bluuebunny/crossref_metadata_2025 huggingface dataset:
An analysis of the thermodynamics of transfer of polar non-electrolytes from water to aqueous concentrated salt solutions
Authors: Cross RF , McTigue PT
Published: September 2010

A calorimeter has been
constructed and used to determine the limiting enthalpies of solution (ΔHS)
of a series of alkyl acetates (methyl, ethyl, propyl, butyl and t-butyl) in
water and aqueous solutions of some of the following salts: LiCl,
NaCl, KCl, CsCl, KF, KBr, NaNO3
and NaClO4. These measurements are combined with previous activity
coefficient determinations to obtain the thermodynamics of transfer for the
esters. In the case of transfer to NaCl solutions,
scaled-particle theory calculations are used to determine the thermodynamics of
cavity transfer, which, when combined with the experimental total-transfer
quantities, give rise to a set of quantities that we have called the
interaction transfer quantities. These quantities indicate that the predominant
factors in the transfer of neutral molecules containing both polar and
non-polar segments from water to NaCl solutions are
the transfer of the cavity and of the interactions of the polar group. The
interactions of the alkyl side chains are shown to be similar to those of
alkane molecules.
Crystal structure and E.S.R. of 2,2'-Bipyridylium Tris(2,2'-bipyridyl)iron(III) tetraperchlorate
Authors: Figgis BN , Skelton BW , White AH
Published: September 2010

The crystal structure of
the title compound (C10H9N2) [Fe(C10H8N2)3]
(ClO4)4 has been determined at c. 295 K from
diffractometer data and refined by least squares to R 0.056 (7018 reflections
with I > 3σ(I)). Crystals are triclinic, Pī,
a 16.607(3), b 13.496(3), c 10.254(2) Ǻ, α 101.13(2), β
92.08(2), γ 102.77(1)°, Z 2. The iron atom is surrounded by three
bidentate ligands, the six Fe-N distances being equal ( 1.963
Ǻ). The monoprotonated bipyridylium cation adopts the unusual cis
configuration, with the proton clearly located on one of the nitrogen atoms.
The e.s.r. g-tensor is approximately axial (g|| 1.474, g,
2.690) but its axes do not coincide with obvious geometric features
of the cation.
Electrochemical synthesis of amino acids by reductive amination of keto acids. II. Reduction at platinum black and palladium black electrodes
Authors: Jeffery EA , Johansen O , Meisters A
Published: September 2010

2-Amino-2-phenylacetic
acid, monoammonium glutamate, 2-aminobutyric acid, α-alanine and ammonium
5-amino-5-phenylvalerate have been prepared by electrochemical reductive
amination of the corresponding keto acids (or their sodium salts) in aqueous
ammonia. Platinum black, platinum black/Teflon composite on tantalum gauze and
palladium black were used as electrodes. The yields ranged from 40% for α-alanine
and ammonium 5-amino-5-phenylvalerate to 83% for 2-amino-2-phenylacetic acid,
at ammonia concentrations from 4.7 to 15.5 M. The corresponding reduction
potentials were all between -0.82 and -0.90 V relative to a saturated calomel
electrode. Decreasing the ammonia concentration decreased both the yield and
the current efficiency for reductive amination of 2-oxo-2-phenylacetic acid. ��� 2,5-Diphenylimidazol-4-ol was prepared and
isolated from a concentrated solution of 2-oxo-2-phenylacetic acid in strong
ammonia. Small amounts of this compound probably cause the yellow coloration
observed during electrolysis of 2-oxo-2-phenylacetic acid.
Colouring matters of Australian plants. XX. Synthesis of hydroxyanigorufone and related phenalenones
Authors: Cooke RG , Dagley IJ
Published: September 2010

The structure of
hydroxyanigorufone, one of the pigments of Anigozanthos rufus Labill., has been
confirmed as 2-hydroxy-9-(4-hydroxyphenyl)phenalenone by synthesis. The
general application of two synthetic methods, 9-arylation through addition of
Grignard reagents and 2-hydroxylation through epoxidation, is demonstrated by
the preparation of several other phenalenones related to natural products.
The chemistry of pyrrolic compounds. XXXIX. Dihydro and monohydrated derivatives of protoporphyrin IX
Authors: Clezy PS , Fookes CJR , Hai TT
Published: September 2010

Rational syntheses of the dihydro [(1d), (1e)] and monohydrated [(1b), (1c)]
derivatives of protoporphyrin IX dimethyl ester have been completed. It has
also been shown that the latter isomers [(1b), (1c)] can be obtained either
from haematoporphyrin IX dimethyl ester (1a) by partial dehydration, or from
diacetyldeuteroporphyrin IX dimethyl ester (1f) by partial reduction followed
by dehydration and reduction.
Pyridazine-3,4,6-trithiol and some N- and S-methyl derivatives
Authors: Barlin GB , Lakshminarayana P
Published: September 2010

Pyridazine-3,4,6-trithiol
has been prepared and its pKa values and U.V. spectra compared with
those of some N- and S-methyl derivatives. It is evident that the compound does
not exist as the trithiol or as the 1H tautomeric form.
Electron spin relaxation in solutions of transition metal ions with S ≥ 1. Conditions where the Redfield limit is valid
Authors: Gregson AK , Doddrell DM , Pegg DT
Published: September 2010

Electron spin relaxation
for S = 2 by modulation of the quadratic zero- field splitting under conditions
when Te2 > Tl, is treated theoretically. It
is shown that the appropriate relaxation matrices when solved numerically yield
at high-field strengths two different electron spin relaxation times with different
relative weightings. The relative weights are field-dependent, there being only
one longitudinal and one transverse relaxation time at low-field strengths. The
relaxation matrices for S = 1, 3/2,2,5/2 are summarized in the Appendix.
Organomercury compounds. XXIII. Organomercuric Quinolin-8-olates
Authors: Bertino RJ , Deacon GB , Miller JM
Published: September 2010

The complexes RHg(ox) (R = C6F5, p-HC6F4,
or p-MeOC6F4; ox = quinolin-8- olate)
have been prepared by reaction of thallous quinofin-8-olate with the
appropriate organomercuric chlorides whilst PhHg(ox
or meox), MeHg(ox),H2O,
and MeHg(meox) (meox = 2-methylquinolin-8-olate) have been obtained from
phenyl- or methyl-mercuric hydroxide and quinolin-8-ol or
2-methyl-quinolin-8-ol. Although MeHg(ox),H2O
was readily dehydrated, the water could not be displaced by ligands (e.g. Ph3PO,
Me2SO). Chelation of the quinolin-8-olate ligands (rather than
unidentate O- bonding) was established for all complexes by ultraviolet/visible
spectroscopy. Molecular weight data indicated that all complexes except MeHg(ox) and MeHg(ox),H2O
are partly associated in benzene, chloroform and/or carbon tetrachloride [K(2 monomer
↔ dimer) in the range 1-40 mol-1 dm3]; this
suggests an associated structure in the solid state. Some supporting evidence
for associated structures was obtained by mass spectrometry. The structural
conclusions are discussed in the light of crystal structures of PhHg(ox) and PhHg(meox) carried out in a concurrent investigation.
The chemistry of pyrrolic compounds. XL. A new synthesis of protoporphyrins III and XIII and a 1H N.M.R. study of the preferred pathway of electron delocalization in the porphyrin macrocycle
Authors: Clezy PS , Fookes CJR , Sternhell S
Published: September 2010

