Cyclohexene-sulfur bichloride adducts.: Stereochemical considerations.

The reaction of sulfur dichloride with cyclohexene produces two isomeric trans-adducts of meso and dl configurations. Derivatives of both series have been obtained and configurations have been assigned by means of pseudoasymmetry. General principles for the conformational analysis of systems which contain two inverting 6-membered rings have been discussed and the positions of conformational equilibria have been evaluated. The new conformational effect-stabilization of “heteroconformer”—has been found in the case of dl-bis(2-chlorocyclohexyl) sulfoxide.     

Thermodynamic behaviour of some glycol—water mixtures. Excess and partial volumes

Densities of water—glycol (mono- di-, tri- and tetraethyleneglycol) mixtures have been measured over the entire composition range at 298. 15 K. Mixtures involving monoethyleneglycol (MEG) have also been studied at different temperatures from 308.15 to 288.15 K. Deviations, V^E, from ideal volumes of mixing have been calculated: negative values are observed for all systems. They increase with the number of ether functions present in the organic molecule; a slight dependence of V^E towards temperature has been shown in the water—MEG mixtures. Partial molal volumes have also been calculated for both components of each system; they exhibit an extremum in the water-rich region.     

Organometallic oxime and allied derivatives II. Synthesis and properties of some tri-n-butylgermanium oximates

Tributylgermanium oximates have been prepared by reactions (a) of tributylgermanium chloride with (i) oximes in the presence of a base, (ii) sodium oximates, and (iii) organotin oximates, as well as (b) of tributylgermanium ethoxide and oxide with oximes.The derivatives have been characterised by elemental analyses, molecular weight measurements and IR spectra. Their reactions have been studied in detail.     

Phase equilibria and thermodynamics of coexisting phases in rare-earth element-iron-oxygen systems. II. The praseodymium-iron-oxygen system

The phase equilibria and the thermodynamics of coexisting phases in the PrFeO system have been studied using static and dynamic methods for attaining equilibrium with subsequent annealing and identification of the condensed phases by X-ray analysis. Equilibrium phase diagrams have been constructed to define the changes that take place in the PrFeO system on variation of the partial oxygen pressure, the temperature, and the composition of the initial mixture of oxides. An isothermal cross section at 1300°K and equilibrium diagrams of the type P_O2 = f(composition) with with one composition parameter fixed and T = f(composition) with P_O2 = constant have been constructed. It has been shown in the PrFeO system that only one ternary compound with perovskite structure, PrFeO₃, is formed, and furthermore, it is stable no matter how high the partial oxygen pressure.     

Thermodynamic studies of some binary mixtures containing a self-associated component. II. Excess volumes of some mixtures of tetrahydrofuran with alcohols

Excess volumes of mixing, V^E, for binary mixtures of tetrahydrofuran (THF) with methanol, ethanol, n-butanol, tert-butanol, 2-bromoethanol and ethylene glycol have been determined from the experimental density measurements at 298.15 K over the entire composition range. The V^E data follow the order: ethylene glycol < 2-bromoethanol < methanol < ethanol < n-butanol < tert-butanol. The results have been explained in terms of self-association and the hydrogen bond-donating abilities of alcohols.     

Biogenetically significant triterpenes in a species of meliaceae: Cabralea polytricha A.Juss.

Four triterpenes have been isolated from the fruits of Cabralea polytricha A.Juss. (Meliaceae). Two of them are new C₃₀ compounds whose structures have been established as the C-3, C-24 epimer of ocotillol-II and the C-24 epimer of ocotillone-II: 20S, 24S-epoxy-dammarane-3α,25-diol (IIa) and the corresponding 3-keto compound (IVa).     

Gas phase i.r. spectrum and vibro-rotational analysis of CH2BrCl

The gas phase i.r. spectrum of CH₂BrCl with natural isotopic abundance has been measured under medium resolution in the range 4000-350 cm⁻¹. Accurate inspection of the band contours enabled us to positively identify most of the observed absorptions including fundamentals, overtones and combinations. The frequency value of the lowest fundamental ν₆, lying below the spectral range examined, has been evaluated by difference of suitable combinations and “hot” bands. B- and C-type absorptions exhibiting resolved rotational structure have been analyzed in terms of perpendicular bands in the symmetric rotor approximation and molecular parameters have been deduced.     

Thermodynamics of molecular interactions in binary mixtures of non-electrolytes. Molar excess volumes

Molar excess volumes, V^E, for pyridine (A) + α-picoline (B), + β-picoline (B) and + γ-picoline (B) and benzene (A) + toluene (B), + o-xylene (B) and + p-xylene (B) and carbon tetrachloride (A) + n-heptane (B) have been measured dilatometrically as a function of temperature and composition and have been utilized to study B—B and B—B—B interactions in the presence of A via the Mayer—McMillan approach. A model has also been presented to account for these B—B and B—B—B interactions. The V^E data at 308.15 K have also been analysed in terms of the “graph theoretical” approach which describes the V^E data well for all these mixtures at 308.15 K. The “graph theoretical” approach has further been extended to successfully evaluate V^E data for a mixture at any temperature, T₂, when the V^E data at T₁ are known.     

