bluuebunny/crossref_metadata_2025 huggingface dataset:
NUCLEAR MAGNETIC RESONANCE MEASUREMENTS OF PROTON EXCHANGE IN ALCOHOL–WATER SYSTEMS: PART III. n-, i-, s-, AND t-C4H9OH–H2O
Authors: Paterson W. G. , Spedding H.
Published: May 2006

Measurements of exchange-broadened n.m.r. signals are analyzed by recent methods to yield proton exchange rates of the reaction [Formula: see text] where R = n-, i-, s-, and t-C4H9. The rate constants suggested are 0.95 (44°), 0.90 (42°), 0.60 (46°), and 0.25 (46°) l. mole−1 sec −1, respectively. The trend in rate constants for these four systems, and the C2H5OH–, n-C3H7OH–, and i-C3H7OH–H2O systems examined in Parts I and II (W. G. Paterson, Can. J. Chem. 41, 714, 2472 (1963)), is discussed in terms of the nature of the alkyl groups in each alcohol.
REARRANGEMENT STUDIES WITH C14: XVI. REARRANGEMENTS INDUCED BY γ -IRRADIATION OF 2-PHENYLETHYL-1-C14 BROMIDE OR 2-p-METHOXYPHENYLETHYL-1-C14 BROMIDE
Authors: Thornhill D. P. , Lee C. C.
Published: May 2006

Irradiation of 2-phenylethyl-1-C14 bromide with up to 133 million rads of Co60 γ-rays gave 2-phenylethyl-2-C14 bromide with a mean Gr of 0.30 ± 0.01. Similar studies with 2-p-methoxy-phenylethyl-1-C14 bromide resulted in 2-p-methoxyphenylethyl-2-C14 bromide with a mean Gr of 0.46 ± 0.04. Monomeric, liquid organic products were found to be benzene, ethylbenzene, and styrene, or the analogous p-methoxy derivatives, from the irradiation of 2-phenylethyl bromide or 2-p-methoxyphenylethyl bromide, respectively. Possible mechanisms for the radiation-induced isotope position rearrangements are discussed.
THE THERMAL CIS–TRANS ISOMERIZATION OF CROTONONITRILE
Authors: Butler James N. , McAlpine Robert D.
Published: May 2006

The thermal cis–trans isomerization of crotononitrile has been studied in the gas phase at pressures from 0.2 to 20 mm and temperatures from 300 °C to 560 °C. For the equilibrium cis → trans, ΔH = 0.17 ± 0.12 kcal/mole, and ΔS = −0.39 ± 0.19 cal/mole °K. The isomerization is a homogeneous, unimolecular, reversible first-order reaction, the rate constant for the reaction cis → trans being given by[Formula: see text]The only side reaction with appreciable rate was a surface polymerization.
THE THERMAL CIS–TRANS ISOMERIZATION AND DECOMPOSITION OF METHYL CROTONATE
Authors: Butler James N. , Small Gerald J.
Published: May 2006

Methyl crotonate undergoes a homogeneous, unimolecular cis–trans isomerization in the gas phase at temperatures from 400 °C to 560 °C. The rate constant for the cis → trans reaction was found to be [Formula: see text]independent of pressure in the range from 0.1 mm to 10 mm. The equilibrium trans/cis ratio is approximately 4.5, independent of temperature, from 200 °C to 500 °C. Simultaneous free-radical reactions also occur, the most important of which are the isomerization to methyl vinylacetate, and the decomposition to give carbon dioxide and the various butene isomers. Side reactions gave carbon monoxide, methane, propylene, numerous other hydrocarbons, and various ethers.
DIRECT CARBONYLATION OF THE BENZOPHENONE SEMICARBAZONES AND BENZOPHENONE AZINE USING DICOBALT OCTACARBONYL
Authors: Rosenthal Alex , Millward S.
Published: May 2006

Benzophenone semicarbazone (I) reacted with carbon monoxide at about 4000 p.s.i. and at 235–245° in the presence of preformed dicobalt octacarbonyl as catalyst to yield 3-phenyl-phthalimidine (II), 3-phenyl-2- (N benzhydrylcarboxamido)phthalimidine (V), N,N′-dibenzhydrylurea (VI), and N-benzhydrylurea (VII). At 200–220° substance I gave compound VII, benzophenone azine (VIII), and benzophenone 4-benzhydrylsemicarbazone (IX). When the reaction temperature was further reduced to 175–185°, compound I did not produce the carbonylation product obtained in the second experiment but only the degradation and reduction products VIII, and IX, respectively. Carbonylation of benzophenone azine at 235–245° produced 3-phenylphthalimidine, whereas that of benzophenone 4-benzhydrylsemicarbazone at the same temperature yielded 3-phenylphthalimidine and 3-phenyl-2-(N-benzhydrylcarboxamido) phthalimidine. Independent syntheses of the last compound and of benzophenone 4-benzhydrylsemicarbazone are described.
NUCLEAR REACTIONS INDUCED IN TANTALUM BY PROTONS OF ENERGY UP TO 84 MEV
Authors: Rao C. L. , Yaffe L.
Published: May 2006

Nuclear reactions induced in tantalum by protons of energy up to 84 Mev have been studied and excitation functions obtained for products formed by (p,xn), (p,pxn), (p,2pxn), and (p,3pxn) reactions. Radiation characteristics of the products were redetermined. Previously unreported γ-rays with energies 90 to 1050 kev have been found for W176, and 113 kev for W177. A new half-life of 2.7 ± 0.1 hr for W176 is reported. The cross sections for the (p,xn) reactions were compared with the values predicted by Jackson's schematic model and found to be in reasonable agreement. More complex reactions are discussed in the light of current nuclear theories.
TARTRATE COMPLEXES OF THE RARE-EARTH ELEMENTS II. THE dl- AND meso-TARTRATE COMPLEXES OF La, Ce, Pm, Tm, AND Y
Authors: Manning P. G.
Published: May 2006

The liquid-liquid distribution method has been used to measure the stability constants of the dl-tartrate complexes of La3+, Ce3+, Pm3+, Tm3+, and Y3+, and the meso-tartrate complexes of Ce3+ and Tm3+. Thenoyltrifluoroacetone was the organic phase extractant, and the aqueous phase, acetate buffered (pH = 4.53), was maintained at a constant ionic strength (0.0597) by means of sodium perchlorate.The order of stabilities for the two stages of ion association are[Formula: see text][Formula: see text]The b1/b2 values, where b is a stepwise stability constant defined as [Formula: see text]are lower (by factors of 4–8) for the dl-tartrates than for the meso-tartrate complexes. The b1/b2 ratios decrease as the ionic radius of the metal ion decreases, and for the dl-tartrates of Tb3+, Y3+, and Tm3+, the b1/b2 values are 5.3, 5.0, and 4.3 respectively. The enhanced stabilities of the 1:2 (ML2−) dl-tartrate chelates have been interpreted in terms of ligand–ligand hydrogen bridging in the 1:2 complex.
A VAPOR PRESSURE STUDY OF THE ALLOYS OF MANGANESE WITH COPPER
Authors: Peters B. F. , Wiles D. R.
Published: May 2006

