bluuebunny/crossref_metadata_2025 huggingface dataset:
A phosphorus-31 magnetic resonance study of ligand exchange on Hexakis[methyl methyl(phenyl)phosphinate]yttrium(III) ion and the solution chemistry of related yttrium(III) species
Authors: Pisaniello DL , Lincoln SF
Published: September 2010

A 31P n.m.r, study
shows that the species [YLn3+ where n = 4,5,6 for L = OP(NMe2), or OPPh3 n = 5,6 for L = OPMe(0Me)Ph
are the major yttrium(III) species formed with these ligands in CD2CI2
solution. A detailed ligand exchange study of the latter species shows the rate
law to be: exchange rate = 6(kl+k2[OPMe(OMe)Ph])[Y(OPMe(OMe)Ph)63+] where k1(215 K) = 312�13 s-1,
ΔH1‡ = 3l·4 � 1.4 kJmol-1, ΔS1‡
= -48·4�6.6 J K-1 mol-1, k2(215 K) = 455
� 31 dm3 mol-1 s-1, ΔH2‡ = 35·2�2.8
kJmol-1 and ΔS2‡ = -27·6 � 12·7 JK-1
mol-1, where the k1
and k2 terms are assigned
to D and A mechanisms respectively. The rate of OP(OMe)3
and OPMe(OMe)2
exchange on yttrium(III) is found to be in the fast exchange limit of the
n.m.r. time scale and thus the coordination numbers of the yttrium(III) species
formed with these ligands are not directly determined in solution.
Qualitatively it appears that the coordination number and the lability of the yttrium(III) species increases as the size
of the ligand decreases. The isolation of the crystalline species [Y(OP(NMe2)3)5ClO4](ClO4)2,
[Y(OPPh3)4](ClO4)3, [Y(OPMe(OMe)Ph)6] (ClO4)3,
[Y(OP(OMe)3)6](ClO4)3
and [Y(OPMe(OMe)2)6](ClO4)3
is reported.
Sporidesmins. XVIII. The Infrared Solution Spectra (4000-1600 cm-1) of Sporidesmin, Sporidesmin-B, Sporidesmin-D and Sporidesmin-E
Authors: Ronaldson J
Published: September 2010

The solution infrared
spectra of sporidesmin, sporidesmin-B, sporidesmin-D and sporidesmin-E have
been determined in carbon tetrachloride. Though these compounds differ only
slightly in structure, their spectra show marked differences which indicate
differences in the intramolecular hydrogen bonding. These differences have been
related to the known structures by using molecular models. ��� In the v(OH) region, the spectra for
sporidesmin-B and sporidesmin-E are similar, though the former compound has
only one hydroxy group and the latter an epitrithio group. The spectrum for
sporidesmin-D reflects the relaxation of the strain arising from the disulfide
bridge in sporidesmin. ��� The non-bonded carbonyls absorb at
1685-1718 cm-1 and the corresponding bonded carbonyls absorb at
1657-1680 cm-1. The Δv(C0) was
greatest in sporidesmin-E. ��� In the C-H stretching region, the spectra
are similar except for sporidesmin-D where there are the extra absorptions for
the two S- methyls. ��� The instability of sporidesmin-E is
discussed.
Studies on intramolecular alkylation. XIV. The preparation of methoxylated cyclohexadienone derivatives from intramolecular diazoketone cyclizations inrelationship to isoquinoline alkaloid synthesis
Authors: Johnson DW , Mander LN , Masters TJ
Published: September 2010

A series of di- and tri-methoxytetrahydronaphthyl
diazomethyl ketones (4), (6), (8), (25) and (27) have been prepared and
cyclized in trifluoroacetic acid. A wide range of methoxylated cyclohexa-
dienone containing tricyclic compounds (12), (15), (17), (18) and (30) were
obtained as well as several rearranged derivatives, i.e. (13), (14), (32) and
(33).
Chemistry of the Podocarpaceae. LVII. The preparation of some 1,3-Dioxans with ambergris-type odours
Authors: Cambie RC , Palmer BD
Published: September 2010

The preparation of a series
of five-, six-, seven- and eight-membered ring dioxa compounds is described.
All possess odours of the ambra-type, the ambergris character decreasing in
intensity as the size of the dioxa ring is increased. The formation of some
methoxymethyl ethers is described.
Derivatives of Bicyclo[2,2,2]octane-2,6:3,5-dicarbolactone
Authors: Carman RM , Smith SS
Published: September 2010

The reactions of the title
dilactone with both acid and base are discussed. Evidence is presented for
stable γ-lactones in the bicyclo[2,2,2]octane-2,6-carbolactone series.
Epimerization α to hindered acid groups occurs under acetylating conditions to
relieve steric strain in this system.
A preliminary study of the influence of alkali-metal promoters on the selectivity and activity of vanadium catalysts in the oxidation of naphthalene
Authors: Foster NR , Wainwright MS , Westerman DWB
Published: September 2010

The oxidation of
naphthalene over vanadia catalysts promoted by alkali- metal sulfates was
studied in the temperature range 400-440°C. The effects of SO3 levels
and alkali-metal sulfate promoter type on catalyst activity and selectivity
were investigated in laboratory fixed-bed reactors employing integral
conversions. ��� The relative promoting abilities of the
alkali metals sodium, potassium, rubidium and caesium were investigated with
laboratory catalyst preparations. Alkali metals of higher atomic number
favoured selectivity to partial oxidation products with an associated loss in
overall activity.
Effects of p-substituents on the conformation of acetophenone
Authors: Mirarchi D , Ritchie GLD
Published: September 2010

Experimental dipole moments
and infinite-dilution molar Kerr constants are reported for six p-substituted
acetophenones (CH3COC6H4X; X = Me, But,
NO2, CN, F, Br) as solutes in carbon tetrachloride at 298 K.
Analysis of these results and reconsideration of previously reported data for
acetophenone and p-chloroacetophenone yields the dihedral angle, Φ, between the planes of the carbonyl and aryl groups
in the effective conformation of each molecule (X = H, Φ = 0°; Me, 0°; But, 10�10°; NO2,
20�15°; NO2, 20�20°; F, 27�5°; Cl, 32�5°;
Br, 30�10°).
Reactions of trifluoromethyl radicals. VI. Hydrogen abstraction from trifluoroacetic acid and trifluoroacetic (2H1)acid
Authors: Arthur NL , David LF
Published: September 2010