The synthesis of
protoporphyrins III and XIII as the dimethyl esters has been completed by an
oxidative cyclization of biladiene-ac intermediates. Protoporphyrin III has
been converted into deuteroporphyrin III and measurements of the proton
coupling constant in the allylic unit, CH3-C=C-H, of this latter
porphyrin point to the double bond of this system having a significantly
diminished bond order. This finding is in accord with the view that the π-electron
delocalization pathway in the porphyrin macrocycle involves the periphery of
the molecule.
Complexes containing unsaturated medium rings: The crystal and molecular structures of two rhodium(I) complexes
Authors: Mason R , Scollary GR
Published: September 2010

The crystal and molecular
structures of two rhodium(I) complexes with long-chain alkyne- or alkene-α,ω-diyldiphosphines have been determined by
single-crystal X-ray diffraction techniques. RhCl(CO){But2P(CH2)4C≡C(CH2)4PBut2}
crystallizes in the orthorhombic space group Pna21 with a 21.991
(2), b 11.915(1), c 11.890(1) Ǻ and Z 4. The structure was refined by
least-squares methods to a conventional R factor of 0.097 for 1768 independent
reflections (Mo Kα diffraction data). The
rhodium ion is in a square-planar coordination geometry with trans-phosphorus
atoms; the unsaturated (alkynyl) group is not bonded to the rhodium. Crystals
of RhCl{But2P(CH2)2CH=CH(CH2)2-
PBut2} are monoclinic, space group P21/c, a
20.783(12), b 8.580(4), c 14.799(9) Ǻ, β 100.70(2)°, Z 4. The
structure analysis has converged to R 0.069 for 1417 reflections (Mo Kα diffractometry); the coordination geometry of the
rhodium is again planar with the ethylenic group occupying a single bonding
site. The effect of ring size on the rhodium-phosphorus bond lengths is
discussed.
The 9-decalyl and related cations. V. Generation of cis- and trans-2-t-Butyl-9-decalyl cations through π-routes by acetolysis
Authors: Gream GE , Serelis AK
Published: September 2010

The synthesis and
solvolytic behaviour (in buffered acetic acid) of 4-
(5?-t-butylcyclohex-1'-enyl)but-1-yl p-nitrobenzenesulfonate (6) and 3-
(cyclohex-1'-enylmethyl)-4,4-dimethylpentyl p-nitrobenzene-sulfonate (7) are
described. Kinetic and product studies have shown that π-bond
participation occurs in the acetolysis of both compounds. The rate
enhancements, compared with saturated analogues, are c. 46 and 8290 for (6) and
(7). The considerably greater rate enhancement observed for (7) is a
manifestation of the 'gem-dialkyl' effect and is explained in terms of the
effect of the t-butyl group on the conformations that the side chain might
adopt. ��� The acetolyses of (6) and (7) give rise to
cyclized products (c. 97 and 100%) arising from both cis- and trans-2-t-butyl-9-decalyl
cations (2) and (3). The compositions of the products, which also include
compounds formed from the cis-cation (55) obtained by a 1,2-hydride shift in
(2), show that (6) and (7) do not react via the same cationic species. ��� Ion-pairs of an undefined nature are
implicated in the reactions. Entirely consistent evidence was not obtained for
the hypothesis that the counter-ion, behaving as a base, probably plays a
significant role in olefin formation from the cis- and trans-cations (2) and
(3) in ion- pairs that might be formed initially from (6) and (7).
Crystal structure of 7-t-Butyl-3-(5'-t-butyl-3'-methylfuran-2'-yl)-5-methylbenzofuran-2(3H)-one
Authors: Hall SR , Raston CL , Skelton BW , White AH
Published: September 2010

The crystal structure of
7-t-butyl-3-(5'-t-butyl-3'-methylfuran-2'-yl)- 5-methylbenzofuran-2(3H)-one, C22H28O3,
has been determined at 295 K from diffractometer data and refined by least
squares to a residual of 0.062 for 1830 'observed' reflections. Crystals are
triclinic, Pī, a 11.210(3), b 9.742(3), c
9.389(4) Ǻ, α 88.02(3), β 85.32(3), γ 77.13(2)°, Z 2.
Grand ensemble Monte Carlo study of crystallization in sub-monolayer adsorption at a solid vapour interface
Authors: Lane JE , Spurling TH
Published: September 2010

A grand ensemble Monte
Carlo procedure is used to examine the thermodynamic properties of a
crystal-like layer of krypton adsorbed at sub-monolayer coverages on graphite
at 90.12 K. The effect of the periodic boundary conditions on these properties
is discussed and used to develop a thermodynamically consistent iterative
procedure to estimate the transition pressure and thereby fix the adsorption
isotherm.
Solvolytic reactions of Lewis acids in dichloroacetic acid and the nature of the solvolysed products
Authors: Malhotra KC , Mehrotra G , Mahajan VP , Chaudhry SC
Published: September 2010

Tetrachlorides of tin,
titanium, zirconium, thorium and silicon form compounds of composition SnCl2(CHCl2COO)2,
Ti(CHCl2COO)4, Zr(CHCl2COO)4,
Th(CHCl2COO)4 and Si2O(CHCl2COO)6
when refluxed with excess of dichloroacetic acid. From i.r.,
molecular weight and conductance studies, their structures have been
elucidated. Their Lewis acid character is established by isolating and
characterizing their adducts with organic tertiary bases. Antimony
pentachloride, aluminium trichloride and iron(III) trichloride form compounds
of composition SbCl2(CHCl2COO)3, Al(CHCl2COO)3
and FeCl(CHCl2COO)2 when
refluxed with excess of the solvent and these have been characterized by i.r.
studies.
Carbon-13 N.M.R. studies of carbocations. II. An investigation of the correlation between carbon chemical shifts and σ+ constants for 1-phenylethyl cations
Authors: Kelly DP , Spear RJ
Published: September 2010