The Knudsen effusion method has been applied in a study of the vapor pressures of manganese in equilibrium with copper–manganese alloys at high temperatures. The amount of manganese effused was determined by the use of radioactive Mn54. The odd behavior noted in this system at 20–30% Mn, observed in a number of studies of various physical properties, has been observed once more in the apparent activity of manganese. Some discussion is given of the Knudsen effusion method, particularly regarding some possible sources of error.
STUDIES WITH A PERFLUOROALKYL–SILICON COMPOUND
Authors: Clark H. C. , Kwon J. T. , Whyman D.
Published: May 2006

Some detailed chemical studies are described of dimethylbis(perfluoropropyl)silane (I), prepared from n-perfluoropropyllithium and dimethyldichlorosilane. The hydrolytic stability of (I) towards base is described, and pyrolyses in the temperature range 185–295°, leading to the formation of dimethyldifluorosilane, (CH3)2SiF2, and fluorocarbons, are discussed. Chlorination of (I) leads to stepwise chlorination of the CH3 groups, and even excess chlorine does not cause cleavage. Bromine does not react with (I). The reaction of (I) with iodine and catalytic amounts of aluminum in boiling toluene causes rapid cleavage of C3F7 as C3F7I. The mechanisms of some of these reactions are discussed.
NUCLEAR MAGNETIC RESONANCE STUDIES OF THE PROTONATION OF WEAK BASES IN FLUOROSULPHURIC ACID: II. AMIDES, THIOAMIDES, AND SULPHONAMIDES
Authors: Birchall T. , Gillespie R. J.
Published: May 2006

The proton magnetic resonance spectra of solutions of amides in fluorosulphuric acid confirm previous results which indicated that protonation of amides occurs on the carbonyl oxygen. A similar study of solutions of thioacetamide, thioacetanilide, thiourea, and N-methylthiourea provides conclusive evidence that the sulphur atom is protonated in these bases. In the case of N-methyl- and N,N′-dimethyl-p-toluenesulphonamide and sulphamide protonation occurs on nitrogen rather than on oxygen. It was not possible to obtain any conclusive evidence on the site of protonation of urea and N,N′-dimethylurea. Evidence is presented which indicates that thiourea and N-methylthiourea are diprotonated in solution in strong acids such as fluorosulphuric acid, and diprotonation of urea and N,N′-dimethylurea under the same conditions also seems very likely.
THE INCORPORATION OF PUTRESCINE INTO HYOSCYAMINE
Authors: Kaczkowski J. , Marion Léo
Published: May 2006

Putrescine-1,4-14C was fed to the excised root cultures of Datura metel L., and the alkaloids subsequently isolated. These consisted of hyoscyamine, hyoscine, and a base of undetermined constitution designated as alkaloid X. All three bases were radioactive. Degradation of the hyoscyamine revealed that ca. 8% of the radioactivity was present in the tropic acid moiety, but that all the radioactivity of the tropine moiety was located in the pyrrolidine ring. The implications of these results are discussed.
π-BONDING IN INORGANIC COMPOUNDS PART 5. DELOCALIZATION OF d-ORBITALS IN K2RuCl6 AND K2OsCl5
Authors: Westland A. D.
Published: May 2006

not available
PREPARATION AND PROPERTIES OF ISOMERIC 2,4-DINITROPHENYL DERIVATIVES OF ALPHA–EPSILON DIAMINOPIMELIC ACID
Authors: Jušić; D. , Roy C. , Schocher A. J. , Watson R. W.
Published: May 2006

not available
INDUCTIVE AND MESOMERIC EFFECTS IN SUBSTITUTED FULVENE AND PYRIDINE DERIVATIVES
Authors: Cartier J. P. , Sandorfy C.
Published: May 2006

The electronic charge distribution in substituted fulvene and pyridine derivatives is examined using the simple Hückel molecular orbital method. Parameters characterizing the electronegativity of the substituent and the carbon to which it is linked are varied in order to cover actually existing substituents.It is found that the nature of the inductive and mesomeric effects is not basically different from that in the case of benzene. The most negative sites in fulvene show a certain variation with the place of substitution. In pyridine they are the ortho and para carbons for meta substitution and the meta carbons for ortho and para substitution.
PROTONATED CARBONYL GROUPS: III. ANTIPYRINE SALTS
Authors: Cook Denys
Published: May 2006

Salts of antipyrine (2,3-dimethyl-1-phenyl-5-pyrazolone) with halogen acids have been prepared and their infrared spectra from 4000 to 650 cm−1 recorded. Stoichiometrically they are normal 1:1 salts. Identification of bands due to vibrations of the protonating hydrogen atom has been aided by replacement with deuterium atoms. It is concluded that protonation occurs at the carbonyl group from the presence of a doublet (due to correlation field splitting) at 1320 and 1220 cm−1, attributed to the in-plane hydrogen-bending mode. The OH stretching vibration gives rise to bands between 2278 and 2720 cm−1 in the different salts. Out-of-plane hydrogen-bending mode absorptions are observed between 840 and 770 cm−1.More complex acids (HAsF6 etc.) give the anomalous 2 base:1 acid salts, characterized by strong absorption below 1400 cm−1, which probably contain strong, possibly symmetrical, hydrogen bonds.
THE REACTION OF tert-BUTOXY RADICALS WITH 2,6-Di-tert-BUTYL-4-METHYLPHENOL AND 2,6-Di-tert-BUTYLPHENOL
Authors: Ingold K. U.
Published: May 2006

The products of the reaction of t-butoxy radicals with 2,6-di-t-butyl-4-methylphenol and 2,6-di-t-butylphenol in carbon tetrachloride have been analyzed quantitatively. There is a satisfactory agreement between the measured and calculated yields of t-butanol with both phenols. The deuterium isotope effect (kh/kd) for abstraction of the phenolic hydrogen from 2,6-di-t-butyl-4-methylphenol is about 6.4.
THE EFFECT OF SUBSTITUENTS ON THE RELATIVE RATES OF REACTION OF tert-BUTOXY RADICALS WITH PHENOLS IN CARBON TETRACHLORIDE AND IN CHLOROBENZENE
Authors: Ingold K. U.
Published: May 2006

