dioxacyclodeca‐3,8‐dienes and 4‐methylthio‐5,6‐dihydro‐2H‐pyrans
Authors: Hoff S. , Brandsma L.
Published: September 2010

Treatment of 1‐(α‐hydroxyalkyl‐1‐methoxyallenes CH2CC(OCH3)C(OH)R1R2 (I, with R1 and R2H, alkyl or (CH2)5‐) with a catalytic amount of p‐toluenesulfonic acid in tetrahydrofuran gives 3,8‐dimethoxy‐1,6‐dioxacyclodeca‐3,8‐dienes (VI) in low to moderate yield.

The same treatment of 1‐(β‐hydroxyethyl)‐1‐methylthioallenes RCH = C=C(SCH3)CH2CH2OH (IX, with R = H or n‐C3H7) produces 4‐methylthio‐5,6‐dihydro‐2H‐pyrans (X and XI) in good yields.

Addition of gaseous hydrogen chloride to methoxypropadiene gives ClCH2CHCHOCH3 (VIII).
Alkyl 1,1‐dialkoxy‐alkane‐ and ‐arene‐carboxylates. Part III: Mixed orthoformates
Authors: Scheeren J. W. , Stevens W.
Published: September 2010

The reaction of ROH and RSH (R = alkyl or aryl) with methyl diethoxyacetate leads to an easy synthesis of mixed orthoformates. In view of the contradictory results reported in the literature the disproportionation of mixed orthoformates was also studied.
A stereospecific synthesis of 4‐oxo‐2trans‐hexenal
Authors: Ward J. P. , van Dorp D. A.
Published: September 2010

4‐Oxo‐2trans‐hexenal is an odoriferous substance secreted by certain arthropods and it has also been described as present in soyasauce. It was synthesized as follows: reaction of propanal with the Grignard derivative of 1,1‐diethoxy‐2‐propyne to give 1,1‐diethoxy‐4‐hydroxy‐2‐hexyne, and reduction of the acetylenic bond with sodium in liquid ammonia to 1, 1‐diethoxy‐4‐hydroxy‐2trans‐hexene; oxidation with active manganese dioxide and acid hydrolysis gave the title compound in 96% purity (GLC). This synthesis offers a useful alternative to that described in the literature, which gives a mixture of the cis and trans isomers.
C‐Nitroso compounds: Part. XI. Trans‐azodioxycyclohexane (dimeric nitrosocyclohexane) by photochemical nitrosation of cyclohexane with alkyl nitrites
Authors: Mackor A. , Veenland J. U. , de Boer Th. J.
Published: September 2010

The photonitrosation of cyclohexane by tertiary butyl nitrite has been studied as a model system for the photochemical reaction between alkyl nitrites and hydrocarbons. The products are trans‐azodioxycyclohexane (trans‐dimeric nitrosocyclohexane) and a minor amount of cyclohexanone oxime, together in 81 % yield.

Most of the trans‐dimer is formed via the cis‐dimer, which can be isolated at low temperature. It is shown that optimal conditions for this reaction involve the use of a tertiary alkyl nitrite in low concentration, wavelengths around 400 nm and temperatures slightly below room temperature.

The free radical mechanism of this reaction is supported by electron spin resonance spectroscopy.
Synthesis of methyl DL‐13‐hydroxy‐9cis‐octadecenoate and methyl DL‐19‐hydroxy‐allcis‐8,11,14‐eicosatrienoate
Authors: Ward J. P. , van Dorp D. A.
Published: September 2010

When methyl vernolate was treated with BF3 etherate in benzene and the reaction product chromatographed on silica gel, the first eluted product contained methyl 13‐oxo‐9cis‐octadecenoate, contaminated with some dimers and polymers. Reduction with NaBH4 and re‐chromatography produced pure methyl DL‐13‐hydroxy‐9cis‐octadecenoate.

