bluuebunny/crossref_metadata_2025 huggingface dataset:
Aluminium corrosion studies. IV. Pitting corrosion
Authors: Lowson RT
Published: September 2010

Measurements are reported
for the variation of the open-circuit potential, Er, of aluminium in
oxygen-saturated sodium salt solutions. The value of Er was
independent of SO42- and NO3-
concentrations and similar to the value obtained for water (0.04 (s.h.e.)). Er was a function of chloride
concentration given by
������������������� Er =
-0.475-0.060log[Cl-] V (s.h.e.)
at 25�C. There was a less
well defined relationship between Er and NO2-,
I- and Br-, and a complex relationship with F-.
��� The potentiodynamic characteristics are
reported for aluminium in 1-0.01 mol l-1 Cl-
oxygen-saturated solutions. Functional relationships were found for E0,
Ep, Es and E0' with chloride activity at 5,
25, 50 and 75°C. Hysteresis effects are reported. ��� The experimental results are interpreted in
terms of a thermodynamic equilibrium condition between the surface oxide and
soluble aluminium chloride. As the system oscillates across the equilibrium
conditions the surface will passivate or pit. A critical bulk solution chloride
concentration is necessary to maintain the growth of the pit; the experimental
value was 1.6 mol l-1 Cl- and
the corresponding open-circuit potential was Ecrit = -0.48 V (s.h.e.). The pitting potential, Ev, was interpreted
as an overpotential, ηp, given by η = Ep,- Ep-Ecrit.
The crystal and molecular structure of [2,2]Metacyclophan-1-ene
Authors: Taylor D
Published: September 2010

Crystals of
[2,2]metacyclophan-1-ene, C16H14, are orthorhombic, with
a 10.932(1), b 17.336(1), c 12.089(1) Ǻ, space group Pbca
and Z 8. The structure was solved from diffractometer data [1055 independent
reflections with I ≥ 3σ(I)] by direct methods. Full-matrix least- squares
refinement of all atoms converged at R 0.047, Rw 0.033. The aromatic
rings exhibit distortions from planarity with a maximum deviation of 0.16
Ǻ; these distortions are due to the short C...C contact of 2.59 Ǻ
between the benzene rings.
Vinylindenes and some heteroanalogues in the Diels-Alder reaction. V. 3-Vinylindoles and quinones
Authors: Bergamasco R , Porter QN , Yap C
Published: September 2010

3-Vinylindoles give adducts
containing a benzo- or naphtho-carbazole ring system
by 1,4-cycloadditionsto 1,4-benzoquinone and 1,4- naphthoquinone respectively.
The adducts are readily dehydrogenated to the corresponding heterocyclic
quinones. No skeletal rearrangement accompanies oxidation with oxygen in base.
Tautomerism of Pyrazolidine-3,5-diones. III. Nuclear magnetic resonance spectra
Authors: Woodruff M , Polya JB
Published: September 2010

The tautomerism of some N1-
and N1,N2-substituted pyrazolidine-3,5-diones has been
studied by N.M.R. spectroscopy. The diketo form is the only unambiguously
detectable tautomer of N-phenylpyrazolidine-3,5-diones in CDCl3 and
(CD3)2SO whereas N-(1H-1,2,4-triazol-5-yl)pyrazolidine- 3,5 diones exist as
a mixture of the diketo form with other tautomers. Polar solvents shift the
equilibrium towards the keto-enol form; the diketo form is favoured at raised
temperatures.
The Hepta(μ-benzenethiolato)pentametallate(I) dianions of copper and silver: Formation and crystal structures
Authors: Dance IG
Published: September 2010

The yellow complexes (Me4N)2Cu5(SPh)7 and (Me4N)2Ag5(SPh)7, soluble in aprotic solvents, have been
synthesized. Crystal structure results are: (Me4N)2Cu5(SPh)7, a 12.250(1), b 20.151(4), c 11.531(2)
Ǻ, α 103.50(1), β 90.01(1), γ 83.20(1), space group Pī, Z 2, 3639 reflections (Mo Kα),
full anisotropic refinement, R 0.051; (Me4N)2Ag5(SPh)7, a 12.393(1), b 20.633(4), c 11.674(1)
Ǻ α 103.88(1), β 90.35(1), γ 82.96(1)°, space group Pī, Z 2, 6400 reflections (Mo Kα),
full anisotropic refinement, R 0.030. The crystals are isostructural. ��� The crystals contain a molecular cluster [M5(SPh)7]2-, the structure of which may
be visualized in terms of the array of metal atoms which is formed by addition
of a unique fifth metal atom over one elongated edge of an approximate
tetrahedron of metal atoms. Benzene thiolate ligands bridge the seven edges of
the resulting polyhedron of metal atoms. The four metal atoms derived from the
tetrahedron possess approximately trigonal planar coordination, while the
unique metal atom has approximately linear (S-M-S 175.2° (Cu), 176.0° (Ag))
digonal coordination. There is no evidence of strong metal-metal bonding in the
M5S7 core, which has very approximate C2v
symmetry. Average bond lengths are Cudig-S, 2.160; Cutrig-S,
2.270; Agdig-S, 2.361; Agtrig-S, 2.502 Ǻ.
The ionization and dissociation of triphenylmethyl chloride in 1,2-dichloroethane-styrene mixtures
Authors: Bos SS , Treloar FE
Published: September 2010

Triphenylmethyl chloride
with mercuric chloride ionizes and dissociates in 1,2-dichloroethane and 1,2-dichloroethane-styrene
mixtures into ion pairs and free ions. The values of the equilibrium constants
for ionization to ion pairs and the subsequent dissociation of these show that
the free ions are preferentially solvated by the added styrene. The
consequences of this for the cationic polymerization of styrene are briefly
discussed.
Pyrimidine N-oxides. I. The synthesis and some reactions of N-hydroxybarbiturates
Authors: Cowden W , Jacobsen N
Published: September 2010

A series of
5,5-disubstituted N-hydroxybarbituric acids has been prepared by direct
oxidation of their amino precursors, followed by hydrolysis. The behaviour of
the N-hydroxybarbiturates towards alkylating and reducing reagents is reported.
The reactions of a representative 5-monosubstituted N-hydroxybarbituric acid
indicate that the compounds of this series are chemically distinct from their
5,5- disubstituted homologues.
Stability Constants of Some Metal Complexes Formed by Mimosine and Related Compounds
Authors: Stunzi H , Perrin DD , Teitei T , Harris RLN
Published: September 2010