The hydrogen abstraction
reactions of CF3 radicals with CF3COOH and CF3COOD
CF3 + CF3COOH
→ CF3H + CF3COO ����������������(1)CF3 + CF3COOD
→ CF3D + CF3COO ����������������(2)
have been studied in the
temperature ranges 102-225°C and 153-275°C respectively. The rate constants,
based on the value of 1013.36 cm3 mol-1 s-1
for the recombination of CF3 radicals, are given by (k in cm3
mol-1 s-1 and E in J
mol-1):
logk1 =
(10.17�0.12)-(33140�970)/19.145T��������������������� logk2 =
(9.51�0.11)-(46090�1010)/19.145T
Quinones and quinone methides. IX. Oxidation of 2,4-Bis(1,1-dimethylethyl)-6-(4-methoxyphenylmethyl)phenol in alcoholic solvents: Monomeric products and the crystal structure of an unusual dimes, 2-[3,5-Bis(1,1-dimethylethyl)-2-{methoxy-(4-methoxyphenyl)methoxy} phenoxyl-1,5-bis(1,1-dimethylethyl)-3-[methoxy-(4-methoxyphenyl)methyl]benzene
Authors: Jurd L , Wong RY
Published: September 2010

Oxidation of the title
benzylphenol (1) with silver oxide in alcoholic media forms benzylic ethers of
type (5) in high yields; e.g. oxidation in methanol yields 2,4-bis(1,1-dimethylethyl)-6-[methoxy(4-
methoxyphenyl)methyl]phenol(5a) together with an unusual dimer, the structure
of which was shown by X-ray crystallographic analysis to be 2-[3,5-bis(1,1-dimethylethyl)-2-{methoxy(4-methoxyphenyl)-
methoxy}phenoxy]-1,5-bis(1,1-dimethylethy)-3-[methoxy(4- methoxyphenyl)methyl]benzene
(6). The benzylic ethers (5) are convenient intermediates for the syntheses of
a variety of compounds related to (1).
Generalized van der Waals theory. V. Equation of state of two-dimensional simple fluid
Authors: Hooper MA , Nordholm S
Published: September 2010

We have investigated the
two-dimensional gas-liquid condensation of a LJ(12-6) system with relevance to
monolayer adsorption. A recently developed generalized van der
Waals theory has been used to calculate critical
parameters, coexistence curves, vapour pressure curves and other thermodynamic
information partially as an investigation into the validity of the theory. Two
aspects are of particular concern. Firstly, we are interested in the
temperature and density dependence of the excluded volume effect. The effective
hard-disc diameter is determined variationally so as to minimize the free
energy. Secondly, we apply a simple means of quantizing the theory to estimate
shifts in the thermodynamic properties of light fluids due to the quantum
character of the translational motion. Apparently useful accuracy is obtained.
Magnetic anisotropies and relative aromaticities of pyrrole, pyrazole, imidazole and their N-methyl derivatives
Authors: Calder KE , Calvert RL , Lukins PB , Ritchie GLD
Published: September 2010

Experimental dipole
moments, molar Kerr constants and molar Cotton-Mouton constants at 298 K and
633 nm are reported for pyrrole, pyrazole, imidazole and their N-methyl
derivatives as solutes in dioxan. Analysis of the Kerr-effect data yields the
effective polarizability anisotropies which are used to evaluate the molecular
magnetic anisotropies from the Cotton-Mouton constants. The magnetic criterion
of aromaticity is applied by estimating for each molecule the non-local
contribution to the out-of-plane component of the magnetizability and the
magnetic anisotropy. Electron delocalization in these molecules is
significantly less than that exhibited by benzene: pyrrole and N-methylpyrrole, c. 70%; pyrazole and N-methylpyrazole, c.
65%; imidazole and N-methyl-imidazole, c. 60%. Approximately one-third of the
observed magnetic anisotropy arises from localized contributions.
The nitration of pivalophenone
Authors: Barker SD , Norris RK , Randles D
Published: September 2010

The nitration of
pivalophenone (2,2-dimethyl-1-phenylpropan-1-one), which is the first reported
electrophilic substitution on that substrate, gives o-, m- and
p-nitropivalophenones in the percentage ratio 30:44:26. This anomalous product
distribution, which differs significantly from that found for benzene rings
bearing other dipolar deactivating substituents such as acetyl groups, is
attributed to a sterically induced non-coplanarity of the carbonyl group, in
the pivaloyl moiety, with the benzene ring.
Structure odour studies with some diterpene derived acetals
Authors: Grant PK , Rowan DD
Published: September 2010

Acetals (1) and (2), analogous to the valued perfumery acetals (3) and (4), have been synthesized from manool (5) for structure/odour
comparison. Selenoxide elimination gave diene (13)
which underwent Cope rearrangement and selective epoxidation to give the 8β,9β-epoxide
(19). Borontrifluoride-catalysed rearrangement
established this stereochemistry and led by selective oxymercuration
of diene (24) to the required acetals.
Epoxidation with triphenylphosphine and diethyl azodicarboxylate. II. Methyl 4,6-O-benzylidene-D-aldohexopyranosides
Authors: Guthrie RD , Jenkins ID
Published: September 2010

Epoxidation of the
conformationally rigid diaxial diol methyl
4,6-O-benzylidene-α-D-altropyranoside with triphenylphosphine and diethyl
azodicarboxylate proceeds in high yield under very mild conditions to give
the corresponding 2,3-anhydro-D-mannoside. By contrast, the corresponding
diequatorial diol, methyl 4,6-0-benzylidene-α-D-glucopyranoside, undergoes
epoxidation only under forcing conditions and gives the D-allo isomer. Evidence
is presented for the formation of a cyclic phosphorane intermediate in the
latter case.
2'-O-Methyltenuiorin, 2''-O-methyltenuiorin and 2',2''-Di-O-methyltenuiorin. Three new tridepsides from the lichen Pseudocyphellaria faveolata
Authors: Elix JA , Lajide L
Published: September 2010

The tridepsides
2'-O-methyltenuiorin, 2''-O-methyltenuiorin and 2',2''-di-O-methyltenuiorin have been isolated
from the lichen Pseudocyphellaria faveolata in
addition to the well known compounds
tenuiorin, physciosporin and stictic acid. The structure of the new compounds followed
from the spectroscopic data and was confirmed by total synthesis.
Structural and spectroscopic studies of transition metal nitrite complexes. III. Crystal structures and spectra of Aquabis(meso-1,2-diphenylethane-1,2-diamine)-nitronickel(II) perchlorate and Bis(meso-1,2-diphenylethane-1,2-diamine)-(nitrito-O,O')nickel(II) chloride
Authors: Finney AJ , Hitchman MA , Raston CL , Rowbottom GL , White AH
Published: September 2010