Eighteen
1-methyl-1-phenylethyl (cumyl) (1) and 1-phenylethyl
(styryl) (2) carbocations have been prepared in known concentration in FSO3H/SbF5
solution from their corresponding carbinols and their 1H and 13C
spectra have been measured. The correlations of both the methyl 1H
shifts [δH(Me)] and methyl 13C shifts
[δC(Me)] with the cationic carbon shifts [δ(C+)]
have been determined. In the case of δC(Me)
curves are obtained indicating non-linearity of chemical shifts with charge
density. Correlations of δ(C+) with Brown's σ+ constants are only
fair, the deviation from linearity being interpreted in terms of non-linear
dependence of either δ(C+) or σ+, or both, on charge density at this
level of charge. The use of an enhanced substituent constant (σ++) and/or
the dual substituent parameter equation improves the correlation. Non-linearity
in the plot of δ(C 1) against σ+ reported for
2-arylnorborn-5-en-2-yl(4) and 2-arylnorbornan-2-yl cations (5) has been shown
to occur also in the case of δC(Me) of the cumyl cations (1). The implications of this finding with
respect to the structures of (4) and (5) are discussed.
A study of methyl-substituted 2-Arylbicyclo[2,2,1]hept-2-yl cations
Authors: Coxon JM , Steel PJ , Coddington JM , Rae ID , Jones AJ
Published: September 2010

The 13C and 1H
N.M.R. spectra of a series of 2-aryl-1,7,7- trimethylbicyclo[2,2,1]hept-2-yl
cations generated in strong acid at low temperature are reported. These cations
reorganize at higher temperatures to 2-aryl-5,5,endo-6-trimethylbicyclo[2,2,1]hept-2-yl
cations, thereby relieving the unfavourable C 1 methyl-C 2 aryl steric
interaction present in the parent cations. At higher temperatures the bicyclic
skeletons collapse to monocyclic allylic cations.
The Structure and Synthesis of Cytokinin Metabolites. II. Lupinic Acid and O-β-D-Glucopyranosylzeatin From Lupinus angustifolius
Authors: Duke C , Macleod J , Summons R , Letham D , Parker C
Published: September 2010

Two new metabolites of
exogeneously supplied zeatin have been identified in de-rooted lupin seedlings
as L-lupinic acid (2) and O-β- D-glucopyranosylzeatin
(3). Their structures have been confirmed by syntheses which provide new and
general methods for the preparation of these types of compounds.
Nucleophilic alkenes. III. Addition of 1,1-dialkoxyethenes to 1,4-naphthoquinones. The 1 : 2-process
Authors: Cameron DW , Crossley MJ , Feutrill GI , Griffiths PG
Published: September 2010

Anthraquinones have been
synthesized by 1 : 2-addition of 1,1- dialkoxyethenes to 1,4-naphtho-quinones,
prior bromination of the naphthoquinone being unnecessary. The reactions were
markedly accelerated by polar solvents and there was orientational specificity
in most cases. Addition to 5-hydroxy-1,4-naphthoquinones gave derivatives of
1,3,8-trihydroxyanthraquinone while 5-methoxy-1,4- naphthoquinone gave the
1,3,5-substitution pattern. 6-Hydroxy- and 6- alkoxy-naphthoquinones
gave chiefly the 1,3,7-orientation, appropriate prior bromination being
required to generate the 1,3,6-series. These orientations are interpreted in
terms of initial nucleophilic attack of 1,1-dialkoxy-ethene at a quinonoid
carbon. This also takes into account concurrent 1 : 1-addition processes.
Chemistry of the Coccoidea. V. Synthesis of 2-acetylemodin and of deoxyerythrolaccin
Authors: Cameron DW , Crossley MJ , Feutrill GI , Griffiths PG
Published: September 2010

The anthraquinones
2-acetylemodin and deoxyerythrolaccin have been synthesized, the former for the
first time, by processes involving addition of 1,1-diethoxyethene to
appropriately substituted naphthoquinones. These coccid pigments are based on
polyketide systems incorporating respectively the 1,3,8- and
1,3,6-trihydroxyanthraquinone skeletons.
Direct formation of 3,3,6,6-Tetraaryl-1,2-dioxans from 1,1-Diarylethylenes and oxygen, catalysed by antimony(V) chloride
Authors: Haynes RK , Probert MKS , Wilmot ID
Published: September 2010

1,1-Diphenylethylene,
1,1-di-p-tolylethylene, 1,1-di-p-anisylethylene and 1,1-di(p-t-butylphenyl)-ethylene are converted in high yields (80- 90%)
into the corresponding 3,3,6,6-tetraaryl-1,2-dioxans in the presence of oxygen
and catalytic amounts of antimony(v) chloride in dichloromethane at -40° to
-78° under irradiation from a tungsten lamp.
Diterpene chemistry. VII. Sulfur-containing derivatives of Labda-8(17),14-dien-13-ol (Manool)
Authors: Grant PK , Liau HTL
Published: September 2010

The reactions of manool
derivatives with sulfurated sodium borohydride to give sulfur-containing
diterpene derivatives are reported. 13,17-Epithio-8,13-epoxy-14,15-dinorlabdane
(12), the sulfur analogue of the highly odiferous compound 8,13:13,17-diepoxy-14,15
dinorlabdane (4), has been synthesized. A simple but very effective use of
silver nitrate to prevent double-bond participation in an acetalization
reaction is reported.
Some amino-substituted derivatives of L-mimosine
Authors: Stewart FHC
Published: September 2010

Several amino-substituted
derivatives of the chemical defleecing agent L-mimosine have been synthesized,
including the peptide glycyl-L- mimosine. Preparative difficulties associated
with the charge distribution in this basic amino acid are noted.
Equilibria in complexes of N-heterocyclic molecules. XVII. Covalent hydration and the rate of dissociation of the Bis(2,2':6',2'-terpyridyl)iron(III) ion in acid solution
Authors: Walters WS , Gillard RD , Williams PA
Published: September 2010

The dissociation of Fe(tpy)23+ has been studied in aqueous
sulfuric acid. The rate of reaction increases upon addition of small amounts of
acid, reaches a maximum, and then falls to zero in a complex fashion as the
acid approaches limiting concentration, and aH2O falls to zero. No
dissociation occurs in the absence of water, and it is evident that covalent
hydration of the complex is an essential step in the dissociation process.
The low-frequency vibrational spectra of the 1 : 1 acridine-bromine and 2 : 3 acridine-iodine complexes
Authors: Bowmaker GAKRJ
Published: September 2010