Complex formation of the
biologically active amino acid L-mimosine [α-amino-β-(3-hydroxy-4-oxo-1,4-dihydropyridin-1-yl)propanoic
acid (1)], mimosinic acid (2), mimosine methyl ether (9) and
3-hydroxy-1-methylpyridin-4(1H)-one
(4) with Cu2+, Zn2+, Cd2+ and Pb2+
was studied. Stability constants were determined by potentiometric titration in
0.15M KNOB3 as inert electrolyte at 37�. In the monomeric
complexes formed by the mimosine derivatives, metal binding by the hydroxypyridone
moiety was favoured relative to the amino acid group. With mimosine, dimeric
complexes were major species. Under physiological conditions, mimosine binds
copper and zinc ions more strongly than do simpler amino acids.
A Mechanism for Non-Flame Atomization in Atomic Absorption Spectroscopy
Authors: Byrne JP
Published: September 2010

A mechanism for atom
formation in non-flame atomizers, used in atomic absorption spectrophotometry,
is presented. The model assumes that gas-phase metal atoms are produced by the
direct thermal reduction of metallic oxides, produced as intermediates in the carbon
furnace. This mechanism does not assume that carbon is involved in the
reduction step. The minimum appearance temperatures for 15 elements are
calculated from equilibrium atom concentrations and free energy data. The
calculated appearance temperatures are found to correlate with the
experimentally determined values for these elements.
Stoichiometry and Kinetics of the Cobalt(III) Oxidation of Acetamide, Formamide, N-Methylformamide and N,N-Dimethylformamide in Acid Perchlorate Solutions
Authors: Ahmad F , Baswani VS
Published: September 2010

The oxidation of acetamide, formamide, N-methylformamide and N,N-dimethylformamide by cobalt(III) in perchloric
acid at 20°C has been investigated. The reaction requires nearly three moles of
cobalt(III) for one mole of amide (except acetamide)
and nearly one mole of cobalt(III) is consumed per mole of acetamide,
and leads in each case to the formation of the respective amines. The oxidation
of the amides is found to obey the rate law
-d[CoIII]/dt = (k' + k''[H+])[Co3+]
A free-radical mechanism
has been proposed for the reaction. Activation energies and entropies are
calculated for each reaction.
Covalent Addition of Bisulfite Ion to N-Alkylated Uracils and Thiouracils
Authors: Pitman IH , Jain NB
Published: September 2010

Rate and equilibrium
constants at 25� and I 1.0 M have
been calculated for the covalent additon of bisulfite ion across the C6=C5
double bond of uracil, 1-methyluracil, 1,3-dimethyluracil, uridine, uridine-5'-diphosphate
(dianion), adenylyl(3'-5')uridine, uridylyl(3'-5')adenosine, 2-thiouracil and 1,3-dimethyl-2-thiouracil.
Substitution of either uncharged (e.g. ribose) or charged (e.g. ribose 5'-diphosphate
dianion) groups for the N1 proton of uracil resulted in a small reduction in
both the rate and equilibrium constants for the formation of the adduct but had
very little effect on the rate of elimination of bisulfite ion from the adduct.
On the other hand, substitution at N3 of uracil substantially reduced both the
rates of formation and decomposition of the covalent adduct. The rates of
formation of the covalent adducts of 2-thiouracils were faster than those of
the uracil adducts but alkyl substitution produced similar decreases in the
magnitudes of rate and equilibrium constants.
Tetraalkylammonium Bromochlorocuprates(II)
Authors: Smith DW , Yeoh T
Published: September 2010

(NMe4)2CuBrnC14-n
and (NEt4)nCuBrnCl44-n (n = 1, 2, 3) have been
prepared and characterized by X-ray powder diffraction and far-infrared
spectroscopy. The tetramethylammonium compounds are
isomorphous with each other and with the corresponding compounds where n = 0,
4. The tetraethylammonium compounds constitute
another isomorphous series. All the compounds apparently contain discrete CuBrnCI4-n2-
anions, with flattened tetrahedral configurations.
The Absolute Configuration at C24 of the Ecdysteroids Dacrysterone, Pterosterone and Ponasterone C
Authors: Blunt JW , Lane GA , Munro MHG , Russell GB
Published: September 2010

The shielding values in 13C
N.M.R. spectra of the ecdysteroids dacrysterone, pterosterone, and ponasterone
C have been assigned, together with those for the 20,22- and 22,24-benzylidene
acetal derivatives of the latter. From the N.M.R. data the C24 configuration of
dacrysterone is assigned as 24R, while the 24s configuration is assigned to
pterosterone and ponasterone C.
Oxidation of Copper Sulfides in Aqueous Ammonia. II. Electrochemical Aspects
Authors: Filmer AO , MacLeod ID , Parker AJ
Published: September 2010

The oxidation of covellite,
CuS, to copper(II) and sulfur or sulfate ions in aqueous ammonia is slowed by
the formation of an equilibrium thickness of a copper polysulfide Cuss (y < 1). The polysulfideis thermally and
electrochemically unstable when in contact with CuS. A surface coating of
sulfur, although formed, is not responsible for the semi-passivation of CuS
during oxidation. Cyclic voltammetry, controlled potential electrolysis, linear
sweep voltammetry, and various amperiometric and coulometric experiments with
electrodes of pressed CuS, of carbon paste containing CuS and or a carbon ring
with a CuS disc have been used to study the formation or decomposition of Cuss
and its effect on rates of oxidation or CuS in aqueous ammonia. CuS-carbon
paste electrodes offer some advantages over pressed discs of CuS for such
studies.
Rearrangements in the Furan Series. II. The Reaction Between Furfuraldehyde and Aromatic Amines
Authors: Lewis KG , Mulquiney CE
Published: September 2010

A survey of the reaction of
a variety of primary aromatic amines with furfuraldehyde
has shown that, in most cases, the product isolated has the
2,4-diarylaminocyclopent-2-enone structure as established in the case of
aniline. In a number of cases the products were shown to be the isomeric 4,5-diarylamino
derivatives. It has been established that the 2,4-diarylamino derivatives are
the more stable structures and that 4,5-disubstituted isomers are
intermediates. Treatment of the 4,5-diarylaminocyclopent-2-enones with mineral
acids gives a facile ring opening at room temperature to form the corresponding
Stenhouse salt. A mechanism is suggested for both the above reactions. The
results of some previous work are clarified.
Pyridinophane Bridging Group Chemistry: Synthesis and Reactions of 1,2,9,10-Tetra-chloro[ 2,2](2,6)pyridinophane-1,9-diene
Authors: Martel HJJB , McMahon S , Rasmussen M
Published: September 2010

