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Carbon-hydrogen cr bonds

Carbon-carbon a bonds form by overlap of sp orbitals on adjacent atoms, and carbon-hydrogen cr bonds form by overlap of sp orbitals with hydrogen fs orbitals. [Pg.306]

Explain the dramatic decrease in acidity of the boldfaced "terminal" hydrogen atom in the following series of hydrocarbons. (Hint Consider the difference in the nature of the respective carbon-hydrogen cr-bonds and the anticipated relative stabilities of the anions resulting from deprotonation.)... [Pg.418]

Conjugated polymers differ from saturated polymers in that each carbon of the main chain is bonded to only three other atoms. The classic example is polyacetylene, (CH) , in which each carbon is cr-bonded to only two neighboring carbons and one hydrogen atom. The chemical structures of polyacetylene and some of the other most commonly studied conjugated polymers are shown in Fig. [Pg.99]

We can now completely specify the orbitals used to form the bonds in the ethylene molecule. As shown in Fig. 14.13, the carbon atoms are described as using sp hybrid orbitals to form the cr bonds to the hydrogen atoms and to each other and using p orbitals to form the tt bond with each other. Note that we have accounted fully for the Lewis structure of ethylene with its carbon-carbon double bond and carbon-hydrogen single bonds. [Pg.665]

A hydrogen atom is transferred from the metal to one of the alkene carbon atoms, forming a partially reduced intermediate with a C-H bond and carbon-metal cr bond. [Pg.278]

Among several propargylic derivatives, the propargylic carbonates 3 were found to be the most reactive and they have been used most extensively because of their high reactivity[2,2a]. The allenylpalladium methoxide 4, formed as an intermediate in catalytic reactions of the methyl propargylic carbonate 3, undergoes two types of transformations. One is substitution of cr-bonded Pd. which proceeds by either insertion or transmetallation. The insertion of an alkene, for example, into the Pd—C cr-bond and elimination of/i-hydrogen affords the allenyl compound 5 (1.2,4-triene). Alkene and CO insertions are typical. The substitution of Pd methoxide with hard carbon nucleophiles or terminal alkynes in the presence of Cul takes place via transmetallation to yield the allenyl compound 6. By these reactions, various allenyl derivatives can be prepared. [Pg.453]

As portrayed m Figure 2 20 the two carbons of acetylene are connected to each other by a 2sp-2sp cr bond and each is attached to a hydrogen substituent by a 2sp-ls CT bond The unhybndized 2p orbitals on one carbon overlap with their counterparts on the other to form two rr bonds The carbon-carbon triple bond m acetylene is viewed as a multiple bond of the ct + rr + rr type... [Pg.92]

Each carbon in propane is bonded to four atoms and is -hybridized. The C—C bonds are cr bonds involving overlap of a half-filled sp hybrid orbital of one carbon with a half-filled sp hybrid orbital of the other. The C—H bonds are cr bonds involving overlap of a half-filled sp hybrid oribital of carbon with a half-filled hydrogen orbital. [Pg.1202]

We know from Section 1.5 that cr bonds are cylindrically symmetrical. In other words, the intersection of a plane cutting through a carbon-carbon singlebond orbital looks like a circle. Because of this cjdindrical symmetry rotation is possible around carbon-carbon bonds in open-chain molecules. In ethane, for instance, rotation around the C-C bond occurs freely, constantly changing the spatial relationships between the hydrogens on one carbon and those on the other (Figure 3.5),... [Pg.93]

At this stage, it looks as though electron promotion should result in two different types of bonds in methane, one bond from the overlap of a hydrogen ls-orbital and a carbon 2s-orbital, and three more bonds from the overlap of hydrogen Is-orbitals with each of the three carbon 2/ -orbitals. The overlap with the 2p-orbitals should result in three cr-bonds at 90° to one another. However, this arrangement is inconsistent with the known tetrahedral structure of methane with four equivalent bonds. [Pg.232]

FIGURE 3.14 Each C H bond in methane is formed by the pairing of an electron in a hydrogen U-orbital and an electron in one of the four sp hybrid orbitals of carbon. Therefore, valence-bond theory predicts four equivalent cr-bonds in a tetrahedral arrangement, which is consistent with experimental results. [Pg.233]

Figure 6.38. Potential energy diagram for the hydrogenation of ethylene to the ethyl (C2H5) intermediate on a palladium(m) surface. The zero of energy has been set at that of an adsorbed H atom, (a) Situation at low coverage ethylene adsorbed in the relatively stable di-cr bonded mode, in which the two carbon atoms bind to two metal atoms. In the three-centered transition state, hydrogen and carbon bind to the same metal atom, which leads to a considerable increase in the energy... Figure 6.38. Potential energy diagram for the hydrogenation of ethylene to the ethyl (C2H5) intermediate on a palladium(m) surface. The zero of energy has been set at that of an adsorbed H atom, (a) Situation at low coverage ethylene adsorbed in the relatively stable di-cr bonded mode, in which the two carbon atoms bind to two metal atoms. In the three-centered transition state, hydrogen and carbon bind to the same metal atom, which leads to a considerable increase in the energy...
We have already explained. In terms of hybridisation, how a carbon atom can form four sp hybrid orbitals (see p. 47). We can apply this concept to explain the bonding in alkanes. Ethane is taken as an example of a typical alkane. The four sp hybrid orbitals on each carbon atom will overlap end-on with four other orbitals three hydrogen Is orbitals and one sp hybrid orbital on the other carbon atom. Four cr bonds will be formed and they will adopt a tetrahedral arrangement. This is illustrated for ethane in the diagram. [Pg.49]

Conformational isomerism in propane Propane is a three-carbon- (sp -hybridized) atom-containing linear alkane. All are tetrahedrally arranged. When a hydrogen atom of ethane is replaced by a methyl (CH3) group, we have propane. There is rotation about two C-C cr bonds. [Pg.38]

Alkynes are hydrocarbons that contain a carbon-carbon triple bond. A triple bond consists of a cr bond and two tt bonds. The general formula for the alkynes is C li2n-2- The triple bond possesses two elements of unsaturation. Alkynes are commonly named as substituted acetylenes. Compounds with triple bonds at the end of a molecule are called terminal alkynes. Terminal —CH groups are called acetylenic hydrogens. If the triple bond has two alkyl groups on both sides, it is called an internal alkyne. [Pg.108]


See other pages where Carbon-hydrogen cr bonds is mentioned: [Pg.165]    [Pg.167]    [Pg.1108]    [Pg.427]    [Pg.165]    [Pg.167]    [Pg.1108]    [Pg.427]    [Pg.146]    [Pg.153]    [Pg.225]    [Pg.99]    [Pg.71]    [Pg.907]    [Pg.880]    [Pg.126]    [Pg.91]    [Pg.917]    [Pg.917]    [Pg.152]    [Pg.236]    [Pg.196]    [Pg.1012]    [Pg.6]    [Pg.530]    [Pg.264]    [Pg.702]    [Pg.79]    [Pg.151]    [Pg.405]    [Pg.263]    [Pg.137]    [Pg.168]    [Pg.183]    [Pg.25]    [Pg.27]   
See also in sourсe #XX -- [ Pg.167 ]




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Carbon-hydrogen bonds

Cr-bonding

Hydrogen, [crs-

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