The relative rates of hydrogen abstraction from substituted phenols by t-butoxy radicals can be correlated with the σ+ constants of the substituents. The effects of an aromatic solvent (chlorobenzene) and of ortho-alkyl substituents on the reactivities of the phenols and on the transition state of the reaction are discussed.
A NEW MUSTARD OIL GLUCOSIDE SYNTHESIS: THE SYNTHESIS OF GLUCOTROPAEOLIN
Authors: Benn M. H.
Published: May 2006

A new synthesis of mustard oil glucosides is described, illustrated by the synthesis of glucotropaeolin. This synthesis, based on the reaction of thiols with nitrile oxides, leads to a conclusion concerning the stereochemistry about the carbon–nitrogen double bond in the mustard oil glucosides.
REARRANGEMENT STUDIES WITH C14: XVII. A REINVESTIGATION OF THE REACTION OF 2-PHENYLETHYL-1-C14 BROMIDE WITH MAGNESIUM AND COBALTOUS BROMIDE IN REFLUXING ETHER
Authors: Thornhill D. P. , Lee C. C.
Published: May 2006

Treatment of 2-phenylethyl-1-C14 bromide with magnesium and cobaltous bromide in refluxing ether gave ethylbenzene and styrene with no isotope position rearrangement. The results are contrary to those reported by Smith and Anderson. It was also found that oxidation of styrene-β-C14 with concentrated nitric acid gave p-nitrobenzoic acid containing 3–4% of the original styrene activity. Nitric acid oxidation of "regenerated styrene" from labeled styrene dibromide under different conditions gave 5.7–37.8% rearrangement. The mechanistic implications of the experimental results are discussed.
REACTIONS OF ORGANOTIN COMPOUNDS: I. THE STABILITY OF DIMETHYLTIN DIHYDRIDE, AND ADDITIONS TO SOME FLUORO-OLEFINS
Authors: Clark H. C. , Furnival Sharon G. , Kwon J. T.
Published: May 2006

The effect of heat and ultraviolet irradiation on dimethyltin dihydride is reported. At 120°, the major decomposition products are (CH3)3SnH, Sn, and H2, with a small amount of (CH3)6Sn2. At 130° under ultraviolet light, decomposition is much more rapid giving (CH3)3SnH, Sn, and H2, and an appreciable quantity of (CH3) 4Sn. If the dihydride is maintained under these conditions for a longer period (40 hours), (CH3)6Sn2 is formed in place of (CH3)3SnH, and other products are (CH3)4Sn, Sn, and H2. Negligible decomposition occurs at 25° even under irradiation.The ready addition of C2F4 to (CH3)2SnH2 gives the first reported mono-addition product of an organotin dihydride, (CH3)2SnH(C2F4H), as well as (CH3)2Sn(C2F4H)2. Physical and chemical properties of these compounds are described. The additions of (CH3)2SnH2 to CF2CFH, CF2CH2, and CF2CFBr are reported and the results interpreted in terms of the formation of unstable mono-addition products, (CH3)2SnH(C2FnXmHp). Surprisingly, these species decompose through the exchange of halogen and hydrogen between (CH3)2SnH2 and the olefin. Thus, usual products from the reaction of (CH3)2SnH2 with CF2CFBr are (CH3)2SnBr2 and CF2CFH, with some (CH3)3SnBr.
THE STRUCTURE OF CYCLOHEXYLIDENEMALONONITRILE DIMER
Authors: Weir M. R. S. , Hyne J. B.
Published: May 2006

not available
LES DIMÉTHYL-6,6 ET DIMÉTHYL-7,7 DÉCALONES-2 cis ET trans
Authors: Bruderlein Hélène , Dufort N. , Favre H. , Liston A. J.
Published: May 2006

not available
HALOGEN MIGRATION AND ELIMINATION IN THE CLAISEN REARRANGEMENT OF ALLYL 2,6-DIHALOPHENYL ETHERS
Authors: Piers E. , Brown R. K.
Published: May 2006

A study has been made of some factors affecting the migration or elimination of halogen in the Claisen rearrangement of allyl 2,6-dihalophenyl ethers.In the thermal rearrangement of allyl 2,6-dichlorophenyl ether, carried out in a number of solvents of different dielectric constant, halogen migration proceeds somewhat better in highly polar solvents. However, a competitive reduction to the monohalogenated allylphenol occurs in the presence of oxidizable solvents and/or products. The reaction is also complicated by the catalytic effects of certain solvents and the phenolic products, which give results similar to those obtained with Lewis acids. Stannous chloride acts as a Lewis acid and catalyzes the rearrangement of allyl 2,6-dichlorophenyl ether with simultaneous halogen rearrangement. As well, a competitive reductive removal of the halogen takes place. Results from the rearrangement of allyl 2,6-dibromophenyl ether with zinc chloride and of allyl 2,6-dichlorophenyl ether with zinc bromide, as well as those from the stannous chloride reactions indicate that the halogen migration takes place not only by an allylic shift but also via a competitive halogen substitution probably occurring by an Sn2′ pathway possibly assisted by a zinc halide bridge mechanism and/or an ionic species such as [Formula: see text].
THE METHYL 3-NITRO-3-DEOXY- AND 3-AMINO-3-DEOXY-ARABINOPYRANOSIDES
Authors: Baer Hans Helmut , Ahammad Alauddin
Published: May 2006

The nitromethane cyclization of L′-methoxy-diglycolic aldehyde was shown to furnish methyl 3-nitro-3-deoxy-α-L-arabinopyranoside and methyl 3-nitro-3-deoxy-β-D-arabino-pyranoside as coproducts of the previously obtained -β-D-ribo isomer. As expected, the enantiomorphic dialdehyde, D′-methoxy-diglycolic aldehyde, afforded the corresponding α-D- and β-L-arabino derivatives in addition to the β-L-ribo isomer. Catalytic hydrogenation of the four new nitroglycosides gave the corresponding aminoglycoside hydrochlorides. The 3-amino-3-deoxy-D- and L-arabinose hydrochlorides were obtained from their glycosides by hydrolysis and crystallized as mutarotating β-forms.The spontaneous epimerisation, in aqueous solution, of aci-nitropentoside sodium salts was investigated.
OXIDATION OF N,N-DIMETHYLANILINE: I.THE REACTION WITH BENZOYL PEROXIDE
Authors: Graham Donald M. , Mesrobian Robert B.
Published: May 2006

The reaction of N,N-dimethylaniline (A) with benzoyl peroxide (P) has been shown to exhibit complex kinetics. The observed rates of peroxide decomposition between 0° and 25 °C could be described by the relation −d[P]/dt = ka[A][P]+kb[A]1/2[P]3/2. An unstable Würster salt of tetramethylbenzidine was shown to be one of the main products of the reaction, and a mechanism has been postulated which is consistent with the observed kinetics, involving tetramethylbenzidine as a reaction intermediate.
THE KINETICS OF THE THERMAL REACTIONS OF ETHYLENE OXIDE
Authors: Neufeld M. Lynne , Blades Arthur T.
Published: May 2006