Oxidation and polychlorination of 2,11-dithia[3,3](2,6)pyridinophane (II) gives high yields of the corresponding octachloro bissulfone (14) which,
on vacuum pyrolysis, readily loses SO2 and Cl2
sequentially, giving eventually a good yield of orange 1,2,9,10-tetrachloro[2,2](2,6)pyridinophane-1,9-diene
(4). Nucleophilic addition and substitution reactions of the dichloroethene bridges of (4) are described. None of the
[2,2]metacyclophane diene systems undergoes
spontaneous or photoinduced valence tautomerism to a 10b,10c-diazapyrene (2).
Synthesis and Reactions of Some para-Substituted N-Hydroxyacetanilides
Authors: Calder IC , Caciolli S
Published: September 2010

The synthesis of some
4'-protected N,4'-dihydroxyacetanilides
is described. The reactions of the N-acetoxy derivatives have been studied.
Tropolone Analogues of the Amino Acid Mimosine
Authors: Teitei T , Harris RLN
Published: September 2010

The synthesis of DL-α-amino-β-(4-hydroxy-5-oxocyclohepta-1,3,6-trienyl)propanoic acid (2) and the corresponding 6-hydroxy isomer
(3), tropolone analogues of the wool-growth
inhibiting amino acid mimosine (1),is described. Both
isomers were obtained in a single sequence, commencing with the cycloaddition
of dichloroketene to (β, β-diethoxyethyl)cyclopentadiene,
and were readily separated at an intermediate stage via the copper complexes.
A Convenient Synthesis of Psoralen Derivatives Oxygenated in the Pyrone Ring: 4-Methoxypsoralen and 3,4-Dimethoxypsoralen (Halkendin)
Authors: Ahluwalia VK , Prakash C , Singh RP
Published: September 2010

A convenient synthesis of psoralen derivatives oxygenated in the pyrone
ring, viz. 5-methoxy-7H-furo[3,2-g][l]benzopyran-7-one
(4-methoxypsoralen) and 5,6-dimethoxy-7H-furo[3,2-g][l]benzopyran-7-one
(3,4-dimethoxypsoralen or halkendin), has been
achieved by blocking the 8-position of the coumarin ring with an iodo group,
Claisen migration, and subsequent cyclization.
Ion Cyclotron Resonance Studies of Alkylsilyl Ions. II. The Reactions of Ketones, Carboxylic Acids and Esters with the Trimethylsilyl Cation
Authors: Blair IA , Bowie JH
Published: September 2010

Nucleophilic attack of a
ketone, carboxylic acid or ester at the electrophilic centre of the trimethylsilyl cation (Me,Si+)
produces a 1:1 adduct. This adduct does not decompose in the case of ketones.
Acid adducts decompose primarily by loss of methane, but a minor pathway exists
which involves elimination of a ketene. Ester adducts fragment primarily by
this latter process through a four-membered transition state. The transfer of
hydrogen was shown to arise solely from the acyl group and was shown to proceed
with a small deuterium isotope effect. Further decomposition of the resulting
ion by loss of methane provides unequivocal proof that esters react
predominantly through the alkyl oxygen with the Lewis acid Me3Si+.
Creation of a Simple Stable Enol. The Stabilizing Properties of the Diazonium Substituent
Authors: Ballard MJ , Bouma WJ , Radom L , Vincent MA
Published: September 2010

Ab initio molecular orbital theory is used to examine the effect of the diazonium substituent (N2+)
on the keto-enol equilibrium in the acetaldehyde/vinyl alcohol system. The conformational preferences
of the two isomers are examined, and optimized geometries obtained for the best conformers. The
diazonium substituent is a strong π-electron acceptor and σ-electron acceptor, and accordingly
destabilizes the keto isomer and stabilizes the enol isomer. The effect of the diazonium substituent
is sufficiently large to make the enol isomer substantially lower in energy than the keto isomer.
New Chemical Constituents sf Planchonia careya. II. Bark Constituents Soluble in Light Petroleum
Authors: Khong PW , Lewis KG
Published: September 2010

Examination of the light
petroleum extract of the bark of Planchonia
careya has led to the isolation of stigmasterol, a mixture of triterpene
monoketones and a series of triterpene diols including olean-18-ene-3β,28-diol (moradiol), and
olean-12-ene-3β,28-diol
(erythrodiol). Several minor constituents were also assigned as belonging to
the germanicol family.
Hydrogen Abstraction from Dimethyl Sulfide by Trifluoromethyl Radicals
Authors: Arthur NL , Yeo KS
Published: September 2010

Additional data are
presented for hydrogen abstraction from (CH3)2,S by CF3
radicals
CF3+(CH3)2S
→ CF3H+CH2SCH2 (1)
leading to a revised value
for the rate constant (k in cm3
mol-1 s-1, E in J mol-1): logk1 = (11�83�0�06)-(26910�450)/19.16T
Combination of these
results with thermochemical data gives a revised value of logk-1 = 11�9-61800/19�145Tfor the rate constant of
the reverse reaction.
Studies in the Tricyclooctane Series. III. Dehydrobromination of Some Bis-bromocarbene Adducts of Cyclohexadienes
Authors: Banwell MG , Halton B
Published: September 2010

Treatment of
4,4,8,8-tetrabromo-cis-transoid-cis-tracyclo[5,1,0,03,5]octane (If)
with potassium t-butoxide leads to mixtures of the (E)- and (Z)-isomers of 4- and 3-bronlo-β-t-butoxystyrene (5e,f) and
(9e,f) respectively, whereas the 4,4,endo-8-tribromo
analogue (1g) affords the parent styrenes
(5c,d). On the other hand the tetra- and tri-bromo-cis-transoid-cis-tricyclo[5,1,0,02,4] octanes
(8f-h)give complex and unresolved product mixtures. Evidence is presented which
eliminates the involvement of halogenocyclooctatetraenes
and p-halogenophenylacetylenes
in these reactions.
Studies of Australian soft corals. XVI. Two new sesquiterpenes from Lemnalia humesi
Authors: Bowden BF , Coll JC , Mitchell SJ
Published: September 2010

