Hybridization carbon compound

In addition to compounds with planar, sp2-hybridized carbons, compounds with tetrahedral, sp3-hybridized atoms can also be prochiral. An vp3-hybridizec) atom is said to be a prochirality center if, by changing one of its attached groups, it becomes a chirality center. The —GH2OH carbon atom of ethanol, for instance, is a prochirality center because changing one of its attached -H atoms converts it into a chirality center. 

Unlike elimination and nucleophilic substitution reactions, formation of organo-lithium compounds does not require that the halogen be bonded to s/r -hybridized carbon. Compounds such as vinyl halides and aryl halides, in which the halogen is bonded to sp2-hybridized carbon, react in the same way as alkyl halides, but at somewhat slower rates. 

Notice that all the examples m Table 8 1 involve alkyl halides, that is compounds m which the halogen is attached to an sp hybridized carbon Alkenyl halides and aryl halides, compounds m which the halogen is attached to sp hybridized carbons are essentially unreactive under these conditions and the principles to be developed m this chapter do not apply to them... 

These are subdivided into (a) compounds isomeric with aromatic compounds in which the ring contains two double bonds but also an hybridized carbon (7 systems Scheme 6) or a quaternary nitrogen atom (9 systems Scheme 7). 

Scheme 6 Isomers of aromatic compounds with an ip -hybridized carbon atom...

Vicinal diol (Section 15.5) Compound that has two hydroxyl (—OH) groups on adjacent -hybridized carbons. 

The valence-bond concept of orbital hybridization described in the previous four sections is not limited to carbon compounds. Covalent bonds formed by-other elements can also be described using hybrid orbitals. Look, for instance, at the nitrogen atom in methylamine, CH3NH2, an organic derivative of ammonia (NH3) and the substance responsible for the odor of rotting fish. 

X-ray diffraction confirms linear coordination in Au(PPh3)(C=CC6F5) and Au(H2NCHMe2)(C=CPh) with the short Au-C bonds (1.935-1.99 A) expected for bonds to sp hybridized carbon. Decomposition of these compounds in the vapour above 150°C is a potential route to very pure gold films [162],... 

C-coupling is of outstanding importance in the azo coupling reaction for the synthesis of azo dyes and pigments. An aromatic or heteroaromatic diazonium ion reacts with the so-called coupling component, which can be an aromatic primary, secondary, or tertiary amine, a phenol, an enol of an open-chain, aromatic, or heteroaromatic carbonyl compound, or an activated methylene compound. These reactions at an sp2-hybridized carbon atom will be discussed in Chapter 12. In the... 

On the other hand, the rate constant k does not depend on the changing steric influence of substitutents in the 8-position, but correlates surprisingly well with the Hammett-Brown constant cr. This result indicates that the formation of an sp3-hybridized carbon atom (at the 1-position of the o-complex) leads to a compound without significant steric interaction of the electrophile with substituents in the 8-position. The o-complex cannot be planar and is asymmetric. The preferred conformation of a o-complex of this type is illustrated in Figure 12-6. The pseudoax-ial position of the electrophile E reduces the steric interaction between this group and the peri substituent R. 

H2—He at 8.5 5. This ion is an example of a homoaromatic compound, which may be defined as a compound that contains one or more sp -hybridized carbon atoms in an otherwise conjugated cycle. °... 

We may now proceed to an analysis of the significance of the d values. If the transition state were close to the product, then the P values of the disubstituted ethylenes should be small, because in the product, the substituent is bonded to an sp hybridized carbon atom. Thus, it is incapable of resonance interaction. As the observed values of p for the trans-disubstituted dienophiles are very large, we conclude that the transition state is closer to reactants than to products. The cis-disubstituted dienophiles show a much smaller value of P than do the trans compounds. It therefore seems likely that the transition state for the CIS compounds will be closer to product than is the transition state for the trans compounds. The values of p for the reaction of the tnws-disubstituted dienophiles with 9,10-dimethylanthracene, while large, are much smaller than... 

Although no 73Ge NMR spectra of stable doubly bonded germanium compounds have been recorded, NMR chemical shift data for the heteroatom of the double bond are available these are listed in Table II. The chemical shift of the, sp2-hybridized carbon atom of dimesitylneopentylger-mene (entry 1, Table II), without any polar substituents, falls at 8 124.2.26 The chemical shifts of the boron-substituted sp2-hybridized carbon atoms of two stable germenes (entry 2, Table II) fall in the upfield region of the... 

The hybridization concept which has been accepted for carbon compounds should not be applied to... 

Tablel3.1 Carbon-Carbon Single Bond Lengths and Hybridization State Compound Hybridization State Bond Length (A)...

It is obvious that these compounds have in common an uninterrupted cyclic arrangement of cross-conjugated jr-systems. Compound 5 likewise contains the maximum number of exocyclic double bonds at a perimeter consisting only of sp2-hybridized carbon atoms. Thus, our definition allows one to call it a radialene, i.e. naphtharadialene on the other hand, it excludes hydrocarbons such as 6 [3,4,5,6-tetrakis(methylene)cyclohexene]. Although in the latter molecule all carbon atoms are indeed sp2-hybridized, the number of exocyclic double bonds has not reached its maximum. In 5, however, the number of double bonds cannot be increased further. 

We are aware that these simple rules must and will be extended as the structural complexity of the known radialenes evolves. Unfortunately, however, the catchiness of the term radialene has led to its inflationary use in recent years. Although we think it is justified to call molecules such as 11 and 12 expanded [4]- (n = 1) and [6]radi-alenes (n = 3) — by widening our above definition, since sp-hybridized carbon atoms are allowed —we hesitate to call compounds of the type 13 heteroradialenes. 

Since nucleophilic addition to a metal-coordinated alkene generates a cr-metal species bonded to an -hybridized carbon, facile 3-H elimination may then ensue. An important example of pertinence to this mechanism is the Wacker reaction, in which alkenes are converted into carbonyl compounds by the oxidative addition of water (Equation (108)), typically in the presence of a Pd(n) catalyst and a stoichiometric reoxidant.399 When an alcohol is employed as the nucleophile instead, the reaction produces a vinyl or allylic ether as the product, thus accomplishing an etherification process. 

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