Bond, chemical triple

There are also carbon-carbon triple bonds. Acetylene (or, more rigorously, ethyne—yne indicating the presence of a triple bond in the molecule), C2H2, is a common hydrocarbon that contains a triple bond HC=CH. Note that here too each carbon atom makes four chemical bonds the triple bond counts as three. Acetylene finds significant commercial use in oxyacetylene torches. 

It is not possible to assess the ratio of carbon carbon double bonds (polycumulene)/triple bonds (polyyne) in the film solely by Raman spectroscopy. Theoretically the quantum-chemical simulation shows that both isomers have very similar Raman spectra [39]. 

The hrst half of this chapter reviews the Lewis model of chemical bonding and the procedures for writing structural formulas of chemical compounds, especially organic ones. The second half discusses bonding in terms of the wave nature of electrons and concludes with its application to compounds that contain carbon-carbon single bonds, double bonds, and triple bonds. 

Fig. 65 Magnification of two regions in the DRIFT spectra of Kapton presented in Fig. 62. a Region of C-H stretching vibrations at 3080 cm-1 aromatic hydrocarbons at 2950 cm 1 aliphatic hydrocarbons. The baseline applied for the peak area calculation is shown as a dotted line in the spectrum for 31,500 pulses, b Region of conjugated double bonds and triple bonds at 2270 cm 1 the -N=C=0 stretching vibration at 2255 cm 1 the -C=C- stretching vibration and at 2230 cm-1 the -C=N stretching vibration. Around 2350 cm 1 the typical doublet of gas-phase C02 is present. REPRINTED WITH PERMISSION OF [Ref. 135], COPYRIGHT (2000) American Chemical Society...

Bond energies are always positive, because it always takes energy to break a bond. We say that the HCl bond is stronger than the CI2 bond because it requires more energy to break it. In general, compounds with stronger bonds tend to be more chemically stable, and therefore less chemically reactive, than compounds with weaker bonds. The triple bond in N2 has a bond energy of 946 kJ/mol. 

How does each of the three major bonding theories (the Lewis model, valence bond theory, and molecular orbital theory) define a single chemical bond A double bond A triple bond How are these definitions similar How are they... 

The nine chemically sensible resonance structures for a double bond are shown in Scheme 1. A straight line represents a covalent bond (i.e., one electron in an M-centered AO-like MO and one electron in the E-centered counterpart), an arrow pointing towards M represents a dative bond (both electrons on the E-centered AO-like MO) and an arrow pointing towards E is a back-bond (i.e., both electrons on the M-centered AO-like MO). The bottom line (or arrow) describes the cr-bond and the upper line describes the n component of the ME bond. A triple bond can be described in a similar manner, with two sets of 7T bonds.Note that the nine resonance structures shown in Scheme 1 are less than half of the 20 configurations generated from the MCSCF(4,4) wavefunction. The remaining contributions correspond to less sensible arrangements, such as much weaker one- or three-electron bonds. 

An enhancement of the simple substructure approach is the Fragment Reduced to an Environment that is Limited (FREL) method introduced by Dubois et al. [7] With the FREL method several centers of the molecule are described, including their chemical environment. By taking the elements H, C, N, O, and halogens into account and combining all bond types (single, double, triple, aromatic), the authors found descriptors for 43 different FREL centers that can be used to characterize a molecule. 

Molecules with chirality centers are very common both as naturally occurring sub stances and as the products of chemical synthesis (Carbons that are part of a double bond or a triple bond can t be chirality centers)... 

Acetylenic hydrogens are unusual in that they are more shielded than we would expect for protons bonded to sp hybridized carbon This is because the rr electrons circulate around the triple bond not along it (Figure 13 9a) Therefore the induced magnetic field is parallel to the long axis of the triple bond and shields the acetylenic proton (Figure 13 9b) Acetylenic protons typically have chemical shifts near 8 2 5... 

Rea.ctlons, Propargyl alcohol has three reactive sites—a primary hydroxyl group, a triple bond, and an acetylenic hydrogen—making it an extremely versatile chemical intermediate. 

Carbon has six electrons around the atomic core as shown in Fig. 2. Among them two electrons are in the K-shell being the closest position from the centre of atom, and the residual four electrons in the L-shell. TTie former is the Is state and the latter are divided into two states, 2s and 2p. The chemical bonding between neighbouring carbon atoms is undertaken by the L-shell electrons. Three types of chemical bonds in carbon are single bond contributed from one 2s electron and three 2p electrons to be cited as sp bonding, double bond as sp and triple bond as sp from the hybridised atomic-orbital model. 

Analysis of the NMR chemical shifts of the triple bond carbon atoms of the substituted ynamines and comparison of these data with the corresponding values for compounds of the ethylene series suggest the presence of counterpolarization... 

The deoxyuric acids were early formulated with a cyclic triple bond (138) but recent chemical e ddcnce and ultraviolet spectral data have led to their reformulation as 139 or 140. Although the results of the early investigations of the structure of uric acid using chemical methods were interpreted in favor of structure 141i5s-i6g structure was considered to be supported by its ultraviolet spec-... 

One of the most important publications on this subject, considered frorn the chemical side, is that of Gertrude Woker. This investigator drew attention to the importance of multiple bonding. The double bond is often accompanied by a pleasant, but the triple or acetylenic linkage generally produces a disagreeable smell a multiplicity of double bond can produce an effect equivalent to a triple bond. 

Physical properties of alkynes [49, p. 251] are essentially similar to those of alkanes and alkenes. These compounds are weakly polar and are insoluble in water, but they are quite soluble in organic solvents of low polarity (e.g., ether, benzene, CCl ). Chemically, alkynes are more reactive than alkanes but behave like alkenes. The triple bond appears to be less reactive than the double bond in some reagents while more reactive in others. In a chemical reaction, the triple bond is usually broken into a double bond, which may eventually split into single bonds. 

In chemistry, the formula of an acyclic compound with no multiple bonds corresponds in an obvious way to a tree having different kinds of vertices (corresponding to the different atoms). If double or triple bonds are present, they are best regarded as different kinds of edges, and the formula is still represented as a tree. Figure 3 shows a graphical tree, and the formula of a chemical compound having its structure. 

Alkenes, alkynes, and arenes (aromatic compounds) all contain carbon-carbon multiple bonds. Alkenes have a double bond, alkynes have a triple bond, and cneues have alternating double and single bonds in a six-membered ring of carbon atoms. Because of their structural similarities, these compounds also have chemical similarities. 

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