The isolation of two new sesquiterpenes containing the aristolane
skeleton, (4R,5S,6R,7S)-aristol-9-en-3-one (1) and (3S,4R,5S,6R,7S)-
aristol-9-en-3-ol (2), is reported from the soft coral Lemnalia
humesi. The structures were established
spectroscopically and confirmed by chemical conversion into (+)-aristol-9-ene
(3).
The Quinones of Nepenthes rafflesiana. The Crystal Structure of 2,5-Dihydroxy-3,8-dimethoxy-7-methylnaphtho-1,4-quinone (Nepenthone-E) and a Synthesis of 2,5-Dihydroxy-3-Methoxy-7-methylnaphtho-1,4-quinone (Nepenthone-C)
Authors: Cannon J , Lojanapiwatna V , Raston C , Sinchai W , White A
Published: September 2010

Plumbagin (1), droserone (2), hydroxydroserone (4) and four
new quinones, nepenthone-A, nepenth-one-B, nepenthone-C (17) and nepenthone-E
(9), have been isolated from the roots of Nepenthes rafflesiana
Jack. A fifth quinone-nepenthone-D-has been detected in the extract and has
been assigned the tentative structure (29) from its spectroscopic properties. ���
The crystal structure of nepenthone-E (9)
was determined by X-ray diffraction; diffractometer data at 295 K were refined
by full-matrix least squares to a residual of 0.061 (1040 'observed' reflections).
Crystals of nepenthone-E (9) are triclinic, Pī a
7.579 (4), b 7.764 (5), c 10.806 (7) Ǻ, α 70.86 (4), β 101.40
(5), γ 91.70 (5)°, Z 2. ���
The structure of nepenthone-C (17) has been
confirmed by an unambiguous synthesis. A synthesis of 2,7,8-trimethoxy-3-methyl-5,6-methylenedioxynaphtho-1,4-quinone
(49) has revealed that this substance (49) is not identical with the O,O-dimethyl
ether of nepenthone-A, and it is suggested that nepenthone-A is either the 5-
or 8-O-methyl ether of 2,5,8-trihydroxy-3-methyl-6,7-methylenedioxy-naphtho-1,4-quinone
[(36) or (37), respectively].
Predicting non-first-order behaviour in fully coupled 13C-1H spectra: a general rule
Authors: Jones AJ , Jenkins GA , Heffernan ML
Published: September 2010

The proton-coupled
carbon-13 n.m.r. spectra in ABCDX, ABCX and ABX spin systems are shown to be
non-first order when the condition 1JCH/2 = Δδ is met, where Δδ
is the proton chemical shift separation between two closely coupled protons
associated with adjacent carbon atoms. Solvent and temperature effects are
shown to be useful in removing the spectral complexity and thus assist in
complete analysis. Examples in heteroaromatic and hydrocarbon compounds are
presented. For a chosen solvent system the non-first-order behaviour may be
predicted from the 1H n.m.r. spectrum and used as an aid in 13C
n.m.r. spectral assignment.
Intramolecular hydrogen bonding in ortho-substituted N,N-dimethylbenzamides
Authors: Fong CW
Published: September 2010

Intramolecular hydrogen
bonding in o-hydroxy-, o-amino- and o-mercapto- N,N-dimethylbenzamide has been
examined with the help of 1H, 13C n.m.r. and infrared
spectroscopy, a study of barriers to rotation about the C- N bond, and a study
of substituent effects using a multi-substituent parameter equation. The cyclic
intramolecular hydrogen-bonded structure for the o-mercapto compound is
non-planar, and conformational isomers have been detected. The order of
relative energies of the hydrogen bonds formed in o-substituted N,N-dimethylbenzamides
is OH > NH2 > SH, as determined from a rotational barrier
probe. It has beenverified that intramolecular
hydrogen bonding causes a downfield shift of the 13C n.m.r. chemical
shift of the carbonyl group in these compounds.
Pattern recognition and interpretation of nucleoside mass spectra
Authors: Maclagan RGAR , Mitchell MJ
Published: September 2010

Four pattern-recognition
techniques-distance from the mean, the learning machine approach, a statistical
linear discriminant function analysis and the k-nearest-neighbour method-have
been applied to a set of 125 nucleoside mass spectra. Twenty-one structural
features, comprising elemental compositions and substitution types, were
predicted from binary and logarithmic transforms of the spectra. The best
classification was given by the distance from the mean method with logarithmic
data. With this method prediction success averaged 79 % over the 21 categories,
or in terms of the figure of merit 0.27.
1'-Derivatives of sucrose and their acid hydrolysis
Authors: Guthrie RD , Jenkins ID , Watters JJ
Published: September 2010

Syntheses of
1'-chloro-1'-deoxy- and 1'-deoxy-sucrose are described. Several routes were
investigated, the most successful being through
6,1',6'-tri-O-(2,4,6-trimethylbenzenesulfonyl)sucrose. Attempts to prepare
1'-deoxy-1'-fluorosucrose were unsuccessful. The rates of the acid-catalysed
hydrolysis of 1'-chloro-1'-deoxysucrose and of 1'- deoxysucrose have been
measured. These values are compared with that for sucrose itself. The mechanism
of the hydrolyses is discussed.
Excess volumes for binary liquid mixtures of 1-chlorobutane with normal alkanes
Authors: Krishnaiah A , Rao DN , Naidu PR
Published: September 2010

Excess volumes for binary
mixtures of 1-chlorobutane with hexane, heptane, octane and nonane were
measured dilatometrically at 303.15 K. Excess volumes
are positive over the entire range of composition in the four mixtures.
Further, it is observed that increase in chain length increases the magnitude
of the excess function.
Use of 2,4,6,-Trimethylbenzyl esters in the synthesis of tryptophan peptides
Authors: Rivett DE , Stewart FHC
Published: September 2010

Tryptophan peptides have
been obtained from the corresponding benzyloxycarbonyl peptide
2,4,6-trimethylbenzyl esters by catalytic hydrogenation. Associated reference
peptides were also prepared from 2,4,6-trimethylbenzyl precursors by either
hydrogenation or acidic cleavage of the protecting groups.
Central nervous system active compounds. IV. Synthesis of 3-aminobenzylphthalides
Authors: Hutchison GI , Marshall PA , Prager RH , Tippett JM , Ward AD
Published: September 2010

