A rapid thermal cyclisation of ethane-1,2-bis-fatty amides and alcohol derivatives to Δ2-imidazolines with phenylphosphorodiamidate.

Brief heating of ethane-1,2-bis-fatty amides at 235 – 250° with phenylphosphorodiamidate gave high yields of 2-fattyalkyl-Δ²-imidazolines.     

Mobile-ion concentrations and mixed-alkali effects in β-alumina solid electrolytes

A theory of the mixed-alkali effect based on the weak electrolyte model is used in the analysis of conductivity isotherms in the Na/K β-alumina system. This gives mobile interstitialcy concentrations, [Na²⁺₂] or [Na⁺_i], which agree remarkably well with those obtained by Wolf from calculations based on changes in the Haven ratio, H_R. The high conductivity of β-alumina arises apparently from a high “defect mobility” rather than from the existence of quasi-liquid motions. Other consequences of the weak electrolyte theory are discussed.     

A database of lipid phase transition temperatures and enthalpy changes

The systematic study of the mesomorphic phase properties of synthetic and biologically derived lipids began some 30 years ago. In the past decade, interest in this area has grown enormously. As a result, there exists a wealth of information on lipid phase behavior, but unfortunately, these data have, until now, been scattered throughout the literature in a variety of books, proceedings, and journals. The data have recently been compiled in a centralized database with a view to providing ready access to the same and to the appropriate literature. The compilation facilitates review of what has thus far been accomplished and highlights what remains to be done in this active research area. As such, it represents a convenient summary of the existing data which, when evaluated, will enable us to identify where deficits exist in the data, to reveal the fundamental physicochemical principles upon which lipid phase behavior is based, and to understand more completely lipid phase relations in biological, reconstituted, and formulated systems. The compilation consists of a tabulation of all known mesomorphic and polymorphic phase transition temperatures and enthalpy changes for synthetic and biologically derived lipids in the dry and in the partially and fully hydrated states. Also included is the effect on these thermodynamic values of pH, and of salt and metal ion concentration and other additives such as proteins, drugs, etc. The methods used in making the measurements and the experimental conditions are reported. Bibliographic information includes complete literature referencing and list of authors. As of this writing, the database is current through June 1990 and contains 9500 records. Each record contains 28 fields. Here, we describe how the database originated, its scope and contents, data abstraction procedures, and issues relating to mesophase and lipid nomenclature, data analysis, and evaluation, and database maintenance and distribution.     

Vibrational spectra of fluorohafnate glass

We report the first detailed measurements of fundamental vibrational spectra in fluorohafnate glass. The Raman spectrum is dominated by a single relatively broad peak in the vicinity of 570–590 cm^?1 attributed to Hf-F stretching modes, while the infrared spectrum displays two prominent broad peaks. The location of the high frequency peaks is shown to be consistent with the observed position of the infrared absorption edge.     

The Debye-Falkenhagen theory of electrical relaxation in glass

The Debye-Falkenhagen-Tomozawa theory (DFT theory) of electrical relaxation in glass is reviewed. This theory interprets the principal electrical relaxation in ionically conducting glasses in terms of relaxation of Debye-Huckel ion atmospheres. Electrical relaxation data is presented to demonstrate that in typical alkali silicate glasses the concentration of free ions is too great for the DFT theory to hold. Further data in a series of borosilicate glasses containing Na₂O at the 0.01 mol% level offers evidence for the validity of the theory in the dilute alkali regime. However, a quantitative fit to the theory can only be made under the assumption that less than 8% of the sodium in the glass is present as free ions at 400°C. This result is discussed in terms of the Bjerrum theory of ionic association.     

Structural diversity for phosphine complexes of stibenium and stibinidenium cations

Reactions of trimethylphosphine or diphosphines with SbCl(3) in the presence of AlCl(3) or Me(3)SiSO(3)CF(3) give ligand stabilized stibenium and stibinidenium cations. The geometry at each antimony center reveals a variety of environments for antimony that describes new bonding and highlights new directions in the chemistry of the pnictogen elements.     

Synthesis,spectroscopic and structural characterization of the first mixed fluoro-bromo group 4 organometallic complex [{Cp*ZrF2Br}4] (Cp* = C5Me5)

[{Cp*ZrF₂Br}₄] is conveniently prepared in high yield from the reaction of [{Cp*ZrF₃}₄] with four equivalents of Me₃SiBr. In contrast the reaction of [{Cp*ZrF₃}₄] with Me₃SiI under identical reaction conditions leads to a mixture of [Cp*ZrI₃] and unreacted [{Cp*ZrF₃}₄]. The crystal structure of [{Cp*ZrF₂Br}₄] has been determined by X-ray diffraction studies. The compound crystallizes in the orthorhombic crystal system [a = 9.325(1), b = 23.483(3), c = 27.016(5) Å, α = β = γ = 90°, space group Ibam, Z = 4]. The tetrameric core structure of [{Cp*ZrF₂Br}₄] contains four zirconium atoms linked by alternating single and triple fluorine bridges. One terminal bromine atom is bonded to each zirconium. ¹H and ¹⁹FNMR spectroscopic data and structural features of the title compound are compared with those for the mixed fluoro-chloro complexes [{Cp*ZrF₂Cl}₄], [{Cp*ZrF₂Cl}₂{Cp*ZrFCl₂}₂] and the trifluoro complex [{Cp*ZrF₃}₄].