The thermal reactions of ethylene oxide in the presence of an excess of propylene have been studied as a function of pressure and it has been found that there are two sets of products, acetaldehyde and free radicals, presumably methyl and formyl. These products are believed to arise from an excited acetaldehyde intermediate. Some evidence has been obtained for the occurrence of a surface-catalyzed rearrangement to acetaldehyde but the free radical products are uninfluenced by surface.
ANTINEOPLASTIC AGENTS: IX. N-BENZYL-N-BIS(2-HALOETHYL)AMINES
Authors: Pettit George R. , Blonda David S. , Harrington Ernest C.
Published: May 2006

A number of N-bis(2-chloroethyl)amines and three N-bis(2-iodoethyl)benzylamines have been prepared for cancer chemotherapy studies. The chloro-nitrogen mustards were readily obtained by aluminum chloride – lithium aluminum hydride reduction of the corresponding N-bis(2-chloroethyl)amides. A convenient procedure for converting N-bis(2-chloroethyl)-benzylamine hydrochlorides to N-bis(2-iodoethyl)benzylamine hydroiodides, employing sodium iodide, was also developed.
POSSIBLE INTRAMOLECULAR VAN DER WAALS CONTRIBUTIONS TO PROTON AND CARBON-13 SHIFTS IN ALIPHATIC AND AROMATIC HALOGEN COMPOUNDS
Authors: Schaefer T. , Reynolds W. F. , Yonemoto T.
Published: May 2006

The chemical shifts of protons and carbon-13 nuclei in aliphatic and aromatic halogen compounds are considered on the basis of inductive, magnetic anisotropy, and intramolecular dispersion effects. It is suggested that a model based on all three effects is more consistent with experiment than a model based on the first two effects only. The dispersion effects in general cause a low-field shift and seem to outweigh magnetic anisotropy effects in some cases.
SYNTHESES AND POLYMERIZATION OF α-TRIMETHYLSILYL ACRYLIC MONOMERS
Authors: Ottolenghi Ariel , Fridkin Mati , Zilkha A.
Published: May 2006

α-Trimethylsilyl acrylic acid and its methyl ester were prepared in good yield starting from 1,2-dibromoethyltrimethylsilane. These monomers were polymerized with difficulty by free radicals to viscous polymers, but gave solid copolymers with styrene. The methyl ester was also a weak monomer in anionic polymerization. This non-reactivity is due to the steric effect of the α-trimethylsilyl group adjacent to the double bond.
STEREOCHEMISTRY OF ARSENIC: PART XII. BIS(DIPHENYLARSENIC) OXIDE
Authors: Cullen W. R. , Trotter J.
Published: May 2006

Crystals of bis(diphenylarsenic) oxide are monoclinic, with four molecules in a unit cell of dimensions a = 11.48, b = 30.2, c = 5.97 Å, β = 93.8°, space group P21/n. The structure has been determined from projections along the a and c axes, using Fourier and difference syntheses. The As—O—As angle is 137°, the increase from the normal oxygen valency angle probably being a result of pπ—dπ bonding involving arsenic 4d orbitals. The As—O distance is 1.67 Å, and all the other bond lengths and angles are normal. The orientations of the substituent phenyl groups have been determined.
EFFECT OF NON-ZERO EXTINCTION COEFFICIENT ON ABSTRACTION–RECOMBINATION RATE RATIOS IN PHOTOCHEMICAL SYSTEMS
Authors: Pritchard H. O. , Pritchard G. O.
Published: May 2006

The data of Marjury and Steacie on the photolysis of acetone and acetone-d6in the presence of H2and D2respectively have been re-analyzed in terms of the integrated rate equations. It is concluded that only part of the discrepancy between the results for the methyl and hydrogen reaction can be accounted for in this way.In an appendix, it is shown that for high extinction coefficients, the integrated rate expression reaches a limit which may sometimes be attainable experimentally without undue complication from diffusion effects.
THE PREPARATION OF SOME THIOSEMICARBAZONES CONTAINING THE s-TRIAZINE RING
Authors: Gingras B. A. , Suprunchuk T. , Bayley C. H.
Published: May 2006

The reaction between cyanuric chloride and aliphatic thiosemicarbazones results in the formation of 1:1 adducts containing a dichloro-s-triazine ring. Chemical evidence, infrared spectroscopy, and microbiological studies indicate that the addition of the triazine ring takes place at the N2 atom of thiosemicarbazones. Since cyanuric chloride failed to react similarly with aromatic thiosemicarbazones, a different type of condensation product was obtained by another method, in which cyanuric chloride was first condensed with o-, or p-hydroxybenzaldehyde to give 1:3 adducts containing free carbonyl groups. Reaction of these compounds with thiosemicarbazide gave the corresponding tri-thiosemicarbazones.
THE STRUCTURE OF BIKHACONITINE
Authors: Tsuda Y. , Marion Léo
Published: May 2006

Aconitum spicatum Stapf has been found to contain two major alkaloids, pseudaconitine and bikhaconitine. The latter (C36H51O11N) contains one free hydroxyl, four aliphatic methoxyl groups, one acetic and one veratric ester group, while the former (C36H51O12N) contains the same substituents plus a second free hydroxyl. Like pseudaconitine, which forms a pyroderivative hydrolyzable to pyropseudaconine, which can be isomerized to isopyropseudaconine, bikhaconitine gives rise to pyrobikhaconitine, pyrobikhaconine, and isopyrobikhaconine. Bikhaconitine was assumed to differ from pseudaconitine in lacking one secondary hydroxyl. The correctness of this assumption was proved by the conversion of pseudaconitine into bikhaconitine and further to triacetylbikhaconine. This correlation establishes the structure of bikhaconitine and also, since pseudaconitine had previously been correlated with aconitine, establishes its absolute configuration.
INVESTIGATION OF THE INFLUENCE OF SPACE CHARGE ON THE ANODIC OXIDATION OF ALUMINUM, A TYPICAL VALVE METAL
Authors: Dignam M. J. , Ryan P. J.
Published: May 2006