The crystal and molecular structures of
the complexes [Ni(mstien),(NO2)(H2O)] ClO4
and [Ni(mstien)2(O2N)] Cl are reported (mstien = meso-stilbenediamine,
1,2-diphenylethane-1,2-di-amine). Both compounds contain nickel(II) in an
essentially octahedral ligand environment. In the latter complex, the nitrite
ion chelates, while in the former it is present as a nitro group situated trans
to a coordinated water molecule. In both complexes the conformations observed
for the amine chelate rings can be rationalized on the basis that they minimize
intramolecular ligand repulsions. The complex [Ni(mstien)2(O2N)]
NO2 is isomorphous with the analogous chloride compound, and
spectral evidence suggests that the complex [Ni(mstien)2(O2N)]
ClO4 also contains a chelating nitrite group. The electronic spectra
of single crystals of [Ni(mstien),(O2N)] X (X = Cl- and
NO2-) show bands centred at c. 25000 cm-l
which exhibit vibrational fine structure. The energies of the progressional
spacings are c.600cm-l, which suggests that the bands are probably
due to n → π* internal nitrite transitions. The band
centred at c. 20500 cm-1 in [Ni(mstien)2(NO2)(H2O)]
ClO4 also shows well resolved vibrational fine structure with a progressional
spacing of c. 630 cm-1. This implies that the band is not due to a
'd-d' transition, but must be caused by the excitation of an electron into the
nitrite π* orbital, either from a
non-bonding nitrite orbital, or more probably from the nickel ion.
Structural and spectroscopic studies of transition metal nitrite complexes. V. Crystal structures and spectra of trans-Tetrakis(pyridine)dinitritonickel(II)-pyridine (1/2), trans-Tetrakis(4-methylpyridine)dinitritonickel(II) and trans-Tetrakis(pyrazole)-dinitritonickel(II)
Authors: Finney AJ , Hitchman MA , Raston CL , Rowbottom GL , Skelton BW , White AH
Published: September 2010

The crystal and molecular
structures of the compounds [Ni(py)4(ONO)2],2py,
[Ni(γmpy),(ONO)2] and [Ni(prz)4(ONO)2]
are reported.�All three are trans nitrito complexes, the pyridine
(py) compound containing two pyridine molecules of solvation. The aromatic rings
in the first two complexes adopt 'paddle wheel' conformations with pitch angles
varying between 40 and 70�. The nitrite ions are positioned so as to minimize
repulsive interactions with the amines, and it seems likely that these groups
bond through oxygen rather than nitrogen because this allows a lesser degree of
interligand steric interference. The amine rings in [Ni(prz)4(ONO)2]
are orthogonal to the plane containing the nickel and coordinated pyrazole
nitrogen atoms; the nitrito groups are disordered between two inequivalent
positions, each of which involves hydrogen bonding with the pyrazole NH groups.
The nitrite infrared frequencies are similar to those observed for other
nickel(II) nitrito complexes except that the antisymmetric NO stretching mode
of one of the groups in the pyrazole complex is much lower in energy than
expected, being in the range normally associated with a nitrogen-bonded or
chelated nitrite group. It is suggested that this deviation may be caused by
the hydrogen bonding in the complex. The electronic spectra of the compounds
yield 10Dq values of 9100 and 8500 cm-1 for the nitrite ligands in
[Ni(py)4(ONO)2] and Ni(prz)4(ONO)2],
respectively, placing the nitrito group towards the weaker end of the spectro-chemical
series.
The synthesis of 2-Acetamido-2-deoxy-5-thio-D-glucopyranose and its derivatives
Authors: Guthrie RD , O'Shea K
Published: September 2010

Syntheses of the title
compounds are described (see Scheme 1). They proceed via the intermediate (11)
designed to facilitate the synthesis of other thiopyranose
analogues of amino sugars, particularly those of biochemical significance.
The viscosity of dilute aqueous nonelectrolyte solutions
Authors: Alexander DM , Moy DC
Published: September 2010

An equation is proposed to
describe the viscosity B coefficients
for dilute solutions of nonelectrolytes in water. It
is based on an empirical equation developed for nonaqueous
mixtures and an assumption that the entropy change on solution of the liquid solute
affects the viscosity of the aqueous system in the same way as a change of
molar entropy affects the viscosity of pure water. The equation is shown to
represent experimental results well and is especially successful in
representing the temperature dependence of the B coefficient for aqueous solutions of alcohols.
The effect of ring size in N-benzoyl saturated heterocyclic amides
Authors: Fong CW , Grant HG
Published: September 2010

The structures of the N-benzoyl
derivatives of aziridine, azetidine,
pyrrolidine, piperidine, hexamethyleneimine and heptamethyleneimine
in solution have been investigated by 13C n.m.r. spectroscopy. In
conjunction with literature crystal structure and dynamic intramolecular
exchange data, it has been concluded that N-benzoylaziridine and N-benzoylazetidine possess pyrimidal
nitrogen atoms in solution. The N-benzoyl derivatives of pyrrolidine,
�piperidine, hexamethyleneimine and heptamethyleneimine
have planar or near planar nitrogen atoms.
Chemistry of the Coccoidea. VIII. Synthesis of the ancient dyestuff kermesic acid and of related anthraquinones
Authors: Cameron DW , Deutscher DJ , Feutrill GI , Griffiths PG
Published: September 2010

The insect anthraquinones kermesic acid (3) and laccaic
acid D (2) have been synthesized efficiently, as have the plant anthraquinones aloesaponarin-I (4) and -11 (33). The syntheses were based
on regiospecific Diels-Alder addition of the silyloxy dienes (10) and (11) to
simpler quinones. Regiospecificity
was controlled by 2(3)-chloro groups in the dienophiles or, for addition to
certain naphthoquinones, by a hydroxy group peri to carbonyl.
Conformational dynamics of three substituted decahydronaphthalenes
Authors: Blunt JW , Coxon JM , Gibson JR
Published: September 2010

The thermodynamic
parameters for equilibrium of the chair-chair conformational enantiomorphs of 8a-methyl-cis-decahydronaphthalen-4a-yl acetate, Ea 67.1 � 3 kJ
mol-1, ΔH‡ 64.5 � 3 kJ mol-1,4a-chloro-8a-methyl-cis-decahydronaphthalene, Ea
73.6 � 2.5 kJ mol-1, ΔH‡ 70.8 � 2.5 kJ mol-1 and the chair-chair
conformers of (1α,4aα,8aα)-4a-methyldecahydronaphthalene-1,8a-diyl
diacetate:conformer (A) to (B) Ea
68.9 � 4 kJ mol-1, ΔH‡ 66.7 � 4 kJ mol-1, and
conformer (B) to (A) Ea 66.8 � 4 kJ mol-1, ΔH‡ 64.5
� 4 kJ mol-1 have been determined from 13C n.m.r.
studies.
Apparent molar volumes for dilute solutions of NaClO4 and [Co(en)3] (ClO4)3 in D2O and H2O at 278-318 K
Authors: Bottomley GA , Glossop LG
Published: September 2010