The low-wavenumber
(<400 cm-1) vibrational spectra of the 1 : 1 acridine-bromine
complex, the 2 : 3 acridine-iodine complex, and tetrabutylammonium pentaiodide
have been measured, and these indicate that the bromine complex is the
molecular compound acridine-dibromine (1/1) and the iodine complex is the ionic
compound bis(acridine)iodine(I) pentaiodide. An attempted preparation of
bis(acridine)iodine(I) nitrate was unsuccessful, the iodine(I) being reduced to
molecular diiodine.
The Constituents of Rubus rosifolius. The Structure of Rosifoliol, a Biogenetically Significant Sesquiterpenoid
Authors: Southwell I
Published: September 2010

Chemical investigation of
the steam-volatile oil of the shrub Rubus rosifolius yielded pregeijerene
(2), β-caryophyllene (3), humulene (4),
dihydroagarofuran (5), an unidentified sesquiterpene ether, hedycaryol (6) and
the novel epieudesmol rosifoliol for which structure (1) is proposed. The bio-
genetic significance of these constituents and the carbon-13 magnetic resonance
spectra of rosifoliol and related compounds are discussed.
Copolymerization of 2,3:4,5-Di-O-isopropylidene-1-vinylbenzyl-β-D-fructopyranose with styrene: Preparation of polymers containing carbohydrate side chain residues and effect of composition on glass transition temperatures
Authors: Busfield WK , Franke FP , Guthrie RD
Published: September 2010

A range of copolymers of
styrene and 2,3:4,5-di-O-isopropylidene-1- vinylbenzyl-β-D-fructopyranose
(A) were prepared by free-radical initiation and characterized by i.r., N.M.R., microanalysis and solution viscosity.
Reactivity ratios were derived. The specific rotation of the copolymers was
linearly related to the molar composition. The glass transition temperatures of
the copolymers decreased almost linearly with decreasing styrene content to a
value of 73°C for the homopolymer of monomer (A). A method of releasing the
isopropylidene blocking groups was developed; the glass transition temperatures
of the resultant fructopyranose copolymers increased with decreasing styrene
content to a value of 132°C for a copolymer containing 45 mole % styrene.
A study of cations generated from 1-Methyl- and 7,7-Dimethyl-2-phenylbicyclo-[2,2,1]heptan-2-ols
Authors: Brown RFC , Coddington JM , Coxon JM , Jones AJ , Rae ID , Steel PJ
Published: September 2010

Attempts to generate the
1-methyl-2-phenylbicyclo[2,2,1]hept-2-yl cation (6) by reaction of
1-methyl-exo-2-phenylbicyclo[2,2,1]heptan- endo-2-ol
(5) with HSO3F in SO2ClF were not successful, due to
spontaneous rearrangement to endo-6-methyl-2-phenylbicyclo[2,2,1]hept- 2-yl cation (7). This cation (7) itself rearranges at
higher temperatures to exo-6-methyl-2-phenylbicyclo[2,2,1]hept-2-yl cation (10)
probably by a double Wagner-Meerwein rearrangement involving the intermediacy
of 3-methyl-1-phenylbicyclo[3,1,1]hept-2-yl cation (11). The 7,7-dimethyl-2-phenylbicyclo[2,2,1]hept 2-yl cation (13) has been generated and shown to
rearrange to 5,5-dimethyl-2- phenylbicyclo[2,2,1]-hept-2-yl
cation (14). At higher temperature, the bicyclic skeleton collapses to 3-isopropyl-1-phenyl-cyclohex-2-en-1-yl
cation (15). These results demonstrate the structural requirements for cleavage
of the 1,7-bond in the bicyclo[2,2,1]heptane skeleton.
Synthetic Applications of Intramolecular Insertion in Arylcarbenes. II. o-Alkoxy-, Dialkylamino- and Alkylthio-phenylcarbenes
Authors: Crow WD , McNab H
Published: September 2010

A series of phenylcarbenes,
substituted in the ortho-position by alkoxy, dialkylamino and alkylthio side
chains containing up to three carbon atoms, has been generated in the gas phase
and pyrolysed at 250-750�/0.05-0.20mm. Carbene insertion occurs in moderate to
high yield to give the appropriate five-and six-membered heterocyclics, the
former predominating. The regioselectivity of the carbene insertion
(five-membered ring us six-membered ring) is highest in the case of the alkoxy
and dialkylamino compounds, where six-membered-ring formation is relatively
minor; in the case of the alkylthiophenylcarbenes, the selectivity in favour of
the smaller ring is, by comparison, small. The reasons for this are discussed
in terms of the geometry of the transition state and the donor capacity of the
heteroatom.
Vinylindenes and Some Heteroanalogues in the Diels-Alder Reaction, VII. Vinylbenzo[b]thiophens and 1,4-Naphthoquinone
Authors: Cherry WH , Porter QN
Published: September 2010

A mechanism postulated for
the base-catalysed oxidative rearrangement of 5,5a,6,12a,12b,13-hexa-hydroanthra[l,2-b]benzo[d]thiophen-5,13-dione (the adduct
of 3-vinylbenzo[b]thiophen and 1,4-naph-thoquinone) to anthra[2,3-b]benzo[d]thiophen-7,12-quinone is supported by isolation of a 5a,6-di-hydro
derivative when the reaction is carried out in the absence of oxygen. Similar
derivatives are formed from two methyl homologues of the adduct. Conditions are
described for conversion of the adducts into 6,7-dihydroanthra[l,2-b]benzo[d]thiophen-5,13-quinones, and it is also shown that
2-methyl-3-vinylbenzo[b]thiophen and
1,4-naphthoquinone give an adduct in which the diene has undergone
isomerization before adduct formation.
N-Aminopyrimidines: The Isomerization of 1-Aminobarbituric Acids to 2-(5-Oxo-4,5-dihydro-1H-1,2,4-triazol-3-yl) Aliphatic Acids
Authors: Jacobsen NW , McCarthy BL , Smith S
Published: September 2010

1-Aminobarbituric acid
undergoes a facile isomerization in aqueous acid to 2-(5-oxo-4,5-dihydro-lH-l,2,4-triazol-3-yl)acetic acid which
in turn can be decarboxylated to give 3-methyl-1H-1,2,4- triazol-5(4H)-one. The isomerization reaction is shown to be a general one,
adaptable to the synthesis of oxotriazolyl aliphatic
acids and their decarboxylated products. A reaction
mechanism for the isomerization is proposed.
Acid-Catalysed Dimerization of exo-2-Arylbicyclo[2,2,1]heptan-endo-2-ols
Authors: Coxon JM , Robinson WT , Steel PJ
Published: September 2010