Measurements of the time derivative of the anodic overpotential of superpurity aluminum during anodic oxidation were made at various constant current densities. The data have been interpreted in terms of the variation of electric field strength with position in the oxide film. The analytic form of the profile of the electric field strength in the oxide film was deduced, assuming the high field Frenkel defect model. The data were found to be incompatible with the theoretical profile, providing, therefore, evidence against this model. The data are only consistent with a model for the transport process in which the concentration of ionic current carriers at a position in the oxide remote from the metal interface is independent of the field strength. A new model, proposed recently by Dignam to explain transient ionic conduction phenomena, is consistent with this conclusion.
AROMATIC SUBSTITUTION: PART V. THE MECHANISM OF THE REACTION OF PHENYLLITHIUM WITH PYRIDINES. DEUTERIUM ISOTOPE EFFECT STUDIES
Authors: Abramovitch R. A. , Giam Choo-Seng
Published: May 2006

The ratios of isomers formed in the reaction of 3-alkylpyridines with phenyllithium under various conditions appear to be invariant within the limits of experimental error. A number of experiments, including the reaction of phenyllithium with 3-picoline-2d and with an excess of a mixture of pyridine and pyridine-2d, are described which establish that the hydride ion elimination stage in these nucleophilic aromatic substitutions is not important in determining the observed orientation and that the addition stage is either virtually irreversible or that the equilibrium lies far on the product side and is not rapidly reversible. A convenient new procedure is described for working up the reaction mixtures.
THE PREPARATION OF SOME FLUORO-NITRO-ANTHRAQUINONES AND THEIR REDUCTION TO AMINO-FLUORO-ANTHRAQUINONES
Authors: Valkanas G.
Published: May 2006

not available
N.M.R. STUDIES OF BRIDGED RING SYSTEMS. I. CARBON-HYDROGEN SPIN COUPLING CONSTANTS IN BICYCLO[2,2,1]HEPTANE DERIVATIVES
Authors: Tori K. , Muneyuki R. , Tanida H.
Published: May 2006

not available
SOME REACTIONS OF CHROMIUM TETRAFLUORIDE
Authors: Clark H. C. , Sadana Y. N.
Published: May 2006

The preparation of chromium tetrafluoride reported by von Wartenberg has been repeated, and some physical and chemical properties have been studied. Chromium tetrafluoride is surprisingly inert and does not react with ammonia, sulphur di- or trioxide, pyridine, halogen fluorides, or selenium tetrafluoride at ordinary temperatures. In boiling bromine trifluoride or selenium tetrafluoride, chromium tetrafluoride is reduced to lower fluorides, while a refluxing mixture of bromine tri- and pentafluorides converts CrF4 to CrOF3•0.25BrF3. Chromium (IV) fluoride complexes of the types ACrF5 (A = K, Rb, or Cs) and A2CrF6 (A = K or Cs) have been prepared and their magnetic moments and lattice constants have been determined.
THE CHEMISTRY OF APIOSE. PART I
Authors: Williams D. T. , Jones J. K. N.
Published: May 2006

D-Apiose, D-xylose, and 2-O-methyl D-xylose have been identified as components of polysaccharides of ZosteramarinaL.D-Apiose has been synthesized by a new procedure which clarifies the stereochemistry at C3 of the D-apiose molecules and which gives a new general method for the synthesis of branched chain sugar alcohols.
INFRARED ABSORPTION OF SOLID PHOSPHINE
Authors: Hardin A. H. , Harvey K. B.
Published: May 2006

The infrared absorption of solid phosphine has been measured in the region of 4 °K to 68 °K. An hitherto unreported transition at about 10 °K has been observed. Above this temperature the spectrum is characteristic of a disordered system; below 10 °K the absorption arising from the symmetric vibrational modes exhibits a fine structure composed of sharp lines. The large number of lines attributed to v2 are interpreted as arising from inversion doubling, indicating a residual disorder in the system.
GUM JEOL: THE STRUCTURE OF THE DEGRADED GUM DERIVED FROM IT
Authors: Bhattacharyya A. K. , Rao C. V. N.
Published: May 2006

Gum Jeol has been shown to be composed of residues of D-galactose, L-arabinose, and D-galacturonic acid. On mild acid hydrolysis the gum gave an aldobiouronic acid, viz. 3-O-(D-galactopyranosyl uronic acid)-D-galactopyranose. Hydrolysis of the fully methylated degraded gum yielded 2,3,4,6-terra-(3 moles); 2,3,4-tri-(2 moles); 2,4-di-(1 mole); and 2-O-methyl-D-galactose (1 mole) in the neutral fraction of the hydrolyzate. The reduced acidic fraction yielded 2,3,4-tri-(2 moles) and 2,4-di-O-methyl-D-galactose (2 moles). Based on these results a partial structure of the degraded gum has been proposed, the additional evidence of which was deduced from periodate oxidation studies of the degraded gum.
THE SYNTHESIS OF AROYL METHYL KETONES AS LIGNIN MODEL SUBSTANCES
Authors: Pepper J. M. , Saha Maitreyi
Published: May 2006

A series of aroyl methyl ketones (ArCOCOCH3 in which Ar was phenyl, p-hydroxyphenyl, p-methoxy phenyl, 4-hydroxy-3-methoxyphenyl, 3,4-dimethoxyphenyl, 4-hydroxy-3,5-dimethoxyphenyl, and 3,4,5-trimethoxyphenyl) has been prepared by the oxidation, using selenium dioxide, of the correspondingly substituted benzyl methyl ketones.
THEORETICAL STUDIES ON THE ELECTRONIC SPECTRA OF SUBSTITUTED AROMATIC MOLECULES: PART II. SEMIEMPIRICAL SELF-CONSISTENT FIELD CALCULATIONS ON ANILINE
Authors: Bloor J. E. , Daykin P. N. , Boltwood P.
Published: May 2006

The results of 14 calculations on the aniline molecule using different choices of parameters within the framework of the semiempirical SCFMO method have been carried out using an automatic Fortran 1A program written for an I.B.M. 1620 computer. It has been shown that the approximation of using the valence state ionization potential as a measure of the core integral of a heteroatomic substituent underestimates the amount of electron transfer between substituent AO and the benzene MO's. By adjusting this core integral empirically or by using a variable electronegativity MO approach it has been found possible to obtain, for the same set of parameters, agreement between experiment and theory for: the first two electronic transitions in the vapor state (4.23–4.38 ev and 5.22–5.41 ev), the change in ionization potential relative to benzene (AI = 1.54 ev), and the electron density para to the amino group (ρ4π = 1.059). It was not found possible to calculate values for the π-electron dipole moment and oscillator strengths which agreed, for any reasonable choice of parameters, with experimental values.
THE POSSIBLE USE OF 14C-LABELED N-ETHYLMALEIMIDE FOR THE ESTIMATION OF SULPHYDRYL GROUPS
Authors: Lee C. C. , Samuels E. R.
Published: May 2006

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THE PHOTOCHEMICAL ADDITION OF CYCLOHEXENE TO DIACETYL AND ETHYL PYRUVATE
Authors: Jolly P. W. , Mayo P. de
Published: May 2006