Apparent molar volumes for
dilute solutions of NaClO4 and [Co(en)3] (ClO4)3
in D2O and H2O were measured by using a dilatometry
technique at 278, 298 and 318 K. Comparison of limiting slopes with the
Debye-Huckel predictions from the dielectric constant and compressibility of H2O
and D2O is complicated by ion pairing. The apparent molar volumes
for NaClO4 were less in D2O than in H2O. The
complex [Co(en)3] (ClO4)3 when studied in D2O
had its amine protons exchanged by deuterium; this did not allow a direct comparison
of the apparent molar volumes of the protonated complex in each solvent system,
but revealed a large isotope effect. The apparent molar volumes of the [Co(en)3]
(ClO4)3 showed a much larger temperature dependence than
that of NaClO4.
Three new diterpenes from a soft coral Nephthea species
Authors: Poet SE , Ravi BN
Published: September 2010

Two new cembranoid
diterpenes and a non-cembranoid diterpene
have been isolated from a soft coral Nephthea species along with two previously reported
diterpenes (1) and (9). The structures were determined from spectral data and
chemical degradation sequences. The compounds were identified as (1E,3E,7E,11E,13S)-cembra-1,3,7,1l-tetraen-13-ol (6), (lE,3E,7E,llE,13S)-cembra-
1,3,7,11-tetraen-13-yl acetate (7) and
2-[(2'R*,4a'S*,8a'R*)-4a',8'-dimethyl-l',2',3',4,4a',5',6',8a'-
octahydronaphthalen-2'-yl]-5,6-epoxy-6-methyhept-1-ene(8).
Study of internal motions through N.Q.R. in 6-Chloropyridin-2-ol
Authors: Basavaraju SP , Devaraj N , Indumathy A , Sridharan KR , Ramakrishna J
Published: September 2010

Chlorine-35 n.q.r, has been observed for the first time in
6-chloropyridin-2-ol and its temperature dependence has been studied from 77 K
to room temperature. The torsional frequencies and
their temperature dependences have been calculated by using Bayer's theory with
and without Tatsuzaki's modification.
Tungsten carbonyl complexes with dithiocarbamate ligands
Authors: Broomhead JA , Young CG
Published: September 2010

The orange seven-coordinate complexes W(S2CNR2)2(CO)3
(R = Me, Et) have been prepared by the reaction of WBr2(CO)4
and NaS2CNR2.�The tricarbonyl complexes were converted into the coordinatively unsaturated complexes W(S2CNR2)2(CO)2
by reflux in methanol. The compounds provide a new route into carbonyl dithiocarbamato complexes of tungsten and their reactions
with various N- and
P-donor ligands have given the new
complexes W(S2CNR2)2(CO)2L (R = Me,Et; L = NH2NHMe, NH2NMe2,
NH3, NH2NHCOPh, C5H5N, NH2NHSO2C6H4Me,
PPh3) and bridged species [W(S2CNR2)2(CO)2]2-.μ-B
(B = N2H4, NH2CH2CH2NH2).
The synthesis and the 1H n.m.r, and infrared spectra of the
compounds are presented and discussed. The electronic spectra of W(S2CNR2)2(CO)3
and W(S2CNR2)2(CO)2 are also reported.
An improved approach to benzene annelation: the synthesis of 11-substituted octahydro-1,4:9,10-dimethanoanthracenes and a study of OH…p bonding in these systems
Authors: Paddon-Row MN , Patney HK , Pasupuleti LN
Published: September 2010

A procedure
for benzene annelation, which incorporates the best
features of previously reported techniques, is described and is applied to the
synthesis of a series of 11-substituted octahydro-1,4:9,10-dimethanoanthracenes (1a-e). Thus addition of 1,2,3,4-tetrachloro-5,5-dimethoxycyclopentadiene(7)
to (1β,4β, 4aα, 5α, 8α, 8aα)-anti-9-acetoxy-1,2,3,4,4a,5,8,8a-octahydro-1,4:5,8-dimethanonaphthalene(4b)
gave the adduct (8b).* Deacetalization of (8b)
followed by thermal, cheletropic loss of CO and
subsequent base-induced dehydrochlorination gave the 5,6,8-trichlorooctahydro-1,4:9,10-dimethanoanthracen-anti-11-ol (17b) which could
easily be converted into (1c) by using sodium and ethanol. Infrared and 1H
n.m.r. studies revealed the presence of a strong intramolecular OH…π bond in the syn-alcohol (1e). The observation of an unusually large
vicinal coupling constant, J(HCOH) 12
Hz, for (1e) implies that the H-C-O-H exists in the antiperiplanar
conformation which also maximizes the strength of the OH…π bond.
Bisphenol flukicides. VI. The crystal and molecular structures of 2,2'-(Phenoxymethylene)bis(4-chloro-6-nitrophenol) and a triethylamine adduct of 2,2'-(Benzyloxymethylene)bis(4-chloro-6-nitrophenol)
Authors: Hay DG , Mackay MF
Published: September 2010

X-ray crystallographic
analyses have defined the conformational detail in the title compounds.
Crystals of 2,2'-(phenoxymethylene)bis(4-chloro-6-nitrophenol)
(1), Cl9H12Cl2N2O7, are
monoclinic: space group P21/n, a
8.616(1), b 16.214(1), c l3.727(1) �, β 92.13(1)� and Z 4.
The triethylamine adduct of 2,2'-(benzyloxymethylene)bis(4-chloro-6-nitrophenol)
(2),Et3N, C20H14Cl2N2O7,C6H15N,
crystallizes in the monoclinic space group P21/c with a 9.454(1), b 11.911(2), c 25.392(2) �,
ββ 109.96(1)� and Z 4. The structures were
refined with diffractometer data measured with Cu Kα
radiation to R 0.061 (1761 terms) for (1) and R 0.063 (1230 terms) for (2),Et3N.
The methylenebisphenol moieties in the molecules of
(1) and (2) adopt twist and butterfly conformations respectively. In (1), the
dihedral angles between the perpendiculars to the plane of the C-C-C bridge and
the phenol rings are 61.1(4) and 71.6(4)�; in (2), these angles have values of
88.0(8) and 85.6(7)�.
Molten potassium pyrosulfate: Reactions of metals
Authors: Ford AN , Meehan BJ , Tariq SA
Published: September 2010