This paper discusses the
reactions of exo-2-arylbicyclo[2,2,1]heptan-endo-2-ols with concentrated perchloric acid which afford the dimers (1RS,2SR,4SR,2'RS,4'SR,7'SR,8'RS)-7'-(aryl)spiro[bicyclo-[2,2,l]heptane-2,9'-tetracyclo[8,4,0,02,7,04,8]tetradeca-10',12,14'-triene]
and (1RS,2SR,4SR,1'SR,- 2'RS,10'RS,11'RS)-2-(aryl)spiro[bicyclo[2,2,1]heptane-2,9'
tetracyclo[9,2,1,02,10,03,8]tetradeca- 3'5',7'-triene]. The crystal structure of (1RS,2SR,4SA,1'SR,2'RS,10'RS,11'RS)-5'-chloro-2'-(4~'-chlorophenyl)spiro[bicyclo[2,2,1]heptane-2,9'-tetracyclo[9,2,1,02,10,03,8]tetradeca-3',5',7'-triene],
determined from X-ray diffraction data and refined by least-squares to a
residual of R 0.137 (3715 observed reflections), is reported. The crystals are
monoclinic, P21/c, with two molecules in the asymmetric unit; a 10.062(1), b 19.004(2), c 21.539(2)�
β 96.42(1)�, Z 8.
A Molecular Orbital Study of the Stereochemistry of Pentacoordinated Aluminium
Authors: Hill RJ , Gibbs GV , Peterson RC
Published: September 2010

An attempt has been made to characterize the stereochemical requirements of an aluminium atom
coordinated by five hydroxyl groups (AlO5H52-) within the framework of CNDO/2 molecular orbital
formalism. Total energy surfaces calculated for this system as the valence angles are varied within
the constraints of C2v symmetry clearly show the 'reaction coordinate' for the so-called Berry pseudo-
rotation mechanism. With all Al-O and O-H bond lengths fixed at 1.84 and 1.00 Ǻ respectively,
the activation energy for trigonal-bipyramidal/square-pyramidal interconversion is 7.1 kJ mol-1. In
addition, the minimum energy O(axial)-Al-O(basal) angle for the square-pyramidal group is estimated
to be c. 103.5°. When one bond is lengthened relative to the other four the trigonal-bipyramidal
configuration is further stabilized, but approaches tetrahedral geometry. When one bond is shortened
square-pyramidal geometry is stabilized and the minimum energy O(ax)-Al-O(bs) angle increases.
With two bonds lengthened (or shortened) the favoured trigonal-bipyramidal configuration is the
one with long bonds directed towards the axial positions and at no stage is there a stabilization of
square-pyramidal geometry. These results agree with trends in calculated Mulliken bond overlap
populations and with observed ratios of axial-to-basal bond lengths in suggesting that for trigonal-
bipyramidal stereochemistry the axial bonds are weaker, whereas for square-pyramidal geometry
the axial bond is stronger. Moreover, consideration of the total energy for various isomers of
Al(OH)4F2- indicates that more electronegative substituents prefer to enter the apical and basal
positions in a trigonal bipyramid and a square pyramld respectively. For a cluster Al2(OH)82-,
consisting of two aluminium trigonal-bipyramidal groups sharing a common edge of variable length,
an energy minimum (62.2 kJ mol-1 lower than the undistorted case) is found at a shared edge length
of 2.246 A, 13 % shorter than for the undistorted polyhedron. The corresponding observed distance
for a similar dimer in the mineral andalusite, Al2SiO5, is 2.247(7) Ǻ. Plots of minimum energy
shared edge length against mean bond length for various clusters M2(OH)8n-, where M = Al or Mg,
clearly demonstrate an essentially linear relationship between the two parameters consistent wlth
trends observed for natural systems in which M = Co, Cu, Mn and Zn.
Crystal Structure of Calcium Picrate Pentahydrate: A New Eight-Coordinate Stereochemistry for [M(bidentate)2(unidentate)4]
Authors: Diakiw V , Hambley TW , Kepert DL , Raston CL , White AH
Published: September 2010

The crystal structure of
the title compound, Ca(C6H2N307)2,5H2O,
has been determined by single-crystal X-ray diffraction at 295(1) K and refined
by least squares to a residual of 0.049 for 1513 'observed' reflections.
Crystals are orthorhombic, Pmab, a 24.169(6), b l0.292(7), c 8.554(2) �, Z 4. The stereochemistry about the calcium has not
been observed previously for the system [M(bidentate)2- (unidentate)4]; in the present structure, the
calcium is coordinated by a pair of bidentate picrate
ligands and the four water molecules in an array in which three of the water
molecules occupy a triangular face of a square antiprism,
the overall array having m symmetry.
The remaining water molecule occupies a lattice site with no close interaction
with the other species.
Mechanisms for the Benzoylation of 2-Aminopyridine
Authors: Deady LW , Stillman DC
Published: September 2010

Relative rate studies on
ring methyl-substituted derivatives of 2-aminopyridine in pyridine solvent show
that reaction with benzoyl chloride gives monobenzoyl derivatives by direct
reaction on the exocyclic nitrogen (N'). The reaction is analogous to acetylation
with acetic anhydride. Reaction in acetone, however, gives, except for the
6-methyl compound, N',N?-dibenzoylamino
compounds, even in the presence of excess of amine. The results are shown to be
consistent with ring nitrogen benzoylation (N1), followed by rapid
N'-benzoylation and intramolecular benzoyl rearrangement from N1 to N'.
Lanthanide Shifts in the 1H N.M.R. Spectra of 1,4-Naphthoquinones
Authors: Cameron DW , Feutrill GI , Patti AF
Published: September 2010

Lanthanide-induced shifts
are discussed for 38 naphthoquinones incorporating a wide variety of substituents.
For substrates unsymmetrically substituted in the
benzenoid ring the shift reagent leads to spectroscopic differentiation of the quinonoid protons H2 and H3 in most cases. This has
permitted assignment of substituents to one or other of these positions, an
approach exemplified forderivatives of 5- and
6(7)-methoxy-1,4-naphthoquinone.
Carbon-13 N.M.R. Studies of 1,4-Naphthoquinones and 9,10-Anthraquinones
Authors: Bowden BF , Cameron DW , Crossley MJ , Feutrill GI , Griffiths PG , Kelly DP
Published: September 2010

Carbon-13 n.m.r,
spectra of a range of hydroxy-, methyl-, methoxy- and halo-substituted
1,4-naphthoquinones and methyl-substituted 9,10-anthraquinones have been
measured and assignments made on the basis of 13C-1H and 13C-19F
coupling constants, selective proton-decoupling and deuterium-labelling
experiments. The quinonoid carbon (C2 and C3)
resonances in juglone (4) and juglone
methyl ether (7) have been assigned unequivocally from the spectra of deuterated
derivatives. Substituent effects are discussed in comparison with previously
published data.
A New Series of Diterpenes from Australian Spongia Species
Authors: Kazlauskas R , Murphy PT , Wells RJ , Noack K , Oberhansli WE , Schonholzer P
Published: September 2010