Polysaccharides ofEremurus. XV. Structure of the glucomannan ofEremurus lactiflorus

Ten oligosaccharides have been isolated from the products of the partial hydrolysis of a native acetylated glucomannan obtained fromEremurus lactiflorus O. Fedtsch. Their structures have been studied with the aid of acid hydrolysis before and after reduction with NaBH₄, by the GLC method, and also by chromatography with markers. The compositions and sequence of the monomers in tetra- and heptaoligo-saccharides have been determined by the¹³C NMR method. The glucommannan ofE. lactiflorus differs from theEremurus glucomannans studied previously by the ratio of monosaccharides, the presence of 0-Ac groups, the degree of polymerization, and the presence of a cellobiose unit (Glcp-Glcp) in the polymer chain. The repeating unit consists of 14 hexose residues.     

Tetracyclic triterpenoids from Melia azedarach, L.—III

From petroleum ether extracts of the bark of M. azedarach four novel tetracyclic triterpenoids have been isolated and characterized to be C₃₀ compounds of the euphane (20R) series. Previously known triterpenoids from Meliaceae have all been 20S compounds. Kulinone 1 is the first known euphane or tirucallane (20S) derivative oxygenated in the D ring; kulactone 2, kulolactone 3 and methyl kulonate 4 are additionally oxygenated in the side chain. Compounds 2 and 3 have a 2-oxa-trans-bicyclo[3,3,0]-octanone structure.     

Simple NMR method for assigning relative stereochemistry of bridged bicyclo[3.n.1]-2-enes and tricyclo[7.n.1.0]-2-enes

The stereochemistry of syn and anti-forms of bridged bicyclo[3.n.1]-2-ene, tricyclo[7.n.1.0]-2-ene (n=1-3) and bicyclo[4.3.1]dec-7-ene derivatives can be assigned from the ¹³C chemical shift difference of the double bond. Both syn-9-R-bicyclo[3.3.1]non-2-enes and syn-13-R-tricyclo[7.3.1.0^2,7]tridec-2(7)-enes have a large shielding difference between sp² carbons, while the corresponding anti-forms have a smaller one. In contrast, 8-R-bicyclo[3.2.1]oct-2-enes and 12-R-tricyclo[7.2.1.0^2,7]dodec-2(7)-enes have an inverse correlation. The reason of this specificity is the influence of the γ-gauche effect on the chemical shift of C(2) atom. The GIAO theory has been applied to investigate the ¹³C chemical shifts. The conformational equilibrium in the formamide group of 13-formylamino-tricyclo[7.3.1.0^2,7]tridec-2(7)-enes has been studied.     

Two diasteoisomers of 5-hydroxy-6-methylpipecolic acid from seeds of Fagus silvatica L.

Two diastereoisomers of 5-hydroxy-6-methylpipecolic acid have been isolated from beechnuts. The configurations of the two amino acids have been assigned as (2S, 5S, 6S) (1) and (2S, 5R, 6S) (2). The determination of structure and configuration for the two new amino acids is mainly based on spectroscopic and rotatory evidence. The ¹³C-NMR and ¹H-NMR spectra of the three ionic forms of the two amino acids and of S-pipecolic acid and (2S, 5R)-5-hydroxypipecolic acid and the CD-curves of the cations and amfoions of 1, 2, and (2S, 5R)-5-hydroxypipecolic acid have been recorded.     

Cleavage of α-halo-substituted alkyl groups from silicon. The mechanism of catalysis by ammonia buffer

Kinetic studies have been made of the base-catalysed cleavage of α-dihalo-substituted alkyl groups from silicon in n-propanol—water in the presence of ammonia buffer. The separate rate constants for the concurrent base-catalysed and base-plus-nucleophile-catalysed processes have been determined for the compounds XC₆H₄(Me₂)SiCHCl₂ with X = H, p-MeO, p-Me, p-Cl, m-Cl, m-CF₃ and a good correlation with σ-constants found for both types of catalysis. Solvent isotope effects and steric effects of substituents have also been studied. Possible mechanisms are discussed.     

Two-color excitation of NO in a supersonic free jet. Autoionization of high rydberg states

High Rydberg states of NO above the ionization limit have been measured for the isolated molecule in a supersonic free jet by two-color multiphoton ionization. Three Rydberg series (ns, np and nf) were identified, which appeared by rotational and the vibrational autoionization. The rotational structures of the 13s(υ = 1), 13p(υ = 1) and 12f(υ = 1) states have been analyzed in detail. The fluorescence dip spectra for the intermediate A²Σ⁺(3sσ) state have been measured simultaneously and the cross sections of the one-photon absorption to the high Rydberg states from the A²Σ⁺(υ = 1) state have been determined.     