The reactions of the fist
row transition metals and zinc with molten potassium pyrosulfate were
investigated. It was found that Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn were
oxidized to TiIV, VIV, CrIII, MnII,
FeIII, CoII, NiII, CuII and Zn11
respectively and the reaction products of the pyrosulfate melt consisted of
sulfate and sulfur dioxide. The stoichiometries of these reactions have been
established.
Preparation of arenesulfinic esters of 1,2:5,6-Di-O-cyclohexylidene-α-D-glucofuranose, and their conversion into optically active sulfoxides
Authors: Ridley DD , Smal MA
Published: September 2010

Arenesulfinyl chlorides react readily with 1,2:5,6-di-O-cyclohexylidene-α-D-glucofuranose
in the presence of pyridine to afford the corresponding arenesulfinates.
The ratio of diastereoisomeric sulfinates
formed exceeds 2 : 1 with the major diastereoisomer
possessing the (R)-configuration at sulfur. The diastereoisomeric
esters are oils and were separable only in the case of the mesityl
derivative when the crystalline, optically pure (R)-mesitylenesulfinic
ester was isolated. Treatment of the diastereoisomeric
sulfinates with Grignard
reagents gives optically active sulfoxides in enantiomeric excess corresponding to the diastereoisomeric excess in the esters. Careful recrystallization of these optically impure sulfoxides leads to optically enriched products in favourable cases.
Studies of Australian soft corals. XXVII. Two novel diterpenes from Sarcophyton glaucum
Authors: Bowden BF , Coll JC , Willis RH
Published: September 2010

The soft coral Sarcophyton
glaucum is shown to contain
two cembranoid diterpenes (1) (1Z,5S,9E,11E)-5,9-dimethyl-12-isopropyl-6-oxocyclotetradeca-1,9,11-triene-1,5-carbolactone,
and its related
6R-hydroxy derivative (2).
The broad structural features were deduced spectroscopically and confirmed by
chemical conversion and degradation. Stereochemistry was elucidated by
comparison with the known diterpene emblide (3) also reported from S. glaucum.
Triterpenes from the lichen genus Physcia
Authors: Elix JA , Whitton AA , Jones AJ
Published: September 2010

The triterpenes 20α-acetoxyhopane-6α, 22-diol, 16β-acetoxyhopane-6α,22-diol,
6α-acetoxyhopane-16β,22-diol
and 6α,l6β -diacetoxyhopan-22-ol have
been isolated from chemical strains of Physcia aipolia. The structure of these triterpenes
followed primarily from the 13C n.m.r. spectra.
Cluster chemistry. V. Reactions between [Ru3(CO)11(CNBut)] and [Pt(η-C2H4)(PPh3)2] and related chemistry : Crystal and molecular structures of Di-μ-carbonyl-[μ-carbonyl-bis {(triphenylphosphine)platinum}]dicarbonyl(triphenylphosphine)ruthenium(2Ru-Pt)(Pt-Pt), [RuPt2(CO)5(PPh3)3], and its benzene solvate
Authors: Bruce MI , Matisons JG , Skelton BW , White AH
Published: September 2010

The reaction between [Ru3(CO)11(CNBut)] and [Pt(η-C2H4)(PPh3)2] at -30° affords a thermally
unstable intermediate complex (A), which decomposes at room temperature affording, inter alia,
[Ru2Pt(CO)7(PPhd3)3 (1), [RuPt2(CO)5(PPh3)3] (2), [RuPt2(CO)6(CNBut)(PPh3)] (5) and [Ru2Pt2-
(CO)9(CNBut)(PPh3)] (6). The hexanuclear complexes [Ru2Pt4(CO)5-n(CNBut)(PPh3)4+n] [n = 0
(17) and 1 (18)] are obtained, with [Ru2Pt(CO)5(CNBut)(PPh3)4] (16), from reactions at 80°.
Related Ru2Pt and RuPt, complexes are obtained from reactions between complex (A) and CO,
CNBut, Pme3, P(C6H4Me-p)3, or P(OMe)3; related reactions between [Ru3(CO)11(CNBut)] and
[Pt{P(C6H4Me-p)3}4], and between [Ru3(CO)10(CNBut)2] and [Pt(η-C2H4)(PPh3)2, are also
described.
The crystal structure of [RuPt2(CO)5(PPh3)3] has been determined by single-crystal X-ray
diffraction methods at 295(1) K and refined by least squares to a residual of 0.035 for 6774
'observed' reflections. Crystals are triclinic, P 1, a 15.893(5), b 15.400(5), c 12.651(4) Ǻ, α 57.04(2),
β 77.09(3), γ 84.10(3)°, Z 2. Crystals of the dibenzene solvate of the complex are monoclinic,
P 21/c, a 11.868(4), b 18.647(8), c 29.24(1) A, β 98.35(3)°, Z 4, the structure being refined to a
residual of 0.057 for 4530 'observed' reflections. Ligand dispositions are compared in detail with
those observed in the analogous compound previously described with the methyldiphenylphosphine
Iigand.
Low-temperature laser Raman spectroscopy of synthetic carbonated apatites and dental enamel
Authors: Nelson DGA , Williamson BE
Published: September 2010

A range of synthetic carbonated apatites and human dental enamel have been studied at low temperatures
(50 K) by laser Raman spectroscopy. The widths of the Raman spectral bands of hydroxyapatite
were significantly reduced at low temperatures with the appearance of several peaks unobserved
at room temperatures. The number of observed phosphate and hydroxyl ion Raman peaks
was consistent with the space group P63. Spectra of carbonated apatites were not further resolved
at low temperatures and Raman peak broadening due to loss of long-range translational order in
the apatite structure was linearly correlated with the carbonate content of the sample. The same
Raman peak broadening occurred in the spectrum of dental enamel. The number of carbonate bands
in the Raman spectrum of carbonated apatites indicated that carbonate exists in two crystallographically
distinct sites of different symmetry within the apatite structure.
The application of the Hammett equation to 13C N.M.R. spectrometry. V. The transmission of electronic effects through azophenylene and ethenylphenylene groups
Authors: Christoforou D , Happer DAR
Published: September 2010

The 13C n.m.r. spectra of a number of ethyl (3-aryl)azo-, (4-aryl)azo-,
2-(4-arylethenyl)-cinnamates have been measured in
CDCl3. Comparison of the data with those for the corresponding ethyl
3-arylpropenoates has been used to investigate the attenuation of electronic
effects by the 3- and 4-azophenylene and the 4-ethenylphenylene linkages.
The structure determination of two related eremophilone dimers
Authors: Lewis DE , Massy-Westropp RA , Ingham CF , Wells RJ
Published: September 2010