Several
3-aminobenzylphthalides have been prepared by reactions of 3-
(2-oxo-1-phenylpropyl)-phthalides with hydrazoic acid or by the Beckmann
rearrangement. The corresponding reactions with 3-(2- oxoindanyl)phthalides
showed limited success but led to a new synthesis of phthalide-isoquinoline
alkaloids. Preliminary biological testing of some of these derivatives
indicates that they only have weak central nervous system activity.
An ab initio and ion cyclotron resonance study of the reactions between alkoxide negative ions and silane systems. Stable adduct formation, and nucleophilic displacement reactions
Authors: Klass G , Trenerry VC , Sheldon JC , Bowie JH
Published: September 2010

Ab initio LCAO-MO-SCF calculations suggest that reaction of HO-(or
MeO-) with silane should proceed through a stable trigonal
bipyramidal adduct. Reaction of alkoxide anions with a variety of alkylsilanes
in an i.c.r. spectrometer leads to (i) nucleophilic displacement reactions,
(ii) stable adducts, (iii) decomposing adducts which collapse to tetrahedral
anions by elimination of a neutral molecule, and (iv) proton abstraction
reactions. The nucleophilic displacement reaction between MeO- and
Me3SiR has been used to produce a variety of R- species,
including the allyl, propargyl and benzyl anions. The reactions of these ions
with methyl nitrite have been used to show that (i) the benzyl anion does not
undergo benzylic hydrogen/phenyl hydrogen scrambling prior to reaction, (ii)
the allyl anion reacts as a symmetrical species, and (iii) that hydrogen
scrambling does not occur in the propargyl anion, and that C3H3-
may either react as HC≡C-CH2- or -HC=C=CH2.
Synthetic uses of the sequential ring positional reactivity in Pyridin-3-ol and derivatives
Authors: Clark GJ , Deady LW
Published: September 2010

A series of
ring-substituted pyridin-3-ols has been prepared. The key to the scheme is the
introduction of a bromo group to a specific ring position as a temporary
blocking agent. As well as hydrogenolysis of the bromo function, nucleophilic
displacement has also been investigated.
Synthesis of unlabelled and carboxyl-labelled 3-Amino-5-hydroxybenzoic acid
Authors: Herlt AJ , Kibby JJ , Rickards RW
Published: September 2010

Efficient syntheses are
reported of the natural amino acid 3-amino-5-hydroxybenzoic
acid in unlabelled and carboxyl-labelled forms from 3,5-dinitrobenzoic acid
and 3,5-dinitroanisole, respectively.
Studies of Australian soft corals. XXIV. Two cembranoid diterpenes from the soft coral Sinularia facile
Authors: Bowden BF , Coll JC , Mitchell SJ , Kazlauskas R
Published: September 2010

Extraction of the soft
coral Sinularia facile afforded two cembranoid diterpenes whose structures and
absolute configurations have been determined as
(1R,4R,2E,7E,11E)-cembra-2,7,11-trien-4-ol (1) and (1R,3S,4S,7E,11E)-3,4-epoxycembra-7,11,15-triene
(2).
Studies on the total synthesis of gibberellins. A new strategy for A-ring construction
Authors: Blair IA , Mander LN , Mundill PHC , Pyne SG
Published: September 2010

3-(4',6'-Dimethoxynaphthalen-1'-yl)propanoic acid (10) was transformed to 8-methoxy-5-(3'-oxo-
butyl)-1,2,3,4-tetrahydronaphthalene-2-carboxyic acid (8) and its 2-hydroxy
derivative (9) by conventional synthetic reactions. Acid-catalysed cyclization
of the derived diazomethyl ketones (23), (24) and
(25) led to dienones (26), (27) and (28) which
readily underwent base-catalysed 1,4-conjugate addition to provide the hydroethanophenanthrenetriones (30), (31) and (32)
respectively.
Transition metal mediated asymmetric synthesis. II. Complete resolution of (2R,5S)-(-)-Tricarbonyl[1-5-η-(2-methoxy-5-methylcyclohexadienyl)]iron(1+) hexafluorophosphate(1 -) by selective crystallization of enantiomers
Authors: Stephenson GR
Published: September 2010

The resolution of tricarbonyl(1-5-η-cylcohexadienyl)iron(1+) salts can
be achieved by selective crystallization of enantiomers.
The magnitude of the specific rotatory power of the
title salt (1) was increased to a limiting value which was shown to correspond
to optical purity, by a direct, n.m.r. method, after alkylation with dimethyl malonate. Reduction of the optically active salt defined
the absolute configuration of (2R,5S)-(+ )-tricarbonyl[l-4-η-(2-methoxy-5β-methylcyclohexa-1,3-diene)]-iron(0).
The chiroptical properties of the products are
discussed.
Moulting Hormones. LIII. the Synthesis and Biological Activity of Some Ecdysone Analogues
Authors: Galbraith M , Horn DS , Kelly B , Kinnear J , Martin M , Middleton E , Virgona CF
Published: September 2010

A number of ecdysone
analogues were prepared to study the effect of structural changes on biological
activity. It was found that analogues with the 5α-configuration or a
3,5-cyclo structure were inactive, that a 3β-hydroxy group enhances
activity but is not essential for activity, and that 3β-substituents
decrease activity as follows: OMe (60%), OAc (25%) and OEt (10%). The keto diol
(3), keto alcohol (9) and amide (36) were found to be highly toxic to mosquito
larvae.
Rate enhancement of the nickel(II)-pada complex formation in sodium alkanesulfonate micellar solutions
Authors: Hicks JR , Reinsborough VC
Published: September 2010

Sodium alkanesulfonates (C9, C8, C7,
and C6) in micellar solution have been used to enhance the rate
of reaction between Niaq2+ and the bidentate ligand
pyridine-2-azo-p-dimethylaniline
(pada) at 298.2 K. A Berezin-like model has been used to account for the
observed kinetic constants in terms of the binding constants of each of the
reagents to the micelles and the reaction volume and the concentration of the
micellar surfactant. For a given chain length, the alkanesulfonates are about
25 % less effective than alkyl sulfates in promoting the rate of reaction and
the model accounts for this successfully.
Chemistry of the Podocarpaceae. LIX. Dimerization of a Favorski-type rearrangement product
Authors: Cambie RC , Robertson JD , Rutledge PS , Woodgate PD
Published: September 2010

Ozonolysis of podocarpic acid (1)
followed by reduction of the resulting hydroperoxide (16) gives a moderate
yield of the keto diacid (6). Treatment of the
derived 7α-bromo keto acid (10) with potassium carbonate in acetone
effects a Favorski-type rearrangement with decarboxylation to give the
methylene ketone (15); the latter dimerizes in hot
ethanol to give a quantitative yield of (29).
A brominated metabolite from the red alga Vidalia spiralis
Authors: Kazlauskas R , Murphy PT , Wells RJ
Published: September 2010