Methyl DL‐19‐hydroxy‐all cis‐8,11,14‐eicosatrienoate was prepared by extension of the carbon chain of 5‐chloro‐2‐pentanone, as acetal, by two 2‐propynyl units to 10‐oxo‐2,5‐undecadiynol. The corresponding bromo‐compound was acetalized and coupled with the di(bromomagnesium) derivative of 8‐nonynoic acid. Methyl 19‐oxo‐8,11,14‐eicosatriynoate was hydrogenated with Lindlar's catalyst and the oxo‐trienoate obtained was reduced with sodium borohydride. The disproportionation of 2‐(2‐hydroxyethoxy)tetrahydrofuran, a by‐product at one stage, is also described.
Isomerization of the bicyclo[5.1.0]octadienyl anion: (Short communication)
Authors: Kloosterziel H. , Zwanenburg E.
Published: September 2010

NMR spectroscopy has revealed that the bicyclo[5.1.0]octadienyl anion 2 isomerizes by opening of the three‐membered ring and a 1,2 shift of hydrogen to the 1,6‐methanoheptatrienyl anion 3. The symmetry‐forbidden electrocyclic ring opening of 2 to the cyclo‐octatrienyl anion 5 does not occur. Experiments with cyclo‐octa‐1,3,5‐triene showed that 5 is unstable relative to disproportionation into cyclo‐octatriene and cyclo‐octatetraenyl dianion.
Action of potassium amide on 6‐substituted derivatives of 2‐bromopyridine in liquid ammonia
Authors: Streef J. W. , den Hertog H. J.
Published: September 2010

In continuation of previous studies on the reactions of 2‐bromo‐6‐ethoxy‐, 2‐bromo‐6‐methyl‐ and 2,6‐dibromopyridine with potassium amide in liquid ammonia, aminations of twelve other 2‐bromopyridines substituted at the 6‐position, i.e. 6‐amino‐, 6‐anilino‐, 6‐amidocarbonyl‐, 6‐(N‐methylanilino)‐, 6‐phenyl‐, 6‐(2′‐pyridyl)‐, 6‐phenoxy‐, 6‐(p‐ethoxyphenoxy)‐, 6‐(m‐ethoxy‐phenoxy)‐, 6‐(p‐fluorophenoxy)‐, 6‐chloro‐ and 6‐nitro‐2‐bromopyridine were investigated.

The following reaction types were observed:

Substitutions producing 2‐amino derivatives (from all starting substances except 6‐amino‐, 6‐bromo‐, 6‐chloro‐ and 6‐nitro‐2‐bromopyridine).

Cine‐substitutions producing 4‐amino derivatives (from 6‐methyl‐, 6‐ethoxy‐, 6‐phenoxy‐, 6‐(p‐ethoxyphenoxy)‐, 6‐(m‐ethoxyphenoxy)‐ and 6‐(p‐fluorophenoxy)‐2‐bromopyridine).

Ring transformations yielding 6‐substituted 2‐methylpyrimidines by fission of the 3,4‐carbon bond (from 6‐phenyl‐, 6‐(2′‐pyridyl)‐, 6‐phenoxy‐, 6‐(p‐ethoxyphenoxy)‐, 6‐(m‐ethoxyphenoxy)‐, 6‐(p‐fluorophenoxy)‐ and 6‐chloro‐2‐bromopyridine; from 2,6‐dibromopyridine).

Replacement of the 6‐substituent producing the 6‐amino compound (from 2‐bromo‐6‐nitropyridine).

Ring fission yielding 1, 3‐dicyanopropene by cleavage of the N —C6 bond (from 6‐amino‐2‐bromopyridine).

The mechanisms of the reactions studied are discussed. In this connection the aminations of 2,6‐dichloro‐, 2,6‐difluoro‐ and 2‐amino‐6‐fluoropyridine were examined too.
Conformation of non‐aromatic ring compounds: Part 56. The conformational properties of cis‐2‐halogeno‐4‐t‐butylcyclohexanones
Authors: Buys H. R. , Giesen M. T. , Havinga E.
Published: September 2010

The dipole moments and vicinal coupling constants of cis‐2‐bromo‐, cis‐2‐chloro‐ and cis‐2‐fluoro‐4‐t‐butylcyclohexanone have been determined in several solvents, in order to investigate the conformational homogeneity of these compounds. The dipole moments show a small solvent‐dependence, which is not reflected in the coupling constants. The results can be explained satisfactorily on the assumption that in the solutions only the chair form (with an equatorially oriented halogen atom) occurs.
N,N′‐disubstituted‐5,5′‐diamino‐3,3′‐bi‐1,2,4‐oxadiazoles
Authors: Witteveen A. J. , Trompen W. P. , Hackmann J. Th.
Published: September 2010