The first representatives
of a new class of eremophilone dimers
have been isolated from the wood oil of Eremophila mitchelli and shown by a combination of spectroscopic
and X-ray techniques to possess the unusual
1-(8',8'a-dimethylperhydronaphthalen-2'-yl)-1,4,5,10a-tetramethylperhydroanthracene
carbon skeleton. These two natural products are the first C30
compounds to be isolated from any member of the genus Eremophila.
Site lifetime temperature variations in intermolecular exchange processes characterized by a two-term rate law
Authors: Pisaniello DL , Lincoln SF , Kurucsev T
Published: September 2010

The temperature dependence
of the site lifetimes, tA and
tB, characterizing the intermolecular exchange
of X between sites A and B through simultaneous first-order and second-order
processes as expressed in the rate law
1/tA = XB/XAtB =
k1 + k2[B]
and the treatment of such
data determined by nuclear magnetic resonance spectroscopy are discussed.
Multinuclear N.M.R. study of some di- and tri-methylplatinum(IV) complexes
Authors: Agnew NH , Appleton TG , Hall JR
Published: September 2010

The 13C n.m.r. spectrum of the dimer [PtMe2Br(MeOH)(p-OH)]2, formed by dissolving the complex
[PtMe2Br(OH)]n in methanol, has been analysed, to give 2JPt-O-Pt 103.6 HZ. 1H and 1H-decoupled
195Pt spectra show complex patterns owing to superposition of spectra from different isotopomers.
By contrast, solutions of [PtMe2Br2]n in methanol, which contain monomeric PtMe2Br2(MeOH)2,
give simple spectra.
[PtMe2Br(OH)]n dissolves in dilute aqueous KOH solution at pH 9 to give a solution containing
the 'inert' dimer [PtMe2Br(OH)(μ-OH)]22-. Other species are present at higher pH, but the solution
never contains simple PtMe2Br(OH)32- alone. Dissolution of [PtMe2(OH)2(H2O)1.5]. in alkali at
pH 12 gives a dimer [PtMe2Br(OH)(μ-OH)]22- whose 13C n.m.r, spectrum has been analysed to
give 2JPt-O-Pt 123 .5 HZ.
Progressive substitution of water in fac-PtMe3(H2O)3+ by pyridine causes regular 195Pt shifts
to lower frequency. 195Pt, 13C and 1H data indicate that fac-PtMe3X32- exist as simple anions for
X = NO2, CN, but not for X = NCS.
195Pt chemical shifts of di- and tri-methylplatinum(IV) complexes are discussed. The hydroxobridged
dimers resonate at higher frequencies than monomeric complexes, owing to strain in the
four-membered Pt(OH)2Pt rings. is much more sensitive to the cis influence than 2JPt-CH3.
Surface properties of Fe2O3-SiO2 mixed oxide and the activity for but-1-ene reaction
Authors: Iizuka T , Tatsumi H , Tanabe K
Published: September 2010

The oxidative dehydrogenation
and isomerization of but-1-ene were studied over Fe2O3-SiO2
catalysts of different composition. It was observed that the activity and
selectivity to buta-1,3-diene increased markedly on adding a small amount of
SiO2 to Fe2O3. To examine the activity and the
mechanism of these reactions, an experiment with deuterium isotope tracer, as
well as an infrared study, was carried out. On the basis of the results, it was
concluded that the ally1 intermediate mechanism was operative for but-1-ene
isomerization and buta-1,3-diene formation over Fe2O3-rich
catalysts, and the carbenium ion mechanism was operative for but-1-ene
isomerization over SO2-rich catalysts.
Cluster chemistry. VII. Some reactions of Ru3(CO)11(CNBut) with CO or Group 5B donor ligands: a route to mono- and di-substituted derivatives of Ru3(CO)12
Authors: Bruce MI , Matisons JG , Wallis RC
Published: September 2010

The complex Ru3(CO)11(CNBut) is shown to react with CO or ligands (L)
containing P, As or Sb as donor elements, by
displacement of CO or CNBut, thus
affording a new route to complexes Ru3(CO)11L [L = CO,
PPh3, P(C6H4Me-p)3 or Pcy3] and Ru3(CO)10(CNBut)L [L = CNBut,
PPh3, P(C6H4Me-p)3, PCy3, AsPh3 or SbPh3].
Anisochrony induced by transmission of chirality across a triple bond
Authors: Morris DG , Shepherd AG , Walker MF , Jemison RW
Published: September 2010

In the substituted camphors
(2) and (3), the chiral bicyclic moiety causes anisochrony of the geminal
methyl groups from which it is separated by an ethynylic group.
Can chelation be important in the antiviral activity of isatin β-thiosemicarbazones?
Authors: Stunzi H
Published: September 2010

The stability constants of
5-sulfonatoisatin β-thiosemicarbazone (β-thiosemicarbazonoisatin-5-
sulfonate) [sibt,(3)] with Zn2+ and Fe2+ have been determined
from slow pH titrations (I 0.15M KNO3,
37�). At pH 7.4, the conditional stability constants for the sibt complexes are
logK1' 4.5 (Zn2+),
3.1 (Fe2+) and log β2' 8.9 (Zn2+), 6.5
(Fe2+). The mixed ligand complexes Zn(sibt)L (L = histidine or
glycine) have conditional stability constants log β1110' 8.8
and 7.0, respectively, at pH 7.4. Copper(I) complexes of sibt and
bishistidinato-copper(II) coexist in mixtures of Cu2+, sibt and
histidine. [In solutions of copper ions, sibt (complexes Cu+) and
histidine (chelates Cu2+), the response of the Orion
cupric-ion-selective electrode is not stoichiometric.] Also studied was
1-methyl-5-sulfonatoisatin β-thiosemicarbazone [msibt,(4)] which behaves
like sibt. 5-Sulfonatoisatin β-semicarbazone and p-sulfonatobenzaldehyde thiosemicarbazone (p-thiosemicarbazonomethyl- benzenesulfonate) are weak ligands.
Comparison of the stability constants with those of complexes of biologically
relevant chelating agents showed that isatin β-thiosemicarbazones are not
expected to form stable complexes with zinc and iron in vivo. Bidentate thiosemicarbazones, such as benzaldehyde
thiosemicarbazones, form even weaker complexes. Both classes of
thiosernicarbazones have a similar activity against vaccinia virus; this
activity seems not to depend on metal ion chelation.
Protein-water interactions in solution: The water-gelatin-electrolyte system
Authors: James DW , Rintoul L
Published: September 2010