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SOME CHEMISTRY OF HETERATISINE
Authors: Edwards O. E. , Ferrari C.
Published: May 2006

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THE ACTIVITY PRODUCT OF FERRIC HYDROXIDE BY TURBIDIMETRY
Authors: Platford R. F.
Published: May 2006

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A MODIFIED SYNTHESIS OF TETRAPHENYLCYCLOBUTADIENE PALLADIUM HALIDES
Authors: Maitlis P. M. , Games M. L.
Published: May 2006

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Δ11-STEROIDS
Authors: Zlegler P. , Amos A. A.
Published: May 2006

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THE OPTICAL ROTATION OF CERTAIN DERIVATIVES OF ASPIDOSPERMIDINE
Authors: McLean Stewart
Published: May 2006

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DIPHENYLMETHANB-3,3′-DICARBOXYLIC ACID
Authors: Beattie R. W. , Manske R. H. F.
Published: May 2006

The major condensation product of benzoic acid with formaldehyde in the presence of sulphuric acid was shown to be diphenylmethane-3,3′-dicarboxylic acid.
L'EFFET RÉFLEXE DANS LE BICYCLO[3.2.1]OCTANEDIOL-2β,4 β
Authors: Durocher J. G. , Favre H.
Published: May 2006

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SPECTROSCOPIC STUDIES OF ALCOHOLS: I. METHANOL-BASE ADDUCTS IN DILUTE CCl4 SOLUTION
Authors: Krueger P. J. , Mettee H. D.
Published: May 2006

The fundamental νOH shifts and association constants for methanol hydrogen bonded to some relatively weak proton acceptors (alkyl halides, aryl halides, aromatic hydrocarbons) are reported for standardized conditions in CCl4 solution, and the data are compared with similar measurements involving some relatively strong bases (containing N or O acceptor atoms) under the same conditions. The general usefulness of hydrogenic frequency displacements of the donor species as a measure of the basicity of the acceptor species is questioned.
SPECTRAL AND CHEMICAL PROPERTIES OF β- AND γ-FUNCTIONAL SILANES
Authors: Brook A. G. , Pierce J. B.
Published: May 2006

The synthesis of β- and γ-hydroxy- and keto-silanes is described, together with that of their carbon analogues. Unlike the α-isomers, the hydroxysilanes do not rearrange to silyl ethers, and the ultraviolet spectra of the silyl ketones is essentially the same as those of the carbon analogues, and unlike that of α-silyl ketones.β-Silyl ketones have a carbonyl-stretching frequency midway between that of ordinary ketones and α-silyl ketones. These effects are discussed.
SPECTROSCOPIC STUDIES OF ALCOHOLS: II. THE CONFORMATION OF 2-HALOETHANOLS IN CARBON TETRACHLORIDE SOLUTION
Authors: Krueger P. J. , Mettee H. D.
Published: May 2006

Of the five conformers predicted for 2-haloethanols, only two (halogen and OH trans and gauche) can be positively identified by high resolution infrared spectroscopy. From the temperature dependence of the relative intensities of the fundamental OH stretching bands of the trans and gauche forms of the compounds XCH2CH2OH2 where X = F, Cl, Br, and I, the gauche conformers are shown to be energetically favored in dilute carbon tetrachloride solution, with enthalpy differences between the two conformers of 2.07 ± 0.53, 1.20 ± 0.09, 1.25 ± 0.08, and 0.81 ± 0.09 kcal/mole respectively. Equilibrium constants and the conformational free energy and entropy differences are reported. Inter- and intra-molecular OH … X hydrogen-bond interactions are found to be similar in that the enthalpy increases in the order X = I < Br < Cl < F, and is linearly related to a decrease in the fundamental OH band shift, in contrast to the Badger–Bauer relationship. The molecular and thermodynamic factors governing conformational equilibria involving intramolecular hydrogen bonds are discussed.
MOLD METABOLITES: 2. THE STRUCTURE OF GRISEOVIRIDIN
Authors: Fallona M. Catherine , Mayo P. de , McMorris T. C. , Money T. , Stoessl A.
Published: May 2006

By a combination of selectively reductive and hydrolytic processes the structure of perhydrodethiogriseoviridin diacetate, obtained by Raney nickel reduction of griseoviridin diacetate, has been shown to be that of a macrocyclic lactonic peptide (III). Other hydrolytic and degradative experiments have ascertained the points of attachment of the cysteine moiety and the disposition of the functional groups in the aminodecanoic acid. The remaining three carbon atoms have been shown to be part of an unusual dehydro amino acid fragment, and the totality of this and other evidence has defined the structure of griseoviridin as represented in (XXVII).
THE pH AND pD DEPENDENCE OF THE SPONTANEOUS AND MAGNESIUM-ION-CATALYZED DECARBOXYLATION OF OXALACETIC ACID
Authors: Kosicki George W. , Lipovac Stanislava N.
Published: May 2006

Spectrophotometric studies of the spontaneous and magnesium-ion-catalyzed decarboxylation of oxalacetic acid in H2O and D2O have been carried out over a range of pH, pD, and magnesium ion concentrations.The rate of decarboxylation of oxalacetic acid depends on the proposed equilibrium system between the acid anion and magnesium chelate under a variety of conditions.The absorbancy indexes and the apparent equilibrium constant of the keto and enol forms of the magnesium chelate were estimated from a combination of the kinetic and spectral data.
ANTIMONY TETRAFLUORIDE MONOFLUOROSULPHATE: PREPARATION, PROPERTIES, AND STRUCTURE
Authors: Gillespie R. J. , Rothenbury R. A.
Published: May 2006

When antimony pentafluoride is refluxed with sulphur trioxide, a new compound with the composition SDF5•SO3 is formed together with sulphuryl fluoride, disulphuryl fluoride, and small amounts of the higher polysulphuryl fluorides. This compound is a colorless, very viscous liquid. From the chemical analysis, the F19 N.M.R. spectrum, and the Raman and infrared spectra of the liquid it was concluded that the compound is antimony tetrafluoride monofluorosulphate SbF4(SO3F) and that it is highly polymerized in the liquid state by fluorosulphate bridges that can have either a cis or a trans orientation with respect to each other; the former occurring to a greater extent than the latter.
STEROIDS: VI. THE STEREOCHEMISTRY OF 4-ETHYL-4-METHYLCHOLEST-5-EN-3-ONE (II)
Authors: Just George , Richardson Keith St. C.
Published: May 2006

The stereochemistry of the title compound was determined.
STEROIDS: VII. THE SOLVOLYSIS OF 4,4-DIMETHYL-17β-ACETOXY-ESTR-5-EN-3-YL p-TOLUENESULPHONATE
Authors: Just George , Shortland F. E.
Published: May 2006