Great Barrier Reef sponges
of the genus Spongia have yielded
eight closely related tetracyclic furanoditerpenes. The structures, assigned on
the basis of spectral methods, have been confirmed by a single-crystal X-ray
analysis of one of the metabolites and the relative stereochemical features
have been defined. The absolute configuration of this metabolite was determined
by circular dichroism, which allowed the relationship between the eight new
compounds to be determined.
Cyclopentadienyl-ruthenium and-Osmium Chemistry. IX. Some Substituted η1-Vinylidene and η1-Acetylide Complexes
Authors: Bruce MI , Wallis RC
Published: September 2010

Reactions between RUCI(PPh3)2(η-C5H5),
RuCI(L2)(η-C5H5)(L2
= dppm or dppe) or OsBr(PPh3)2-(η-C5H5)
and the alk-1-ynes HC2R (R = Me, Pr, CO2Me, Ph, C6H4F-p or C6F5), in the
presence of NH4PF6, NH4BF4 or NaBPh4,
have given the corresponding cationic η1-vinylidene
complexes [Ru(C=CHR)(PPh3)2(η-C5H5)]+,[Ru(C=CHPh)(L2)(η-C5H5)]+
or [Os(C=CHP~)(PPh3)2(η-C5H5)]+.
These cations are readily deprotonated to give the corresponding η1-ethynyl derivatives
Ru(C2R)-(PPh3)2(η-C5H5),
Ru(C2Ph)(L2)(η-C5H5) or OS(C2Ph)(PPh3)2(η-C5H5).
Addition of HPF6 or [R'3O]PF6 (R' = Me or Et)
to the latter affords the vinylidene complexes containing C=CHR and C=CRR'
ligands (R = Me, Pr, CO2Me, Ph, C6H4F-p or C6F5; R' = Me
or Et), respectively. The vinylidene complexes are characterized by ν(CC) bands at c. 1650 cm-1 and the metal-bonded carbon (13C)
resonance at c. 360 ppm.
Solvent Effects on the Racemization of Optically Active Tris(N-substituted carbamodithioato)cobalt (III) Complexes
Authors: Gahan LR , O'Conner MJ
Published: September 2010

The thermal racemization in
solution of some optically active tris(N-substituted
carbamodithioato)- cobalt(III) complexes [N-substituents
= diphenyl, dimethyl, diisopropyl, and tetramethylene (pyrrolidinyl)] has
been measured polarimetrically in a range of solvents including
dimethylformamide, acetonitrile, carbon tetrachloride, chlorobenzene,
chloroform, toluene and ethanol. The metal-centred (Δ ↔ Λ)
inversion reactions show first-order kinetics as expected for an intra-
molecular process. Thermodynamic activation parameters for the reaction show
that values of ΔS‡ occur over a wide range (from -124 to +60 J
K-1 mol-1) as do the values of ΔH‡ (from 67�4 to 129�3 kJ mol-1). Values for ΔG‡
are reasonably constant. Although a similar mechanism for the metal-centred
inversion is suggested for all compounds in the various solvents because of an
observed isokinetic relationship between ΔH‡ and ΔS‡, with isokinetic temperatures in the range 312-369
K, it is clear that postulates of reaction mechanisms based on the value of ΔS‡
determined in only one solvent should be treated with caution. The optically
active (-)546-tris(N,N-diisopropylcarbamodithioato)cobalt(III)
complex photoracemizes in solution without decomposition. The rate of
photoracemization is solvent-dependent being in the order bromoform � carbon
tetrachloride ≈ chloroform �benzene.
Substitution Reactions of Nitrothiophens. II. The Anomalous Reaction of 4-Nitro-2-thenylidene Diacetate with the 2-Nitropropan-2-ide Ion
Authors: Newcombe PJ , Norris RK
Published: September 2010

The reaction of
4-nitro-2-thenylidene diacetate with 2-nitropropan-2-ide ion gives rise to
4-nitro-2-thenaldehyde (6), which is converted into its Meisenheimer adduct
(13), together with small amounts of 2-(2'-methylprop-1'-enyl)-4-nitrothiophen
(a), 5-(1'-methyl-1'-nitroethyl)-2-(2-methylprop-1''-enyl)-4-nitrothiophen
(9) and 2-methyl-1-[5'-(1''-methyl-1''-nitroethyl)-4'-nitro-2'-thienyl]-2-nitro-
propyl acetate (10). Mechanistic routes relating the adduct (13), whose 1H
and 13C N.M.R. data are presented, and the two other proposed
intermediates, 5-(1'-methyl-1'-nitroethyl)-4-nitro-2-thenalde- hyde (11) and
2-methyl-2-nitro-1-(4'-nitro-2'-thienyl)propyl acetate (12), are discussed.
Nitrones and Oxaziridines. XXV. Bromination of 2-t-Butyl- and 2-Phenyl-1-pyrroline 1-Oxides
Authors: Black DSC , Blackman NA
Published: September 2010

Certain 2-t-butyl- and
2-phenyl-1-pyrroline 1-oxides undergo bromination but no 3-bromo compounds
could be observed, although their intermediacy is proposed. The isolated
products are 2H-pyrrole 1-oxide
derivatives-further brominated in some cases. 4-Bromo-3-oxo-1-pyrroline
1-oxides and 4,4-dibromo-3-oxo-1-pyrroline 1-oxides can be formed by treatment
of the related oxo nitrones with copper(II) bromide and bromine respectively.
A Proton Magnetic Resonance Study of Ligand Exchange on the Pentakis (N-formylpyrrolidine)dioxouranium (VI) Ion
Authors: Honan GJ , Lincoln SF , Williams EH
Published: September 2010

Pentakis(N-formylpyrrolidine)dioxouranium(VI)
perchlorate, [UO2(fpr)5] (ClO4)2,
has been isolated from solution. In the presence of excess free fpr the greatly
predominant species in CD2Cl2 solutions is [UO2(fpr)5]2+,
as shown by 1H N.M.R. spectroscopy, and fpr exchange is
characterized by a two term rate law:
exchange rate = 5(k1+ k2[fpr])[UO2(fpr)52+]
It is found that k1(220 K) = 42�6�0�5 s-1,
ΔH‡ = 30�7�1�4 kJ mol-1
and ΔS‡ = -71�6�6�3 J K-1 mol-1, and k2(220
K) = 369�20 dm3 mol-1 s-1, ΔH‡ = 30�5�1�0 kJ mol-1 and ΔS‡
= -54�9�5�0 J K-1 mol-1. The mechanistic implications of
these data are discussed.
Formation of ortho Diol Diacetates in the Acid-Catalysed Rearrangement of 4-Aryl-4-hydroxycyclohexa-2,5-dienones. A Structural Reassignment
Authors: Gash DM , Woodgate PD
Published: September 2010