The preparation of some N,N′‐disubstituted‐5,5′‐diamino‐3,3′‐bi‐1,2,4‐oxadiazoles from dichloroglyoxime diacetate and 1,1,3,3‐tetrasubstituted guanidines is described. Evidence for the structure is given by spectroscopic data and an independent synthesis.
C‐nitroso compounds. Part XIII: Monomeric nitroso compounds by photochemical nitrosation of branched‐chain hydrocarbons with tert‐butyl nitrite
Authors: Mackor A. , de Boer Th. J.
Published: September 2010

The photochemical nitrosation with t‐butyl nitrite of some branched‐chain hydrocarbons, containing tertiary hydrogen atoms leads to the formation of monomeric nitroso compounds in yields up to 78%, when a special Soxhlet technique is employed. The use of wavelengths around 400 nm is essential for this reaction.
Ester interchange using molecular sieves
Authors: Roelofsen D. P. , de Graaf J. W. M. , Hagendoorn J. A. , Verschoor H. M. , van Bekkum H.
Published: September 2010

Ester interchange reactions using type A molecular sieves which selectively adsorb the displaced alcohol, have been shown to proceed practically to completion. Examples are given which cover a number of starting esters, displacing alcohols, experimental procedures, solvents, and cationic forms of the molecular sieves. Several new t‐butyl esters were obtained and characterized.

Equilibrium constants were measured and rate studies made for several representative reactions.

The interaction of sodium and potassium isopropoxide catalysts and sieves has also been investigated. Both cation exchange with the sieves and adsorption of alkoxide after the addition of methyl alcohol have been observed. Interesting differences have been found between 3A, 4A, and 5A sieves.

The interfering dehydration of t‐butyl alcohol has been studied with different molecular sieves of type A. The influence of traces of water and triethylamine on the dehydration has been investigated.
Photoreaktionen aromatischer Verbindungen. XIX Photochemische Umwandlung von Nitronaphthalin in Chlornaphthalin
Authors: Frśater Gy. , Havinga E.
Published: September 2010

1‐Nitronaphthalene, 2‐methyl‐1‐nitronaphthalene (and probably also other 1‐nitronaphthalenes) upon illumination in media such as alkylchlorides, hexane/HCl, acetic acid/HCl undergo a substitution reaction yielding the 1‐chloro‐naphthalenes. Yields are high arid in spectroscopic dilution the reaction proceeds cleanly to practically 100% conversion. The reaction seems to belong to a new type of aromatic photosubstitution. In the case of nitrobenzenes it was not observed and with 2 nitronaphthalene it proceeded at a low rate only.
Preparation of 5,6‐Dimethylazulene and 5,6‐Dimethyl‐2‐Indanylacetic acid
Authors: Ward J. P. , Frost D. J.
Published: September 2010

5,6‐Dimethylazulene was prepared from 5,6‐dimethylindan by the diazoacetic ester method. Methyl 5,6‐dimethyl‐2‐indanylacetate was also obtained, and its structure determined from its 220 MHz NMR spectrum.
Formation of open anions from Dihydro‐Oxepin
Authors: Kloosterziel H. , van Drunen J. A. A.
Published: September 2010

Reaction of 2,3‐dihydro‐oxepin 1 with potassium amide in liquid ammonia yields, as revealed by NMR spectroscopy, the trans‐2,cis‐3,trans‐4,cis‐5 7‐oxaheptatrienyl anion 3, which is of fair configurational stability. The barriers for rotation in the oxaheptatrienyl anion are discussed.
Hindered rotation in diphenylmethane derivatives. Part III. A comparison of NMR kinetic studies with the results of racemization measurements
Authors: Akkerman O. S.
Published: September 2010

The NMR spectra of alkyl‐substituted diphenylmethane derivatives have been measured. In each compound investigated all chemically equivalent protons or group of protons were magnetically non‐equivalent due to hindered rotation. The activation parameters for the rotation of the phenyl groups in 2,4,2′,4′‐tetra‐tert. butyl‐6,6′‐dimethyldiphenylacetic acid were determined from variable temperature NMR experiments and were found to be in good agreement with the activation parameters for the racemization. Due to decomposition no kinetic measurements could be made on the benzhydrols and the benzhydryl methyl ethers.
Hydrogen bonding properties of α‐Diazosulfones and α‐Diazoketones
Authors: Engberts J. B. F. N. , Zuidema G.
Published: September 2010