The
interactions between water and gelatin have been studied by means of infrared
and polarized Raman spectroscopy. The variations in band position and band
intensity of the infrared vibrational band indicated
that in the gelled state water molecules were tightly bound and probably
bridged between carbonyl and amide groups. This tight bonding was broken in the
ungelled state. The relaxation parameters of the
nitrate ion were used to probe the influence of the electrolytes NaNO3
and (Me4N)NO3. For both electrolytes there was a considerable
increase in the reorientational relaxation time with
increase in gelatin concentration. This confirmed the strong binding of water to
the protein. The vibrational relaxation time in the
presence of sodium ions showed little dependence on gelatin concentration;
however, in the presence of the tetramethylammonium
ion the vibrational relaxation time decreased sharply
as the concentration of gelatin increased. This indicated that the nitrate ion
was closely associated with the water bound to the protein.
The structure of mer-bis[di(3-aminopropyl)amine]cobalt(III) perchlorate, and an energy minimization analysis of the [Co(dpt)2]3+ system
Authors: Hambley TW , Searle GH , Snow MR
Published: September 2010

X-ray crystallographic
analysis shows that the isolated [Co(dpt)2](ClO4)3
[dpt = di(3-aminopropyl)-amine]
is the mer
geometric isomer. All four six-membered chelate rings of the complex adopt flattened chair
conformations, and substantial internal strain is evident in the structure. The
crystals are monoclinic, space group P21/c, with a 15.259(3), b 10.646(2), c 15.367(3) �,
β 9935(1)�. The structure was refined by blocked-matrix least-squares
techniques to an R factor (on 1731 F)
of 0.042. A molecular mechanics study of the [Co(dpt)2]3+
system shows that the structure (geometric isomer and conformer) having the
lowest strain energy is mer-(chair,
chair, chair, chair) which is that observed in the solid state, and predicts
its coexistence in solution with several other conformers, particularly mer-(chair,
chair, chair, λ-skew) and mer-(chair, chair, δskew,
chair). The calculated isomer proportions are mer � u-fac > s-fac in accordance with the experimental
observation of the mer
only. The substantially higher strain energy of the mer isomer compared to mer-[Co(dien)2]3+ accounts for the tendency
to hydrolysis of mer-[Co(dpt)2]3+.
The identity of protomycin with the glutarimide antibiotic streptimidone
Authors: Becker AM , Rickards RW
Published: September 2010

Critical re-evaluation of
the published data, together with additional experimental evidence, establishes
that protomycin, previously suggested to have the structure (3), is identical
with the glutarimide antibiotic streptimidone (1).
Synthesis of fluoronaphthoquinones: Halide displacement by naked fluoride
Authors: Cameron DW , Feutrill GI , Griffiths PG , Richards KR
Published: September 2010

Nucleophilic displacement
of chloride or bromide from 2-halo-1,4-naphthoquinones has afforded easy
synthesis of 2-fluoronaphthoquinones. The procedure involved mild treatment
with unsolvated fluoride generated by crown polyether
complexation of potassium fluoride in acetonitrile.
Excess second virial coefficients for some dilute binary gas mixtures
Authors: Martin ML , Trengove RD , Harris KR , Dunlop PJ
Published: September 2010

Excess and interaction
second virial coefficients have been measured in the
temperature range 290-320 K for 20 binary gaseous systems. Several of these
systems have previously been studied by Brewer. The present values are in
excellent agreement with his results. The excess virial
coefficients have been used to calculate excess molar enthalpies of mixing at
300 K.
Mass spectrometric study of the vaporization of the alkali chloride-cuprous chloride systems
Authors: Williams DJ
Published: September 2010

Mass spectrometry has been
used to determine the relative ion intensities, appearance energies and
variation of ion currents with temperature, in the alkali chloride-copper(I)
chloride systems. Enthalpy data for the systems have been calculated.
The molybdenum-mercury bond. A multinuclear (1H, 13C, 31P, 95Mo and 199Hg) n.m.r. study of (η5-C5H5)(CO)2LMoHgX [L = CO, P(OMe)3 and PPh3; X = Cl, Br, I, S2COEt, S2P(OEt)2, S2CNEt2 and Mo(CO)3(η5-C5H5)] complexes and the crystal and molecular structure of (η5-C5H5)(CO)3MoHgS2CNEt2
Authors: Kubicki MM , Kergoat R , Le Gall J , Guerchais JE , Douglade J , Mercier R
Published: September 2010

The nature of the
molybdenum-mercury bond has been studied by means of i.r.
and multinuclear n.m.r. spectroscopies on complexes
of the type (η5-C5H5)(CO)2LMoHgX
[L = CO, P(OMe)3 and PPh3; X = Cl, Br, I, S2COEt, S2P(OEt)2, S2CNEt2 and Mo(CO)3(η5-C5H5)].
The results indicate the strong covalent character of the Mo-Hg bond. The
chemical shifts of 95Mo resonances were found in the range from
-1706 to -1939 ppm and those of 199Hg ones
in the range from +236 to -1107 ppm. The structure of
(η5-C5H5)(CO)3MoHgS2CNEt2
has been determined; P21/2, a
12.012(5), b 8.206(3), c 17.037(4) �, β 92.58(3)�, Z 4, R
0.045. Mo-Hg distance is 2.714(3) �.
The structure of dichloro(L-histidine)copper(II)
Authors: Colyvas K , Tietze HR , Egri SKJ
Published: September 2010

The structure of the
orthorhombic form of the title compound has been determined by X-ray crystallography.
The space group was found to be P212121
(No.19,D24 = V4) with a 10.01(5), b 5.944(6), c 17.5469(7) � and Z 4. The structure
was refined by least squares to R 0.0614. It consists of chains of molecules
with the carboxy oxygen atom, the amino nitrogen atom
and the two chlorine atoms forming an approximate square plane about the copper
atom, with two bridging chlorine atoms from two adjacent molecules completing a
distorted octahedron. Extensive hydrogen bonding links the chains together.
The correlation of regiochemistry with structure in the SRN1 reaction of aci-nitronates with p-nitrobenzylic substrates
Authors: Norris RK , Randles D
Published: September 2010

The rate and regiochemistry of the SRN1 reactions of aci-nitronates
with p-nitrobenzylic
substrates are profoundly affected by branching at the positions adjacent to
the reaction sites (Cβ). Definitive
rules which predict whether C-alkylation will occur in the association step
involving p-nitrobenzylic
radicals and aci-nitronate
ions are formulated. β-Branching causes O-alkylation or reductive processes to increase. In some cases no
recognizable product formation results. Benzylic
alcohols, p-nitrophenyl
alkyl ketones and/or their oximes, and p-nitrophenol are among the products which result from
subsequent reactions of the O-alkylation
products, aci esters of benzylic alcohols.
Synthesis of 3-Ethenyl-4-methylcyclohex-2-en-1-one from 4-methylanisole
Authors: Burge GL , Collins DJ , Reitze JD
Published: September 2010