The solvolysis of the title compound resulted mainly in products of ring contraction. No product of methyl shift could be detected.
A CONVENIENT PREPARATION OF TRYPTOPHOL
Authors: Nogrady Thomas , Doyle Terrence W.
Published: May 2006

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H0 ACIDITY FUNCTIONS FOR NITRIC AND PHOSPHORIC ACID SOLUTIONS CONTAINING ADDED SODIUM PERCHLORATE
Authors: Lee Donald G. , Stewart Ross
Published: May 2006

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TERPENOIDS: V. SENEGENIN: FUNCTIONAL GROUPS AND PART STRUCTURE
Authors: Dugan J. J. , Mayo P. De , Starratt A. N.
Published: May 2006

Senegenin, the sapogenin from Polygalasenega has been shown to contain chlorine; it has the empirical formula C30OH45O6Cl. The oxygen atoms, contrary to earlier work, are contained in two carboxyl groups and two secondary hydroxyl groups. There is one isolated ethylenic linkage. The environment of the hydroxylic functions and one carboxyl group has been shown to be as in (XI).
THE BROMINOLYSIS OF CARBOHYDRATE IODIDES: I. ACETYLATED 6-DEOXY-6-IODO AND 2-DEOXY-2-IODO GLYCOSIDES
Authors: Lemieux R. U. , Fraser-Reid B.
Published: May 2006

Reaction of methyl 6-deoxy-6-iodo-α-D-glucopyranoside triacetate with an excess of bromine in glacial acetic acid; N in potassium acetate, gave a 1.1:1 mixture of the products resulting from replacement of the iodine by bromine and by acetoxy group, respectively. When 2 moles of silver acetate were present per mole of bromine, the reaction was much more rapid and only methyl α-D-glucopyranoside tetraacetate was formed. The brominolysis of methyl 2-deoxy-2-iodo-α-D-mannopyranoside triacetate proceeded at a useful rate only when catalyzed by silver acetate. The main product of the reaction appeared to be methyl 3-acetoxy-2-bromo-2-deoxy-α-D-arabino-hexopyranoside triacetate. The compound could be converted by way of sodium borohydride reduction to methyl 2-bromo-2-deoxy-α-D-altropyranoside and by way of zinc dust reduction to methyl 2-deoxy-α-D-erythro-hexopyranoside-3-ulose diacetate. About 20% of the reaction proceeded with migration of the methoxy group to the 2-position to yield 2-O-methyl-D-glucose tetraacetate. The mechanisms of these reactions are discussed.
SYNTHESIS OF THE 2,4-DI-O-METHYL TETROSES
Authors: Dutton G. G. S. , Slessor K. N.
Published: May 2006

The four isomeric 2,4-di-O-methyl tetroses were prepared by periodate oxidation of known methylated sugars. 2,4-Di-O-methyl-D- and L-erythroses were prepared from 4,6-di-O-methyl-D-glucose and 3,5-di-O-methyl-L-arabinose respectively. 2,4-Di-O-methyl-D- and L-threoses were prepared from 3,5-di-O-methyl-D-xylose and 1,4,6-tri-O-methyl-L-sorbose.The tetroses were characterized by their crystalline 2,4-dinitrophenylhydrazones. The RFand RGvalues of the free sugars were recorded in a variety of solvents including a silica gel thin-layer chromatography system.
ARSENIDES OF THE TRANSITION METALS: VII. THE PALLADIUM–ARSENIC SYSTEM
Authors: Saini G. S. , Calvert L. D. , Heyding R. D. , Taylor J. B.
Published: May 2006

In the Pd–As system the existence of seven intermediate phases, PdAs2, α-Pd2As, β-Pd2As, Pd5As2, Pd2.65As, Pd3As, and Pd5As has been established by X-ray diffraction and thermal analysis. Single crystals of β-Pd2As and PdAs2 have been grown by slow cooling from a temperature above the liquidus and of Pd3As and Pd5As by halide vapor transport. PdAs2 is cubic, C2 (pyrite) structure, space group [Formula: see text] a = 5.983 ± 0.001 Å. α-Pd2As (stable below 455 °C) is monoclinic, a = 9.24 ± 0.01 Å, b = 8.47 ± 0.01 Å, c = 10.45 ± 0.01 Å β = 94°. β-Pd2As (stable above 455 °C) has the revised C22 (Fe2P) structure, space group [Formula: see text] a = 6.650 ± 0.003 Å, c = 3.583 ± 0.003 Å, c/a = 0.5388. Pd5As2 displays a form of polytypism and shows trigonal as well as hexagonal symmetry with different c parameters. Pd2.65As decomposes peritectically and its structure is unknown. Pd3As has tetragonal D0e (Fe3P) structure, space group [Formula: see text] redetermined lattice constants are a = 9.974 ± 0.002 Å, c = 4.822 ± 0.002 Å, c/a = 0.4834. Pd5As is C-face centered monoclinic, a = 5.514 ± 0.01 Å, b = 7.725 ± 0.01 Å, c = 8.427 ± 0.01 Å, and β = 99°± 5′.
THE THERMAL REVERSIBILITY OF THE MICHAEL REACTION: III. 1,5-DIKETONES AND ADDUCTS BEARING ACIDIC GROUPS
Authors: Allen C. F. H. , Happ G. P.
Published: May 2006

In this paper a number of known chemical facts obtained by classical methods are correlated with the mass spectra of compounds thermally decomposed in the heated inlet of the mass spectrometer. Of the 31 substances examined, 24 are dioxo compounds. Among them are the few and only Michael adducts previously known to undergo thermal reversal. Both normal and abnormal types of retrogression were found, but ketonic acids which could only regress normally, in a competing reaction, formed lactones by dehydration. A formally similar β-hydroxyketone dissociated both ways in a comparable manner. Esters were more stable than cyano ketones under the conditions employed.
THE FLUORINATION OF CHROMIUM(VI) OXIDE AND POTASSIUM DICHROMATE
Authors: Clark H. C. , Sadana Y. N.
Published: May 2006

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ÉTARD REACTION. IV. DEUTERIUM ISOTOPE EFFECT
Authors: Wheeler Owen H.
Published: May 2006

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THE EXTRACTION OF SCANDIUM BY MIXTURES OF OXINE AND NEUTRAL ORGANOPHOSPHORUS REAGENTS
Authors: Manning P. G.
Published: May 2006

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STUDIES ON THE SOLUBLE INTERMEDIATES IN THE HYDROLYSIS OF DIMETHYLTIN DICHLORIDE: EQUILIBRIUM CONSTANT FITTING WITH A HIGH SPEED DIGITAL COMPUTER
Authors: Tobias R. Stuart , Yasuda M.
Published: May 2006