IR and NMR spectral evidence indicates that α‐diazosulfones, RSO2CHN2 (I), and α‐diazoketones, RCOCHN2 (II), donate and accept protons in hydrogen bonding. The proton donor properties involve the methine proton as the donor site. The proton acceptor site is the sulfonyl group for α‐diazosulfones and the carbonyl moiety for α‐diazoketones. Using phenol as a donor molecule, OH stretching frequency shifts, Δν, have been measured for the α‐diazosulfones Ia‐Ig and the α‐diazoketones IIa‐IIf. Substituent effects on Δν values are modest for Ia‐Ig but more pronounced for IIa‐IIf. Compared with α‐diazoketones, α‐diazosulfones are stronger proton donors but weaker proton acceptors in hydrogen bonding.
Studies on polypeptides. Part X: Synthesis of 1‐13[10‐Homoarginine, 13‐Leucine] bovine pancreatic ribonuclease by combined solid‐phase and classical methods
Authors: Visser S. , Kerling K. E. T. , Havinga E.
Published: September 2010

Merrifield's solid‐phase method was applied to the synthesis of all‐L‐glutamyl‐homoarginylglutaminylhistidylleucine. Azide coupling in solution with all‐L‐Nα, Nϵ‐di‐t‐butoxycarbonyllysyl‐γ‐t‐butylglutamylthreonylalanylalanylalanyl‐Nϵ‐benzyloxycarbonyllysylphenylalanine hydrazide, also prepared on a solid support

S. Visser, J. Roeloffs, K. E. T. Kerling and E. Havinga, ibid. 87, 559 (1968).

, resulted in the N‐terminal tridecapeptide sequence of bovine pancreatic ribonuclease in which homoarginine and leucine replace arginine‐10 and methionine‐13, respectively.
Photoreactions of aromatic compounds. Part XX: The photosubstitution of nitronaphthalenes in alkaline media
Authors: van Henegouwen G. M. J. Beijersbergen , Havinga E.
Published: September 2010

The photoreactions of some methoxynitro‐, dimethoxynitro‐ and dinitronaph‐thalenes in alkaline medium are described. From the reactions observed (substitution of OCH3 or NO2 by OH) it appears that in the excited state of the naphthalene derivatives a nitro group in the one ring exerts a definite activating influence also on positions in the other ring. In these reactions specific “meta‐activation” was established.
Investigations on sterols. Part XXXVI: Synthesis of steroidal: Spirolactones with a Reformatsky reaction
Authors: de Bruin O. A. , Botterman J. , Westerhof P.
Published: September 2010

17‐Oxo steroids in a Reformatsky reaction with the ethyl ester of γ‐bromo‐β‐ethoxycrotonic acid gave rise to isomeric pairs of 17‐spirolactones. The spirolactone moiety of these compounds has been modified and related to that of known spirolactones.
Pyrazoles and imidazoles as ligands. Part IV. Ligand‐field spectra of tetragonal coordination compounds containing the ligand 3(5)‐methylpyrazole
Authors: Reedijk J.
Published: September 2010

Ligand‐field spectra of compounds with the formula M(anion)2(MPZ)4 in which MPZ is 3(5)‐methylpyrazole are discussed. The metal ions under investigation are Mn, Fe, Co, Ni and Cu(II), and the anions are NO3−, Cl−, Br−, I−, ClO4− and BF4−.

The spectrochemical parameters Dqxy, B, Ds and Dt are calculated from the spectral data for a number of isomorphous compounds. The alterations of these parameters are discussed as a function of the metal ions and the anions. Compared with other tetragonal compounds the distortion from octahedral symmetry in the present compounds is quite large. The origin of this strong tetragonal distortion seems to be the hydrogen‐bond formation between the coordinated ligands and the coordinated anions, weakening the metal‐anion bond in the z‐direction.

The tetragonal species M(anion)2(MPZ)4 also have been investigated in solutions of acetone, nitromethane and methylene chloride. For some compounds this tetragonal species also exists in solution, but for some other compounds ligand exchange and/or dissociation occurs, as concluded from spectral absorptions in combination with conductivity measurements.
The variation of the activity coefficients of cations with the hydrogen ion concentration in aqueous perchloric acid‐sodium perchlorate and perchloric acid‐lithium perchlorate mixtures of constant ionic strength
Authors: Gelsema W. J. , de Ligny C. L. , Remijnse A. G.
Published: September 2010

The variation of the activity coefficient of some cations and of the ratio of the activity coefficients of the ions of some redox systems with the hydrogen ion concentration has been measured at several (constant) values of ionic strength in perchloric acid‐sodium perchlorate and perchloric acid‐lithium perchlorate mixtures at 25°.

