A serendipitous route to the benzidene nucleus. Structural elucidation by noeds.

The epimeric indenones (3) and (4) are readily synthesised and rapidly formed by treating bis(p-methoxyphenylcyclopropyl) ketone (2) with stannic chloride in nitromethane. The structure of (3) was determined by X-ray crystallography and that of (4) by NOEDS.     

Physicochemical processes occurring during the formation of cellulose diacetate membranes—research of criteria for optimizing membrane performance—III. Evaporation Rate And Equilibrium Phase Separation

The kinetics of acetone evaporation from films obtained by casting solutions of cellulose diacetate-acetone-water-inorganic additive have been analysed. Three successive regimes of evaporation have been identified. The first two are exponential and end, respectively, at critical times t₁ and t₂. Casting solution compositions have been determined both at the instant of phase separation (cloud point) and upon complete gelation. Also, the period of evaporation required to produce total film opacification has been measured for certain systems. These measurements have shown that time t₁ corresponds to polymer precipitation at the film surface, and that time t₂ corresponds to complete gelation of the medium. The results illustrate the effects of film thickness, casting temperature and “swelling” or “gelling” characteristics of the inorganic additive on times t₁ and t₂.     

Domestic crude oil resource appraisal

This paper endeavours to estimate the cummulative level of discovery and production of crude oil in the United States where the importance of price and technological change is considered. Two separate functional specifications for the cumulative level are hypothesized and estimated. The results suggest that between 170 and 180 billion barrels will be ultimately recoverable of which 117 billion barrels have been produced through the end of 1989.     

The rotational and vibrational spectra of 1,3-dithiole- 2-one

Microwave spectra of 1,3-dithiole-2-one show that the molecule has a planar equilibrium conformation. IR and Raman spectra are analysed to give the normal modes of vibration.     

Die Struktur der Grenzfl?che Kiesels?ure/Elektrolyt

Ohne Zusammenfassung     

Infrared and microwave spectra, molecular conformation and electric dipole moment of methyl thiolformate

The microwave spectrum (41-10 GHz) and the infrared spectrum (4000-50 cm⁻¹) of methyl thiolformate have been obtained and analyzed. The spectra are consistent with a single molecular conformation having a planar array of heavy atoms and with the alkyl group cis to the carbonyl group. The measured rotational constants are: A, 11042.22 MHz; B, 5118.27 MHz; C, 3562.03 MHz (κ = −0.5839). No internal rotation doublets were observed in the microwave spectrum for the ground vibrational state, which implies that the barrier hindering internal rotation of the methyl group is either much larger or much smaller than the corresponding value for methyl formate. If the former is true then a lower limit of 10.5 kJ mol⁻¹ may be placed on the barrier height.The dipole moment of methyl thiolformate was measured using the Stark effect to be 1.58 ± 0.05 Debyes (μ_A = 1.52 D; μ_B = 0.43 D) for the vapor, and for dilute solutions in benzene at 295 K the value of 1.6 ± 0.1 D was found from capacitance measurements.SCF computations using minimal basis sets of STO/3G atomic orbitals and extended basis sets of STO/4.31G atomic orbitals have been carried out for methyl thiolformate and methyl formate. Energy differences between rotational isomers and estimates of barrier heights are given together with the calculated dipole moments.