3,4-Dibromo-5-methylenecyclopent-3-ene-1,2-diol
has been isolated from a Western Australian collection of the red alga Vidalia spiralis.
Hydroxy sulfoxides derived from norbornene: determination of stereochemistry, and synthesis by stereoselective oxidation
Authors: Beckwith ALJ , Rodgers JR , Wagner RD
Published: September 2010

The structure (5) of one of
the hydroxy sulfoxides formed by thiol-oxygen cooxidation of norbornene has
been determined by X-ray diffraction. Other products have been related to it by
appropriate chemical transformations. The stereospecific, or highly stereoselective,
conversion of suitable hydroxy sulfides into one of the two possible
diastereoisomeric hydroxy sulfoxides demonstrates the directive influence of
the hydroxyl group on oxidation of vicinal sulfur.
Synthesis of 1-, 6- and 1,6-derivatives of methyl D-fructofuranosides
Authors: Guthrie RD , Jenkins ID , Yamasaki R
Published: September 2010

A variety of derivatives of
methyl α- and β-D-fructofuranosides modified at C1 or C6, or at C1
and C6, have been prepared in which the hydroxyl group(s) has been replaced by
azido, amino, chloro, bromo, hydrogen and thiol acetate functions. These
compounds were made by displacements on methyl 1,6-di-O-p-toluenesulfonyl-D-fructofuranosides, or on 2,3-O-isopropylidene-l,6-di-O-p- toluenesulfonyl-β-D-fructofuranose
and subsequent glycosidation. A number of indirect methods of preparation of
methyl D-fructofuranosides, mostly based on 1,3,4,6-tetra-O-benzoyl-D-fructofuranose have been investigated.
Tritium gas exchange with aromatic and aliphatic hydrocarbons over metal containing ZSM-5 and related zeolites
Authors: Long MA , Garnett JL , Williams PG
Published: September 2010

Platinum
and palladium containing Y-zeolite, mordenite and ZSM-5 catalyse
efficient exchange at 100°C between elemental tritium and aromatic or aliphatic
hydrocarbons, the tritium orientation in the organic molecule showing
characteristics of both metal and zeolite catalysis.
The hydrogen forms of the same zeolites (i.e. without
metal) also activate elemental tritium for aromatic exchange at 120-150�C,
which shows that a metal component is not necessary for activation of elemental
hydrogen even at modest temperatures.
The nitration of 1,2,3,4-tetramethyl-5,6-dinitrobenzene; X-ray crystal structure of cis-2,5,6,6-Tetramethyl-2,3,4,5-tetranitrocyclohex-3-enone
Authors: Gray MJ , Hartshorn MP , Richards KE , Robinson WT , Sutton KH , Thompson RS , Vaughan J
Published: September 2010

Nitration of
1,2,3,4-tetramethyl-5,6-dinitrobenzene (1) with fuming nitric acid in
dichloromethane gives cis-and trans-2,5,6,6-tetramethyl-2,3,4,5-tetranitrocyclohex-3-enones
(9) and (10), the structure of the cis
isomer being confirmed by X-ray crystal structure analysis. The mechanism of
formation of tetranitro ketones (9) and (10) is
discussed.
Solar reduction of water. III. Improved electron-transfer agents for the system water-Tris(2,2'-bipyridine)ruthenium dication-ethylenediaminetetraacetic acid-platinum
Authors: Launikonis A , Loder JW , Mau AWH , Sasse WHF , Summers LA , Wells D
Published: September 2010

In searching for more
effective electron-transfer agents for the photochemical production of hydrogen
by the title system 16 diquaternary pyridinium compounds have been evaluated. At pH values of
5.0 and 7.0 the best results are obtained with compounds with potentials near
-0.5 and -0.6 V, respectively, provided they are stable. Kinetic measurements
show that the rate of quenching of *Ru(bpy)32+ decreases and the rate of the
catalysed reduction of Haq+
increases as the potential becomes more negative, so that a range of optimum
potential is created. The pH dependence of hydrogen formation arises from the
effects of pH on the rate of reduction of Haq+.
The main loss of diquaternary pyridinium
compounds during irradiation is caused by catalytic hydrogenation. Therefore
compounds that are more resistant to hydrogenation than methylviologen
are more effective in the production of hydrogen, provided their potentials
fall within the required range.
Ring current shielding and molecular motions in Piperazine-2,5-diones
Authors: Frigerio IJ , Rae ID , Wong MG
Published: September 2010

In 3-(phenylmethyl)piperazine-2,5-dione
(cyclo(Phe-Gly)) the C6 methylene hydrogens are shielded by the aromatic ring
which lies above them. As the temperature is raised, this shielding is reduced
but the aromatic ring retains its gross position with respect to the methylene.
The reduction in shielding is believed to be caused by aromatic ring torsional
vibrations, enhanced at higher temperatures, which cause the aromatic ring to
spend less time face-on to the methylene. In the naphthalene analogue these vibrations
are damped and the shielding is less dependent upon temperature.
Synthesis of the cyclopropa[c]benzofuran system of mycorrhizin A and of gilmicolin from a benzofuranol. Crystal structure of a 5,8-Methanocyclopropa-[c]naphtho[2,3-b]furan derivative
Authors: Brown RFC , Fallon GD , Gatehouse BM , Jones CM , Rae ID
Published: September 2010

The cyclopropa[c]benzofuran derivative (17), which contains the structural
features of methyl ethers of mycorrhizin A and gilmicolin save for the C3 side chain, has been
synthesized from the benzofuranol (4) through the
benzofuran-4,7-dione (5) and the 7a-methoxy derivative (8). The cyclopropane ring of (17) was introduced by ultraviolet
irradiation of a 1-pyrazoline (13) at -78�; irradiation at room temperature
gave mainly a profoundly rearranged acidic product for which the methanoindenone structure (18) is proposed. The stereochemistry
of the penultimate cyclopropane (16) has been
established by X-ray crystallography.
The preparation of sodium 4-Amino-3-nitro-benzenesulfonate and some related compounds
Authors: Rosevear J , Wilshire JFK
Published: September 2010

The
sodium salt of 4-amino-3-nitrobenzenesulfonic acid (O-nitroaniline-p-sulfonic
acid) has been prepared by the action of dilute sodium
hydroxide solution on ethyl [(4-chlorosulfonyl-2-nitro)-
phenyllcarbamate.
Central to this synthesis is the finding that the N-ethoxycarbonyl group, when located ortho to
a nitro group (but not to a bromo group), is readily removed by dilute sodium hydroxide
solution.
Benzannelated 9-hydroxyphenalenones
Authors: Haddon RC
Published: September 2010