Spectra and structure of organophosphorus compounds: XVII. Infrared and Raman spectra. vibrational assignment and barriers to internal rotation for t-butylphosphine

The infrared spectra of gaseous and solid tertiary-butylphosphine, [(CH₃)₃CPH₂], have been recorded from 50 cm^?1 to 3500 cm^?1. The Raman spectra of gaseous, liquid and solid (CH₃)₃CPH₂ have been recorded from 10 to 3500 cm^?1. A vibrational assignment of the 42 normal modes has been made. A harmonic approximation of the methyl torsional barrier from observed transitions in the solid state gave a result of 4.22 kcal mol^?1 and 3.81 kcal mol^?1 in the gaseous state. Hot band transitions for the phosphino torsional mode have been observed. The potential function for internal rotation about the C-P bond has been calculated. The two potential constants were determined to be: V₃ = 2.79 ± 0.01 kcal mol^?1 and V₆ = 0.07 ± 0.01 kcal mol^?1.     

Syntheses of sulfoxide derivatives in the benzodiazine series. Diazines. Part 37

Syntheses of new sulfinylcinnolines, quinoxalines, quinazolines and phtalazines have been investigated starting from the appropriate halogenobenzodiazine derivatives. The latter were converted in one step to the corresponding sulfanyl benzodiazines which upon oxidation with m-CPBA led to the corresponding sulfoxide derivatives of benzodiazines in moderate to good yields. In parallel to this study, an improved method for the synthesis of 2-methylsulfinylquinoxaline starting from 2-sulfanylquinoxaline is also described and in the quinazoline series a synthetic route has been developed to prepare 2-tert-butyl-5-phenylsulfinylquinazoline with satisfactory yield as well as 2-tert-butyl-5-tert-butylsulfinyl-4(3H)-quinazolinone and 2-tert-butyl-8-tert-butylsulfinyl-4(3H)-quinazolinone.     

Cannabis sativa CBD Extract Shows Promising Antibacterial Activity against Salmonella typhimurium and S. newington

Products derived from Cannabis sativa L. have gained increased interest and popularity. As these products become common amongst the public, the health and potential therapeutic values associated with hemp have become a premier focus of research. While the psychoactive and medicinal properties of Cannabis products have been extensively highlighted in the literature, the antibacterial properties of cannabidiol (CBD) have not been explored in depth. This research serves to examine the antibacterial potential of CBD against Salmonella newington and S. typhimurium. In this study, we observed bacterial response to CBD exposure through biological assays, bacterial kinetics, and fluorescence microscopy. Additionally, comparative studies between CBD and ampicillin were conducted against S. typhimurium and S. newington to determine comparative efficacy. Furthermore, we observed potential resistance development of our Salmonella spp. against CBD treatment.     

The triplet state of photosynthetic pigments. I. Pheophytins

ZFS constants (in cm^?1) and decay rate constants for the lowest triplet state of pheophytins have been determined by ESR: pheophytin a: D = 341 ± 3,E = 33 ± 3, K_T = 1050 s^?1; pheophytin b: D = 358 ± 8, E = 46 ± 5, K_T = 630 s^?1; bacteriopheophytin: D = 256 ± 4, E = 54 ± 5/37 ± 5, K_T ≈ 4000 s^?1. In addition values for the decay rate constants and relative populating rates of the individual spin levels have been obtained; these numbers turn out to be appreciably different from those for the corresponding chlorophylls. For the series pheophytin a, b and bacteriopheophytin we find parallel behaviour with the corresponding chlorophylls. The effects of side group substitution and pyrrole ring reduction on the ZFS constant D can be understood by including configuration interaction between the excited states using the 4-orbital model. The change of the mean triplet decay constant K_T upon side group substitution and pyrrole ring reduction follows an energy gap law. Substitution of the central Mg-ion by two protons, however, causes K_T to increase; this is attributed to the introduction of an extra promoting mode - of the NH-group - and/or to the presence of low lying nπ^* states in pheophytins.     

Complexation chemistry. Double- and multi-1,3-alternate-calixcrowns

Metal ion complexation behavior in calix[4]crown multimers (mono, di, trimer) have been investigated through X-ray crystallography, two-phase extraction, and ¹H NMR measurement.     

Cryochemistry : edited by M. Moskovits and G.A. Ozin,John Wiley & Sons,New York,London, Sydney and Toronto, 1976, pp. xi + 532, price £25.85

The IR spectra of N₂F₄ solutions in liquid argon and nitrogen have been recorded and reanalyzed in the 3300–3550 cm^?1 region. The fundamental absorption bands of NF-stretching modes of both the gauche and trans isomers and the bands of the second order transition have been observed. These new IR data on the spectra of cryosystems and published Raman data allowed us to make an unambiguous interpretation of the NF₂-stretching vibrational bands for both the N₂F₄ conformers.