[en] In this study, walnut processing by-product was served as filler to make three-layer plywood, and the physical-mechanical properties were also discussed. The results showed that the formaldehyde emission of plywood corresponding to walnut shell and walnut dregs decreased by 0.0542 mg/L and 0.066 mg/L, respectively. The properties of plywood filled with walnut dregs are better than that of walnut shell filler, and the formaldehyde emission of the corresponding plate is lower. At the same time, compared with flour, the wet bond strength of walnut shell plywood increased by 0.0332 MPa, and that of walnut dregs plywood decreased by 0.123 MPa, but they all met the national standards. (paper)

[en] The reaction mechanism between cyclopropenylidene and formaldehyde has been systematically investigated employing the MP2/6-311+G* level of theory to better understand the cyclopropenylidene reactivity with carbonyl compound. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. Energies of all the species are further corrected by the CCSD(T)/6-311+G* single-point calculations. It was found that one important reaction intermediate (INTa) has been located firstly via a transition state (TSa). After that, the common intermediate (INTb) for the two pathways (1) and (2) has been formed via TSb. At last, two different products possessing three- and four-membered ring characters have been obtained through two possible reaction pathways. In the reaction pathway (1), a three-membered ring alkyne compound has been obtained. As for the reaction pathway (2), it is the formation of the four-membered ring conjugated diene compound. The energy barrier of the rate determining step of pathway (1) is lower than that of the pathway (2), and the ultima product of pathway (2) is more stable than that of the pathway (1)

[en] Short communication

[en] High-velocity gas (50 km s^-1) has been observed in six transitions of formaldehyde toward the Orion infrared clusters. The region of the clusters has been mapped in the higher frequency transitions. The low-velocity emission probably arises from an ensemble of dense (approx.10⁷--10⁸) clumps. A similar density is required to reproduce the observed excitation of the high-velocity emission. The abundance of formaldehyde in the high-velocity gas [X(H₂CO)approx.10^-9] is similar to the abundance in the ambient cloud and about an order of magnitude higher than that in the ''hot core.'' Chemical reactions at the high temperatures expected from direct heating of the H₂CO by a passing shock should drastically lower its abundance. The survival of high-velocity formaldehyde requires acceleration of only modestly heated (i.e,<400 K) cloud material, perhaps in the form of clumps similar to those producing the low-velocity emission

[en] The equilibrium geometries of the lowest three triplet states of trans glyoxal (HCOHCO) have been predicted at the self-consistent-field (SCF) level of theory using a double zeta plus polarization (DZ+P) basis set, designated C,O(9s5p1d/4s2p1d), H(4s1p/2s1p). Two of the molecular structures thus predicted differ radically from the known ¹A/sub g/ ground state equilibrium geometry. Specifically the π→π* ³B/sub u/ electronic state may be best described by the valence structure :[RW4::xO::]

No abstract available

[en] In recent years, among the problems of anthropogenic pollution of nature, the problem of exposure to organic substances of different classes has attracted great attention. Therefore, it is important to study the laws of the photochemical formation of oxygen-containing organic molecules, taking into account the anomalous phenomena occurring in the atmosphere. During the photooxidation of methane in the atmosphere, the most common hydrocarbon formaldehyde is formed. The average life span of formaldehyde in the atmosphere is approximately three hours. A study was made of the kinetic laws of formation of oxygen-containing (formaldehyde, formic acid and acetone) hydrocarbons during the photochemical conversion of air-methane mixtures.

[en] In an attempt to understand the ordering of excited states of glyoxal the ¹A/sub g/ ground state and low-lying triplet states ³A/sub u/, ³B/sub u/, and ³B/sub g/ have been studied with ab initio correlated wavefunctions. A double zeta basis set was used in the configuration interaction calculations, and approx.6000 Slater determinants were selected for each electronic state. The predicted CI adiabatic excitation energies T/sub e/ are 21 800 cm^-1 (³A/sub u/), 25 100 cm^-1 (³B/sub u/), and 29 300 cm^-1 (³B/sub g/). The effects of d functions and higher (than double) excitations (unlinked clusters) have also been evaluated. For the ³B/sub u/ state, both d functions and higher excitations raise the predicted T/sub e/ value by perhaps as much as 5 000 cm^-1. For the ³B/sub g/ state, d functions raise the predicted excitation energy but higher excitations have the opposite effect. It is concluded that the excitation energy of the ³B/sub u/ state is dramatically increased by correlation effects, while T/sub e/ for the ³A/sub u/ and ³B/sub g/ states is markedly decreased by correlation

[en] Ab initio multiconfiguration self-consistent field (MCSCF) and configuration interaction (CI) calculations have yielded an activation energy of 80.9 +- 3.0 kcal/mol for the dissociation of formaldehyde to H₂ and CO on the ground state potential energy surface. The error limits are estimates based on an analysis of the effects of one-particle basis set, electron correlation, and transition state structure on the activation energy. Accurate structures and harmonic frequencies are presented for H₂CO (X ¹A₁) and the transition state

[en] Studies of the 1,2 hydrogen shift in carbenes, nitrenes, and vinylidenes are reviewed. The key role of this isomerization in these unstable intermediates in organic reactions is elucidated. Isomerization possibilities of the as yet unidentified H₂CN⁺ in the formation of HCN and HNC in interstellar space is discussed. The photodissociation of formaldehyde is explained on the basis of an unstable intermediate, hydroxycarbene. 94 references are cited