[en] Acetylene hydratase, a tungsten-containing hydroxylase that converts acetylene to acetaldehyde, has been purified and crystallized under anaerobic conditions

[en] We report measurements of self- and nitrogen-pressure broadening of the P(11) line in the ?₁ + ?₃ combination band of acetylene at 195 739.649 5135(80) GHz by absorption of radiation emitted by an extended cavity diode laser referenced to a femtosecond frequency comb. Broadening, shift and narrowing parameters were determined at 296 K. For the most appropriate, hard collision, model in units of cm^-1/atm, we find 0.146317(27), 0.047271(104) and -0.0070819(22) for the acetylene self-broadening, narrowing and shift, and 0.081129(35), 0.022940(74) and -0.0088913(25) respectively, for the nitrogen-broadening parameters. The uncertainties are expressed as one standard deviation (in parenthesis) in units of the last digit reported. These parameters are 2-3 orders of magnitude more precise than those reported in previous measurements. Similar analyses of the experimental data using soft collision and simple Voigt lineshape models were made for comparison.

[en] The main advances in the chemistry of acetylene in superbasic media achieved over the last five years are analyzed. Particular emphasis is placed on the ethynylation of aldehydes and ketones and C-, N- and O-vinylation. The cascade assembly of complex molecules in which ethynylation and vinylation are consecutive steps is considered. The bibliography includes 369 references

No abstract available

[en] Full text: A number of new compound esters of acetylenic raw by etherification of oil naphtenic acids with acetylene alcohols and glycols in the presence of the catalyst of cat ion exchange resin KY-2 have been synthesized. It is shown that obtained acetylene esters easily enter into the reaction of hydrosillicylatig, aminoomethylating, of oxidizing, dimerization and hydration generating the new derivatives of oil naphtenic acids and may be applied as anticorrosive additives to motor oils

[en] A high level ab initio calculation of the cis-trans isomerization barrier height in the first excited singlet electronic state of acetylene is found to agree very well with a recent experimental determination.

No abstract available

No abstract available

[en] Highlights: • Lamb-dips of 45 lines in the $v_1+3v_3$ band of ¹²C₂H₂ in the 786–793 nm region were recorded by cavity ring-down saturation spectroscopy. • Line positions were determined with an accuracy as good as 3.2 kHz (relatively $8\times {10}^{-12}$). The ground state combination differences obtained in this work agree with the most precisely reported results from the $v_1+v_3$ band near $1.5\mu$ m. • Upper energies of these transitions have an average shift of $0.01{\text{cm}}^{-1}$ compared to those recently derived from the MARVEL method. Lamb-dips of the ro-vibrational lines of ¹²C₂H₂ near 789 nm were recorded using cavity ring-down saturation spectroscopy. Calibrated by an optical frequency comb, frequencies of 45 acetylene lines were determined with an accuracy of $1.1\times {10}^{-7}$ cm${}^{-1}$ ($\delta \nu /\nu =8\times {10}^{-12}$), which is over two orders of magnitude more accurate than previous Doppler-limited studies. An averaged shift of about 0.01 cm${}^{-1}$ were found by comparing the upper energies obtained in this work to those recently presented by Chubb et al. from a MARVEL analysis.

[en] Decaying modes of a flame front propagation in narrow channel for acetylene–air mixtures were investigated experimentally using optical methods of diagnostics. Experiments were carried out using an open detonation channel of square cross section with transverse dimension of 3 mm and length of 1000 mm. It was connected to the detonation tube of 20 mm diameter and length of 3000 mm. A galloping decaying propagation of the combustion inside the narrow channel after the entry of a steady Chapman–Jouguet detonation into the channel was registered. It was shown that the propagation of detonation-like galloping combustion is possible in channels of subcritical size. Evolution of the flame front velocity was obtained. The time intervals of gallops and distance intervals were measured. After the decay of the detonation wave, the average velocity of the flame front decreases first to 1000 m/s, and then to 200 m/s. (paper)