Treatment of the p-quinols
2,6-di-t-butyl-4-hydroxy-4-phenylnaphthalen-1(4H)-one,
2,6-di-t-butyl-4-hydroxy-4-phenylcyclohexa-2,5-dienone and
2,6-di-t-butyl-4-hydroxy-4-(4'-methoxyphenyl)cyclohexa-2,5-dienone with acetic
anhydride and sulfuric acid affords, as the major product, an aromatic ortho diol diacetate.
Nitrones and Oxaziridines. XXVIII. Reaction of C-t-Butyloxaziridines with Iron(II) Sulfate : Synthesis of 3-Pyrrolin-2-ones and Other Unsaturated Pyrrolidin-2-ones
Authors: Black DSC , Blackman NA , Johnstone LM
Published: September 2010

Iron(II) sulfate converts
t-butyl oxaziridines, derived either from 5-t-butyl-2H-pyrrole 1-oxides or from 2-t-butyl-3-alkylidene- or
3-arylmethylene-1-pyrroline 1-oxides by photorearrangement, into 3-
pyrrolin-2-ones, 3-alkylidenepyrrolidin-2-ones or 3-arylmethylenepyrrolidin-2-ones
respectively.
The Interconversion of Two Elemadienolides Through Two Consecutive Cope Rearrangements
Authors: Brecknell DJ , Carman RM
Published: September 2010

Callitrin (1) at 220�
partly isomerizes to epicallitrin (9). This result, together with those of the
Cope rearrangements of some other sesquiterpenoids, is explained in terms of
the accessibility of suitable transition states and the relative stabilities of
the possible products.
Rate of Reaction of OH with HCN Between 298 and 563 K
Authors: Phillips LF
Published: September 2010

Hyroxyl resonance fluorescence was used to study the
reaction of OH with HCN in a discharge-flow system. The effect of side
reactions involving OH was assessed by numerical integration of the rate
equations for the system. The rate constant for the reaction:
OH + HCN → products
as measured at pressures
above 10 Torr and under conditions where side
reactions were believed to be unimportant, is given by the expression:
k = 1.60 ° 10-11 T-1exp(-1.86
× 103/T) cm3
molecule -1 s-1
with an estimated error of
� 20% over the temperature range from 298 to 563 K.
Volumes of Activation for the Base Hydrolysis of [Rh(NH3)5X]2+ Complex Ions
Authors: Palmer DA
Published: September 2010

The pressure dependencies
of the rates of base hydrolysis of [Rh(NH3)5X]2+
were measured at 313.2 K and μ1M, where X = Cl-,
Br-, I- and NO3-, in the range
1-1500 bar. The respective Δν‡exp
values are 19.3 � 0.9, 20.2 � 0.5, 20.4 � 0.5 and 22.3 � 0.9cm3 mol-1.
The partial molar volumes of these complexes, as well as those of other
relevant pentaamminerhodium(III) complexes, were also
determined. The volume data are discussed in terms of the conventional
dissociative conjugate base mechanism. The Δν‡exp
for the aquation of [Rh(NH3)5NO3]2+
was found to be -6.9 � 0.4cm3 mol-1 at 313.2K, [H+]
0.005M and μ0.1 M. An I
mechanism is favoured for this process.
Oxidations with lead tetraacetate. II. Oxidations of 2,2-disubstituted 1,3-benzodioxoles
Authors: Cole ER , Crank G , Minh HTH
Published: September 2010

The oxidation of
2,2-disubstituted 1,3-benzodioxoles by lead tetraacetate proceeds readily to
give 5-acetoxy and 5,6-dione derivatives as main products. 5,6-Diacetoxy
compounds and 5-carboxy derivatives are found in some instances as minor
products. Oxidation of benzodioxoles substituted at the 5 and 6 positions with methoxyl groups or with a second dioxole ring results in
oxidative loss of the dioxole ring. Relative effects of these substitutions on
reactivity have been evaluated. The mechanism of o-quinone formation is
discussed and is postulated to occur via a tetraacetoxy intermediate. The
5-acetoxy derivatives and the o-quinones, by hydrolysis and reduction
respectively, serve as sources of 5-hydroxy and 5,6-dihydroxy benzodioxoles.
Synthesis of N-methyl-N-(2,2,2-trichloro-1-arylaminoethyl)formamides and related compounds as potential fungicides
Authors: Grant HG , Summers LA
Published: September 2010

The synthesis of several
analogues of the chloralformamide fungicides is
reported. The compounds, which comprise N-methyl-N-(2,2,2-trichloro- 1-arylaminoethyl)formamides
and related alkoxyethyl and aryloxyethyl derivatives, exist at room temperature
as two isomers due to restricted rotation about the C-N amide bond. The results
of their evaluation as fungicides are reported.
Studies of Australian soft corals. XVIII. Further cembranoid diterpenes from soft corals of the genus Sarcophyton
Authors: Bowden BF , Coll JC , Mitchell SJ
Published: September 2010

The structure of two new
cembranoid diterpenes, (E,E,E)-7,8-epoxy-1- isopropyl-4,8,12-trimethylcyclotetradeca-1,3,11-triene
(2) and (E,E,E)- 7,8-epoxy-1-isopropenyl-4,8,12-trimethylcyclotetradeca-1,3,11-triene
(4), are reported. These two diterpenes (2) and (4) co-occur with the known
cembranoid diterpene alcohol (3), sarcophytoxide (5) and sarcophine (6) in the
same specimen; this enables a scheme for the biological interconversions of
isoneocembrane A (1) to sarcophine (6) to be suggested.
The reaction of methyl 4,6-O-isopropylidene-2,3-O-thiocarbonyl-α-D-mannoside with methyl iodide : a synthesis of methyl α-Tyveloside (methyl 3,6-dideoxy-α-D-arabino-hexopyranoside)
Authors: Patroni JJ , Skelton BW , Stick RV , White RV
Published: September 2010