The preparation and characterization of the two title compounds (6-hydroxybenz[de]anthracen-7-one
(2) and 3-hydroxybenz[de]anthracen-4-one(3) or their proton tautomers), and an isomer (8-hydroxybenz[
de]anthracen-7-one (4)), are reported. The electronic spectra of (2) and (3) suggest that annelation
of 9-hydroxyphenalenone (1) produces substantial shifts in the energies and intensities of
the transitions, but does not fundamentally alter the underlying character of the chromophore.
Studies of Australian soft corals. XXIX. Several new cembranoid diterpenes from Nephthea brassica and related diterpenes from a Sarcophyton species
Authors: Blackman AJ , Bowden BF , Coll JC , Frick B , Mahendran M , Mitchell SJ
Published: September 2010

The
isolation of five known cembranoid diterpenes, (1), (2), (3), (4) and ( 5 ) , is
reported from the soft coral Nephthea brassica. These
diterpenes co-occur with several new but related diterpenes:
(13S)-cembra-1,3,7,11-tetraen-13-ol (6)
and its corresponding 13-acetate (7), 15-acetoxycembra-3,7,11-triene (8), (10S)-10,15-diacetoxy-7,8-epoxycembra-3,11-diene
(9) and its corresponding 10-monoacetoxy derivative (10).
Two related cembranoid diterpenes, (14S)-acetoxycembra-1,3,7,11-tetraene (15)
and (14S)-cembra-1,3,7,11-tetraen-14-01 (16),
are reported from a soft coral of the genus Sarcophyton.
Synthesis of some 2,5-benzoxazocine and 2,6-benzoxazonine derivatives from ω-(Dihydroisoindol-2-yl)alkanol precursors by means of cyanogen bromide
Authors: Bremner JB , Thirasasana N
Published: September 2010

Reaction of cyanogen
bromide with 2-(1-phenyl-2,3-dihydro-1H-isoindol-2-yl)ethanol (5a) gave
1-phenyl-3,4,5,6-tetrahydro-1H-2,5-benzoxazocine-5-carbonitrile (6a) in a low
to moderate yield. Similarly,
3-(1-phenyl-2,3-dihydro-1H-isoindol-2-yl)propan-1-ol (5c) gave
1-phenyl-1,3,4,5,6,7-hexa-hydro-2,6-benzoxazonine-6-carbonitrile (6c). The
analogous 1-(4-methoxyphenyl) derivatives of both medium ring systems were also
prepared, and some mechanistic aspects of the results are discussed. Conversion
of (6a) into the analgesic, Nefopam,is described.
The extraction of cobalt(II) from lithium chloride solutions by aliquat 336R dissolved in chloroform
Authors: Paimin R , Cattrall RW
Published: September 2010

The extraction of
cobalt(II) by Aliquat 336R from 7 M
lithium chloride solutions involves two species from the aqueous phase, COCl42
and CoCl3-, with the former being the predominant one.
The equilibrium constants for the formation of the extracted complexes (R3MeN+)2
CoCl42- and R3MeN+CoCI3-
are: logKll 5.01 and logK12
9.55. From the results of
experiments by means of the single-drop technique, a mechanism is proposed
based on the formation of interfacial complexes by fast ion-exchange with a
rate-determining step which involves the replacement at the interface of the
complex (R3MeN+)2 COCl42-
by two molar proportions of reagent from the bulk organic phase.
Alkaloids of Hovea linearis R.Br. The isolation of Ormosia group alkaloids
Authors: Lamberton JA , Morton TC , Suares H
Published: September 2010

(+)-Sparteine, (–)-N-methylcytisine, (–)-anagyrine,
(–)-baptifoline, (±)-piptanthine
and (–)-16-epiormosanine have been isolated as alkaloids of H. linearis
R.Br. The absolute configuration of
(–)-16-epiormosanine
has been established by its formation as an hydrogenation product of the alkaloid
(–)-podopetaline. Another minor alkaloid may be a new isomer of ormosanine.
Evidence for the structure, and for a non-chair conformation in ring F of two isomeric N-formylsolasodines
Authors: Gaffield W , Benson M , Haddon WF , Lundin RE
Published: September 2010

Formylation of solasodine results in the formation of two different
3,N-diformylsolasodines whose isomerism is due to a difference in
stereochemistry at C22 rather than restricted rotation about the C=N partial
double bond of the amide or nitrogen inversion as previously proposed. Mass
spectra, 1H and I3C n.m.r. spectra have shown the isomers
to possess 22R,25R (major) and 22S,25R (minor) stereochemistry. The 22S,25R
isomer is thermodynamically preferred at elevated temperatures while the 22R,25R
isomer is kinetically favoured upon recyclization of
the ring-F opened intermediate which forms upon heating of either isomer. A
non-chair ring-F conformation is proposed for each isomer on the basis of 13C
and 1H n.m.r. spectra.
New quinolinone and bis-quinolinone alkaloids from Euxylophora paraensis
Authors: Jurd L , Benson M , Wong RY
Published: September 2010

Three quinolin-2-one
alkaloids were isolated from the heartwood of Euxylophora paraensis andidentified by spectroscopic
methods as 2,3,3-trimethyl-2,3,4,5-tetrahydrofurano[3,2-c]quinolin-4-one(2a), its N-methyl
derivative (2b), and 3-(1,2-dimethyl-2-hydroxypropyl)-4-hydroxy-1-methylquinolin-2(1 H)-one (3). Four new
dimers, E, F, G and B, were also isolated and identified as the bisquinolin-2-ones (5c), (5d), (6) and
(9). The unsaturated dimer G and an isomer have been prepared by oxidationof paraensidimerin A and C.
Preparations of 6-substituted 6H-Dibenzo[b,d]thiopyrans and their S-oxides through nucleophilic additions to 6H-dibenzo[b,d]thiopyran-6-one
Authors: Ridley DD , Smal MA
Published: September 2010