The hydrolysis of (CH3)2SnCl2 has been studied in a medium 0.1 M in (Na+)Cl− by a potentiometric titration technique. The complexes formed by the hydrolysis reactions together with their formation constants have been determined by analysis of the 394 data sets using a high speed digital computer. The data can be fitted equally well over the range pH 1.5 to 9 by the four formation constants for (CH3)2SnOH+ (log *β11 = −3.245 ± 0.004), [(CH3)2SnOH]2+2 (log *β22 = −5.00 ± 0.02), (CH3)2Sn(OH)2 (log *β21 = −8.516 ± 0.004), and [(CH3)2Sn]4(OH)6+2 (log *β64 = −16.85 ± 0.02) or by the five constants for (CH3)2SnOH+ (log *β11 = −3.251 ± 0.004), [(CH3)2SnOH]2+2 (log *β22 = −5.05 ± 0.02), (CH3)2Sn(OH)2 (log *β21 = −8.535 ± 0.005), ((CH3)2Sn)2(OH)3+ (log *β32 = −9.81 ± 0.01), and ((CH3)2Sn)3(OH)4+2 (log *β43 = −11.52 ± 0.03). Thus there is little question about the existence in the solutions of the simple monohydroxo complex and its dimer or of the neutral dihydroxide. Only very low concentrations of species containing more than four tin atoms can exist in aqueous solution. In addition, the data determined previously for the hydrolysis of (CH3)2Sn(ClO4)2 in a medium 3.0 M in (Na+)ClO4− have been refined by the least squares procedure. These 762 data sets can also be fitted equally well by the set of constants log *β11 = −3.55 ± 0.01, log *β22 = −4.52 ± 0.01, log *β21 = −9.00 ± 0.01, and log *β64 = −16.14 ± 0.03 or log *β11 = −3.54 ± 0.01, log *β22 = −4.60 ± 0.02, log *β21 = −8.98 ± 0.01, log *β32 = −9.76 ± 0.06, and log *β43 = −10.40 ± 0.05. The tendency of dimethyltin dichloride to form polycondensed species in aqueous solution is slight, and there is no evidence for the formation of large rings or chains. The solid stannoxane which precipitates from chloride solution was studied by infrared and X-ray powder photography and is essentially the same as the compound obtained by reaction of (CH3)2SnO and (CH3)2SnCl2 in a 1:1 mole ratio in 95% ethanol. This corresponds to a slightly different product than that obtained by a 1:1 reaction of these compounds in benzene which gives ((CH3)2SnCl)2O. This is in accord with the observation that precipitation occurs only at a pH higher than that at which ((CH3)2SnOH)2+2 has attained the maximum concentration, and hence precipitation is occasioned by the formation of larger polycondensed species. A comparison of the perchlorate and chloride data also indicates that the tendency to form polycondensed species is reduced by the presence bf chloride ion. This is partially an ionic strength effect and partially a result of chloride complexing of the simple aquodimethyltin (IV) ion, and the first chloro-complexing constant was Estimated to be 28 1. mole−1.
REACTIONS OF DIETHYLBERYLLIUM AND DIETHYLBERYLLIUM TRIMETHYLAMINE WITH THE METHYLHYDRAZINES
Authors: Fetter Neil R.
Published: May 2006

The reactions of Et2Be and Et2Be:NMe3 with the methylhydrazines produce the following compounds: Et2Be:NMe3 and H2NNMeH give (EtBeMeNNH2)n, Et2Be and H2NNMeH give Be(MeNNH2)2, Et2Be and H2NNMe2 give Be(HNNMe2)2, Et2Be and HMeNNMeH give (EtBeMeNNMeH)n, Et2Be:NMe3 and HMeNNMe2 give approximately 50% Et2Be: HMeNNMe2 and 50% (EtBeMeNNMe2)n, Et2Be and HMeNNMe2 give primarily (EtBeMeNNMe2)n, and Et2Be and Me2NNMe2 give (Et2Be2):Me2NNMe2.
THE CONFORMATIONS IN SOLUTION OF trans-CYCLOHEXENE DIHALIDES AND cis- AND trans-1,2-CYCLOHEXANEDIOLS AND DERIVATIVES
Authors: Lemieux R. U. , Lown J. W.
Published: May 2006

trans-1,4,4-Trideuteriocyclohexene dichloride, dibromide, and diiodide and the 1,4,4-trideuterio-cis- and trans-1,2-cyclohexanediols together with their O-acetyl, O-tosyl, and O-isopropylidene derivatives were synthesized. Their nuclear magnetic resonance (NMR) spectral parameters were obtained with a spectrometer operating at 100 Mc.p.s. and employing double irradiation to establish the chemical shifts and the signs of the coupling constants. The interpretation of the data according to expectations based on the Karplus relationship, for dihedral angles and coupling constants, support the conformational equilibria assigned to the trans-dichloride and trans-dibromide of cyclohexene on the basis of dipole moment measurements (previously published results). The results indicate that trans-cyclohexene diiodide exists to about 84% in the diaxial conformation. In the case of the 1,2-cis-disubstituted cyclohexanes, the occurrence of the signal for the 3-hydrogen in trans relation to the 2-hydrogen at lower field than its geminal 3-hydrogen is assigned to the deshielding influence on the 3-hydrogen when in axial orientation by an opposing axial oxygen at the 1-position. Support for this contention was obtained by determination of the chemical shifts of the geminal hydrogens at the 3- and 5-positions of the cis- and trans-4-t-butyl-2,2,6,6-tetradeuterio-1-methylcyclohexanols. The conformational equilibria indicated for the 1,2-diol, 1,2-diacetoxy, and 1,2-ditosyloxy trans derivatives of 1,4,4-trideuteriocyclohexane by NMR parameters obtained from the spectrum of the O-isopropylidene derivatives of the trans-diol allowed conclusions regarding the non-bonded interaction energies involved. The Karplus relation had to be adjusted to the form, [Formula: see text] and [Formula: see text] to accommodate the results. Solvent effects on conformation are noted. Also, the investigation provided further evidence for the opposite signs of the coupling constants for geminal and vicinal hydrogens. A consideration of the chemical shifts observed for a variety of derivatives of cyclohexanol appears to indicate that intramolecular shielding effects are better accounted for on the basis of neighboring atomic groupings than on the basis of individual chemical bonds.
THE NUCLEAR MAGNETIC RESONANCE SPECTRA OF THE CARBOLINES
Authors: Abramovitch R. A. , Spenser I. D.
Published: May 2006

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1(7),8-p-MENTHADIENE EX PYROLYSIS OF β-PINENE
Authors: Steinbach L. , Theimer E. T. , Mitzner B. M.
Published: May 2006

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