These variations differ considerably among different cations or redox systems. They are about the same in perchloric acid‐sodium perchlorate and perchloric acid‐lithium perchlorate mixtures of low ionic strengths but they are much larger in perchloric acid‐sodium perchlorate than in perchloric acid‐lithium perchlorate mixtures at ionic strengths > 3 mole · 1−1.
Temperature dependence of the Raman spectrum of NOSbCl6
Authors: Stufkens D. J. , Gerding H.
Published: September 2010

Attention is paid to the tentative preparation of NOSbCl4, the only product being NOSbCl6.

The temperature dependence in the Raman spectrum of NOSbCl6 is explained in terms of the coupling between NO+ and SbCl6−.
Réactions D'amines Germaniées avec les Aldéhydes et les Cétones
Authors: Riviere‐Baudet M. , Satgé J.
Published: September 2010

The insertion of aldehydes and ketones onto the germanium‐nitrogen bond of trialkylgermylamines leads to α‐aminoalkoxygermanes which are generally not very stable.

Their decomposition leads to trialkylgermanium oxides and enamines or imines corresponding to the aminogermanes and carbonyl derivatives.

The formation of enamine or imine takes place through gem‐diamines which are usually unstable. The derivatives obtained by insertion of the halogenated aldehydes and ketones such as chloral and hexachloroacetone decompose through β‐elimination, with formation of trialkyl(trichloromethyl)germane R3GeCCl3, trialkylchlorogermane and dichlorocarbene.
Trans‐substitution and equilibration of phenols: Part II. Trans‐t‐butylation of phenols in the presence of para‐toluenesulfonic acid as the catalyst
Authors: Willemse F.R.J. , Wolters J. , Kooyman E.C.
Published: September 2010

Phenols containing a free ortho position can be alkylated by ortho‐t‐butyl‐phenols in the presence of catalytic amounts of p‐toluenesulfonic acid at temperatures between ∼ 60 and 100°.

Using, e.g., 2,6‐di‐t‐butyl‐p‐cresol as an alkylating agent, trans‐t‐butylations were carried out with a number of para‐ and ortho‐substituted phenols.

The above mentioned reactions lead to equilibria of the type: 2,6‐di‐t‐butyl‐p‐ZC6H2OH + p‐ZC6H4OH ⇄ 2 (2‐t‐butyl‐p‐ZC6H3OH)

The equilibrium constant (K = 43 at 80°C) is independent of the substituent present in the phenolic nucleus.

For Z = p‐CH3 the energy of activation of the forward reaction amounts to 18.5 kcal/mole. Ortho‐para isomerization occurs, when the 3, 4 and 5 positions are free. Several differences between the catalytic effects of p‐toluenesulfonic acid and aluminium phenoxide are discussed.
Theoretical calculation of retention indices of apolar solutes on apolar stationary phases and a discussion of their temperature coefficients and of the corresponding standard partial molar entropies, enthalpies and free enthalpies of vaporization from solution
Authors: Hammers W. E. , de Ligny C. L.
Published: September 2010

A method is proposed for calculating retention indices of apolar solutes on apolar stationary phases from the vapour pressures of the solutes and the molar volumes of the solutes and the solvent. Retention indices calculated by this method, as well as values calculated otherwise, are compared with experimental data.

The temperature dependence of the retention indices is discussed from a thermodynamic standpoint.

The corresponding standard partial molar entropies, enthalpies and free enthalpies of vaporization from solution appear to depend on molecular size and shape. The latter phenomenon is contributed to more or less shielded solute‐solvent interactions and to less or more restricted molecular translation and rotation.
IR and NMR studies of symmetrically and unsymmetrically bonded N,N‐dialkyldithiocarbamates
Authors: Brinkhoff H.C. , Grotens A.M.
Published: September 2010

In order to find characteristic differences between symmetrically and unsymmetrically bonded N,N‐dialkyldithiocarbamates, their IR and 1H NMR spectra have been examined. The IR data firmly underline a previously reported infrared criterion which makes it possible to distinguish the two types of bonding. In the spectra of the unsymmetrical N,N‐diethyldithiocarbamates a band at 1000 cm−1 is assigned to the CS stretching mode.

Although the rotation around the S2C‐NR2, bond in several dithiocarbamato complexes will be strongly hindered at low temperatures, no splitting of the NMR signals of the N‐alkyl groups could be observed. This may be attributed to an extremely small difference in magnetic environment of the N‐alkyl moieties in the rotamers.