The reaction of methyl 4,6-O-isopropylidene-2,3-O-thiocarbonyl-α-D- mannoside with methyl iodide gives two major products,
methyl 3,6- dideoxy-3,6-diiodo-2-O-(methylthio)carbonyl-α-D-altro-pyranoside and methyl
2,3-O-carbonyl-6-deoxy-6-iodo-α-D-mannopyranoside, both of which lack the
4,6-O-isopropylidene grouping but contain the 6-deoxy-6-iodo function, and
another minor product. One of the major products, methyl 3,6-dideoxy-3,6-diiodo-2-O-(methylthio)carbonyl-α-D-altro-pyranoside, is converted into methyl α-tyveloside
by sequential reduction and ester removal. The incorporation of iodine at C6 is
seemingly due to hydrogen iodide, and may be suppressed in the presence of
N,N,N,N- tetramethylnaphthalene-1,8-diamine or propylene oxide, or by the use
of 4,6-O-benzylidene-2,3-O-thiocarbonyl-α-D-mannoside as substrate. Methyl
iodide/propylene oxide is apparently an efficient combination for thiocarbonate
(C=S) into carbonate conversion. The structure of the minor product was shown
by single-crystal X-ray diffraction to be 1,6- anhydro-3-deoxy-3-iodo-2-O-(methylthio)carbonyl-β-D-altropyranose.
Stereochemical studies. VII. Synthesis and deamination of stereoisomeric 2-Aminodecahydronaphthalen-1-ols
Authors: Lewis PH , Middleton S , Rosser MJ , Stock LE
Published: September 2010

When treated with nitrous
acid, the trans-fused amino alcohol (3) undergoes 'normal' stereospecific
deamination to give the trans-fused octahydroindene-1-carbaldehyde (20) in
contrast with the reported 'abnormal' behaviour of the related amino sterol
(1).
Chemistry of pyrrolic compounds. XLVI. Benzyl β-keto propionate porphyrins: a new synthesis of deoxophylloerythroaetioporphyrin and harderoporphyrin
Authors: Chaudhry IA , Clezy PS , Mirza AH
Published: September 2010

Porphyrins with benzyl
β-keto propionate side chains have been prepared by condensation of the
appropriate porphyrin acid chloride with the magnesium chelate of the enolate
form of benzyl hydrogen malonate. Intermediates of this class have been used in
the synthesis of deoxophylloery-throaetioporphyrin
and harderoporphyrin.
Diorganotin(IV) derivatives of monothio β-diketones
Authors: Saini SK , Gupta VD , Mehrotra RC , Tripathi RP
Published: September 2010

Diorganotin(IV) derivatives
of monothio β-diketones of the general formula R2Sn(R'CSCHCOR')2
(R = Me, Bu, Ph; R' = Ph, Me; R'' = Ph, p-FC6H4, 2-F,4-OMeC6H3)
have been synthesized by the reactions of R2SnCl2 or R2SnO
with monothio β-diketones. Complexes of the type, SnX2(R'CSCHCOR')2
(X = Cl, Br, OAc), have
also been synthesized. These compounds have been characterized by element
analyses as well as by i.r., 1H n.m.r.,
and Mossbauer spectra. Ebullioscopic molecular weight determinations show them
to be monomeric in benzene.
A novel preparation of quaternary 'hexamminium' salts
Authors: Morgan KR , Curtis NF
Published: September 2010

Quaternary hexamminium
salts (salts of N-alkyl-1,3,5,7- tetraazaadamantane cations) are readily prepared
by condensation of the alkylammonium salt (most satisfactorily the
perchlorate), ammonia and formaldehyde.
The behaviour of the lead-aqueous sulfate electrode in relation to the development of electric vehicle batteries
Authors: Matthews DB , Garrad RW
Published: September 2010

The behaviour of smooth
lead electrodes in various aqueous sulfate electrolytes has been studied by
slow scan (10 mV min-1) cyclic voltammetry and coulometry and by
scanning electron microscopy. The dependence of the amount of charge that can
be delivered in discharge of lead to form lead sulfate, as in a lead-acid
battery, is found to depend strongly on electrolyte composition, and an acidic
ammonium sulfate electrolyte (0.5 mol dm-3, pH 2.0) was found to
yield the highest charge over some 40 charge-discharge cycles when compared
with various other sodium sulfate, ammonium sulfate and sulfuric acid
electrolytes. The quantity of charge was directly related to the size of the lead
sulfate crystals produced. This result is interpreted in terms of the passivating
effect of lead sulfate. A tentative mechanism for the anodic formation of lead
sulfate is proposed and used to interpret the cyclic voltammograms obtained in
concentrated sulfuric acid.
Pressure- and temperature-dependent isomerization reactions of aquabis(ethylenediamine) cobalt(III) complexes: deuterium solvent isotope effects
Authors: Lawrance GA , Suvachittanont S
Published: September 2010

The pressure and temperature
dependence of the trans → cis isomerization reaction of trans-Co(en)2(X)(OH2)n+
(X = OH2, OSeO2H- or AcO-;
en = ethane-1,2-diamine) has been determined in D2O, and compared
with results previously determined in H2O under analogous conditions
of acidity and ionic strength. Generally positive activation volumes (ΔV‡)
and activation entropies (ΔS‡) in both solvents are consistent
with a dissociative mechanism with aqua ligand release in the activated state.
Isomerization in D2O is characterized by slightly higher ΔH‡
and ΔS‡ values and a less positive ΔV‡ value in
each case. The clear change in ΔV‡ from H2O to D2O
supports the existence of an appreciable contribution from solvent
rearrangement in forming the activated state to the activation volume.
Variations in solvent structure and ionic solvation apparently account for the
deuterium solvent isotope effect.
Tracer diffusion coefficients of tritiated water and acetonitrile in water + acetonitrile mixtures
Authors: Easteal AJ
Published: September 2010

Tracer diffusion
coefficients of tritiated water (HTO) and 14C-labelled acetonitrile
have been measured at 298.15 K by the diaphragm cell method, for the whole
range of compositions of water+ acetonitrile binary mixtures. The composition
variation of (a) the deviation of D from additivity and (b) the product Dη, for each component, has been evaluated. The
variation of Dη is discussed in terms of the Naberukhin- Rogov structural
model for solutions of non-electrolytes in water. ��� The diffusion data have been used to test a
semiempirical relationship, between solution viscosity and self-diffusion
coefficients, due to Albright. For the composition region of 5-55 mole %
acetonitrile Albright's equation gives calculated viscosities which agree well
with observed values. The calculation fails to reproduce the observed variation
of viscosity for the composition region of 60-95 mole % acetonitrile.
Generalized van der Waals theory. II. Quantum effects on the equation of state
Authors: Hooper MA , Nordholm S
Published: September 2010

The light gases deviate
markedly from the Law of Corresponding States approximately obeyed by the
heavier gases. This is due, at least in part, to the quantization of
translational motion at higher densities. This effect has been studied within
the framework of a generalized van der Waals model. Each particle is treated as moving within a
cubic volume determined by the surrounding particles. Changes to the critical
parameters and to the shapes of the coexistence and vapour pressure curves are
calculated and compare well with experiment, considering the simplicity of our
model.