Methods for the
preparations of 6-substituted 6H-dibenzo[b,d]thiopyrans and the corresponding S-oxides were explored. The
most general procedure involved the addition of Grignard reagents to
6H-dibenzo[b,d]thiopyran-6-one, whereupon 6-substituted 6H-dibenzo[b,d]thiopyran-6-ols
were formed. The carbonyl group
in the thioester thus behaved like an isolated ketone in its reactions with nucleophiles. The resultant
dibenzothiopyran-6-ols were acid-labile, and dehydration products underwent further modification in
some instances. Oxidation of the olefins afforded stable S-oxides. The dianion formed by
reduction of dibenzothiophen also offered routes to 6-substituted 6Hdibenzo[b,d]thiopyrans, but the
reactions of this dianion were non-regioselective and thus were of limited use.
Flame ionization of iron and lead
Authors: Ham NS , McAllister T
Published: September 2010

The mass spectra of ions in
flame ionization detector (f.i.d.) type flames
containing iron and lead compounds show that, in addition to metal ions, prominent
species of formula (MoxHx+1)+ are present
which are apparently protonated metal hydroxides. For FeOH2+
and PbOH2+, however, the structure of these species may
be identical with those of metal-ion hydrates. This work confirms the presence
of Pb+ ions in flames to which lead compounds are added, but, in
general, metal or metal-containing ions should not affect the saturation
current obtainable in an f.i.d, used to detect organometallic compounds. Ionization of iron and lead and their
oxides and hydroxides by H3O+ may contribute to
atmospheric ionization in the presence of metallic pollutants.
Reduction potentials of pentaammine complexes of cobalt(III), rhodium(III) and iridium(III): physical correlations
Authors: Curtis NJ , Lawrance GA , Sargeson AM
Published: September 2010

The reduction potentials of a large range
of [M(NH3)5L]π+ complexes (M = CoIII, RhIII, IrIII)
have been determined in aqueous solution (μ 0.1 M, NaClO4).
Irreversible reductions span the range from + 0.22 to -0.47 V for cobalt(III)
complexes and from -0.86 to -1.45 V for rhodium(III),and occur near -1.7 V for
iridium(III), determined against the standard (KCl)
calomel electrode. Despite several reports to the contrary in the literature,
no correlations exist of E� with absorption spectra (Co and Rh),
nuclear magnetic resonance spectra [δ(1HN), Co, Rh, Ir, and δ (59Co)], vibrational
spectra [v(Co-N)], or rates of aquation and base
hydrolysis (Co, Rh, Ir). Complexes which undergo
outer-sphere [e.g., with Ru(NH3)62+]
and predominantly inner-sphere (e.g., with VZ+aq)
homogeneous electron transfer can be distinguished by the presence or absence
of a correlation of In kex with E�
respectively, consistent with the expectations of the Marcus-Hush theory of
outer-sphere electron transfer.
Syntheses of the two optical isomers of the insect anti-juvenile hormone agent ethyl p-[2-(t-Butylcarbonyloxy)butoxy]benzoate (ETB) and their biological activities
Authors: Horn DHS , Nearn RH , Siddall JB , Staal GB , Cerf DC
Published: September 2010

The optical isomers (9) and
(13) of the insect anti-juvenile hormone, (�)-ethyl p-[2-(t-butylcarbonyloxy)butoxy]benzoate (ETB) (14), have been synthesized and their
biological activities examined in the tobacco hornworm Manduca sexta. It was found that the observed
anti-juvenile hormone activity at low dose levels and juvenile hormone activity
at higher levels in the Manduca sexta, after
topical treatment with the racemic mixture (14) is due entirely to the (–)-enantiomer (9), the (+)-enantiomer
(13) being completely inactive.
Crystal structure of Bis(2,2':6',2''-terpyridyl)cobalt(II) iodide dihydrate at 295 K and at 120 K
Authors: Figgis BN , Kucharski ES , White AH
Published: September 2010

The crystal structure of
the title compound, [CO(C15H11N3)2]
12.2H2O, has been determined by single crystal X-ray diffraction
methods at 295 K and at 120 K, being refined by least squares to residuals of
0.051 and 0.035 respectively for 982 and 1024 'observed' reflections at these
temperatures. Both structures are based on a P42/n tetragonal cell, a c. 8.9, c c. 19.4 �, Z 2, in which only
a quarter of the cation is independent, being located about a site of 4
symmetry. At room temperature (μoff c.
3.2 BM) Co-N (central, distal) are 1.942(7), 2.104(5) � diminishing to
1.912(5), 2.083(4) � at 120 K, with μoff c. 2.2 BM,
corresponding to a fully populated low-spin ground state.
On the regioselectivity of free radical processes ; reactions of benzoyloxy, phenyl and t-butoxy radicals with some α,β-unsaturated esters
Authors: Moad G , Rizzardo E , Solomon DH
Published: September 2010

The reactions of three
electrophilic radicals, benzoyloxy, phenyl, and t-butoxy, have been examined with a series of α, β unsaturated
esters; methyl acrylate, methyl methacrylate, and methyl crotonate. For the
three monomers the ratio of hydrogen abstraction to double bond addition was
found to increase and the ratio of head against tail addition to decrease in
the series: benzoyloxy; phenyl; t-butoxy.
Relative rates for these reactions have been determined and the factors
influencing the mode of reaction are discussed.
The chemistry of pyrrolic compounds. LIII. Polyhydroxy and polyacetoxy derivatives of porphyrins
Authors: Chau DD , Clezy PS , Henderson RW , Pham H , Ravi BN
Published: September 2010

Several polyhydroxy- and
polyacetoxy-porphyrins have been prepared and their properties studied as part
of an investigation to find suitable porphyrins for use in the detection and/or
treatment of malignant tumours. Low solubility in aqueous media has so far
prevented a clear assessment of their biological properties.
A multinuclear magnetic resonance study of the tetraphenylarsonium and tetraphenylphosphonium tetraphenylborates in nonaqueous solvents
Authors: Farmer RM , Sasaki Y , Popov AI
Published: September 2010

Arsenic-75, phosphorus-31,
boron-11, carbon-13 and lH n.m.r. measurements are reported for Ph4As+,
Ph4P+ and Ph4B- ions in a number of
nonaqueous solvents. The resonance frequencies of the
first three nuclei are very nearly independent of the solvent and of the salt
concentration indicating an effective shielding of the central atom from the
solvent by the four phenyl groups. In contrast the resonance frequencies of the
ortho, meta and para carbons and
protons of the phenyl rings vary with the solvent. The resonances of the
cationic and the anionic carbons and protons are different and the differences
are solvent-dependent. The results indicate that the two cations and the anion
are solvated to a different extent and that the 'reference electrolyte' assumption,
used to obtain single ion transfer activity coefficients, has to be used
cautiously.