Orbital hybridization alkyl halides

The carbon that bears the functional group is sp hybridized m alcohols and alkyl halides Figure 4 1 illustrates bonding m methanol The bond angles at carbon are approximately tetrahedral as is the C—O—H angle A similar orbital hybridization model applies to alkyl halides with the halogen connected to sp hybridized carbon by a ct bond Carbon-halogen bond distances m alkyl halides increase m the order C—F (140 pm) < C—Cl (179 pm) < C—Br (197 pm) < C—I (216 pm)... 

Carbocations contain sp hybridized orbitals and thus have planar structures. S 1 mechanisms proceed via a carbocation intermediate, so a nucleophile attack is equally possible from either side of the plane. Therefore, a pure, optically active alkyl halide undergoing an S 1 substitution reaction will generate a racemic mixture as a product, as shown in Figure 3-6. 

Terminal alkynes are weakly acidic. The alkyne hydrogen can he removed by s strong base 9uch ae Na NH.. to yield nn a<%tylide anipn An acetylide anion ads as a nucleophile and can displace a halide ion from a primary alkyl halide in a n alkylation reaction. Acetylide anions are more stable iJian either alkyl anions or vinylic anions because their m ative charge is in a hybrid orbital with 50% s character, allowing the charge to be doser to the nucleus. 

One of the simplest functional groups consists of a single halogen atom, which we take to be chlorine for illustrative purposes. The chlorine atom forms a a bond to a carbon atom by overlap of its 3p orbital with a hybridized orbital on the carbon. The hybridized orbital may be sp, sp, or sp depending on the bonding in the hydrocarbon frame. Alkyl halides form when mixtures of alkanes and halogens (except iodine) are heated or exposed to light. 

Cycloheptatrienyl bromide is an ionic compound because its cation is aromatic. The alkyl halide is not aromatic in the covalent form because it has an sp hybridized carbon, so it does not have an unintenupted ring of p orbital-bearing atoms. In the ionic form, however, the cycloheptatrienyl cation (also known as the tropylium cation) is aromatic because it is a planar cyclic ion, all the ring atoms are sp hybridized (which means that each ring atom has a p orbital), and it has three pairs of delocalized TT electrons. The stability associated with the aromatic cation causes the alkyl halide to exist in the ionic form. 

Vinyl halides do not undergo Sn2 reactions in part because of the percent i -character in the hybrid orbital of the carbon atom in the C-X bond. The higher percent i -character in the sp hybrid orbital of the vinyl halide compared to the sp hybrid orbital of the alkyl halide (33% vs. 25%) makes the bond shorter and stronger. 

Hunsdiecker reaction conversion of a carboxylic acid into an alkyl halide by heating a heavy metal salt of the carboxyhc acid with bromine or iodine, hybrid orbital an orbital formed by mixing (hybridizing) orbitals. 

Benzyl halides are also potent alkylators in Sn2 displacement reactions. It will be remembered that the Sn2 reaction proceeds via an sp hybridized transition state, leaving a p orbital bonded to the incoming and departing... 

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