Epoxidation of 8-methyl-1,4-dioxaspiro[4,5]dec-7-ene (13) with peroxybenzoic acid afforded
6'-methylspiro[1,3-dioxolan-2,3'-[7]oxabicyclo[4,1,0]heptane] (12), isomerization of which with a catalytic
amount of lithium perchlorate in refluxing benzene
yielded 8-methyl-1,4-dioxaspiro-[4,5]decan-7-one (15). Reaction of this with vinylmagnesium bromide gave one diastereoisomer
of 7-ethenyl-8ξ-methy1-1,4-dioxaspiro[4,5]decan-7-ol (18a) or (18b).
Attempts to dehydrate this alcohol resulted in either no reaction, or in
formation of ketonic products including
3-ethenyl-4-methyl-cyclohex-2-en-1-one (4). Mild treatment of the hydroxy vinyl acetal (18a) or (18b) with dilute sulfuric
acid in dioxan afforded crystalline
3-ethenyl-3-hydroxy-4-methylcyclohexanone (19) which when allowed to react with
dilute sulfuric acid in ethanol at room temperature gave 3-ethenyl-
4-methylcyclohex-2-en-1-one (4). The crystalline dithioacetal
(20), obtained from 3-ethenyl-3-hydroxy-4-methylcyclohexanone (19), gave a
complex mixture of products upon attempted dehydration with thionyl
chloride in pyridine.
The infrared matrix isolation spectra of carbon dioxide. I. Deuterium matrices : Identification of bands due to carbon dioxide dimers
Authors: Irvine MJ , Pullin ADE
Published: September 2010

The infrared spectra of CO2
isolated in deuterium matrices at c.6K are reported for molar ratios of D2/CO2
between 50 and 3200. The bending mode V2 of CO2 appears
as a narrow doublet in the matrix spectra. Bands due to CO2 dimers
are identified in the V2 region from their concentration dependence
and from mixed isotope spectra (12CO2and 13CO2).
No dimer bands were observed in the monomer antisymmetric
stretching region. In this respect the spectra of CO2 in D2
matrices resemble those in N2 matrices. The observed dimer spectrum
is compared with those predicted on the basis of T-shaped and staggered
parallel configurations for the dimer and is interpreted as favouring
the latter configuration. The desirability of obtaining matrix spectra at
sufficiently high resolution is stressed.
The stereochemistry of organometallic compounds. XXIII. Synthesis of a chiral diphosphinite (diphin) and evaluation of its use as a ligand for asymmetric catalysis
Authors: Jackson WR , Lovel CG
Published: September 2010

(+)-(3S,4S)-Tetrahydrofuran-3,4-diyl
bis(diphenylphosphinite) [(+)-diphin] has been synthesized and its efficiency
as a ligand in asymmetric hydrogenation, hydrocyanation and hydroformylation
compared with closely related diphosphine, diphosphinite and diphosphite
ligands.
The Woodward-Prévost reaction with 5α-Androst-7-ene
Authors: Cambie RC , Craw PA , Hughes RJ , Rutledge PS , Woodgate PD
Published: September 2010

5α-Androst-7-ene (8)
has been prepared from 3β-hydroxyandrost-5-en-17-one by a route which is
superior to the usual procedure for making steroidal 7-enes. The products from
reaction of 5α- androst-7-ene under Woodward-Prevost
conditions are 5α -androsta-7,9(11)-diene (29),5α-androsta-
7,14-diene (30), 5α-androst-8-ene-7a,11β-diol diacetate
(31) and 5α -androst-8-ene-7α,11α-diol diacetate
(32). The isolation of 5α -androsta-7,9(11)-diene and its independent
conversion into the diacetates (31) and (32) supports
a mechanism proposed by Djerassi et al. for the analogous oxidation of 5α-cholest-7-ene (1).
The thermolysis of cyclic iminium salts derived from some carbohydrate diols and N-Dichloromethylene-N,N-dimethylammonium chloride (Viehe's salt)
Authors: Copeland C , Stick RV
Published: September 2010

The
cyclic iminium salts derived from N-dichloromethylene-N,N-dimethylammonium chloride
(Viehe's salt) and a variety of acyclic, cyclic and rigid bicyclic
vicinal carbohydrate diols have
been heated. The products of such thermolysis are
chloro carbamates, formed by diaxial
ring-opening of the intermediate cyclic iminium
salts.
Lithiation of bridgehead positions in 3,6-bridged piperazine-2,5-diones
Authors: Eastwood FW , Gunawardana D , Wernert GT
Published: September 2010

2,5-Dimethyl-2,5 diazabicyclo[2,2,2]octane-3,6-dione can be lithiated at the 1,4 (bridgehead) positions with 2 equiv.
of t-butyllithium at -78� and deuterated
with D2O (Do, 11.2; Dl, 56.1 ; D2,
30.1%). With butyllithium and methyl iodide the
1,2,5-trimethyl and 1,2,4,5-tetramethyl derivatives are obtained. Treatment of
dimethyl 2,6-diaminoheptanedioate dihydrochloride
with sodium methoxide in boiling butanol
gives 6,8-diazabicyclo[3,2,2]nonane-7,9-dione in 62% yield. N-Methylation
of this compound yields 6,8-dimethyl-6,8-diazabicyclo[3,2,2]nonane-7,9-dione
which can similarly be lithiated at the 1,5
(bridgehead) positions and deuterated with D2O
(Do, 5.6; Dl, 70.8; D2, 23.6%). Lithiation with butyllithium and
reaction with methyl iodide, benzyl iodide or bromomethyl
methyl ether gives mono-and di-alkylated products at
the 1,5-positions. The ability to lithiate the
bridgehead positions in these compounds is attributed primarily to a
combination of the inductive effect of the carbonyl group and dipole stabilization
by the amide nitrogen.
Molten lithium nitrate-potassium nitrate eutectic: the reaction of chromium(II) chloride
Authors: Kerridge DH , Tariq SA
Published: September 2010

The strong reducing agent
chromium(II) chloride reacted rapidly in molten lithium nitrate-potassium
nitrate, at or above the melting point of the eutectic, initially forming a
dark-brown-black solution [probably containing chromium(III) and chromium(VI)]
and gaseous nitrogen dioxide, but at 200�C giving a green precipitate (Cr2O3)
and an orange solution of dichromate. Above 450�C, a further slow reaction
converted both compounds into a yellow solution of chromate(VI) containing
nitrite partly formed by thermal decomposition of the nitrate.