2nd Organic chemistry xperiment.docx

This delocalisation is no means complete but it have

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ring electron system. This delocalisation is no means complete, but it have a significant effect on the properties of both the carbon-chlorine bond and the polarity of the molecule.The delocalisation introduces some extra bonding between the carbon and the chlorine, making the bond stronger. This has a major effect on the reactions of compounds like chlorobenzene. There is also some movement of electrons away from the chlorine towards the ring. Chlorine is quite electronegative and usually draws electrons in the carbon-chlorine bond towards itself. In this case, this is offset to some extent by the movement of electrons back towards the ring in the delocalisation. The molecule is less polar than you would otherwise have expected. Then, the aryl halides are also insoluble in water. They are denser than water and form a separate lower
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layer. The molecules of aryl halide are quite large compared with a water molecule. In order for chlorobenzene to dissolve it would have to break lots of existing hydrogen bonds between water molecules the strong van der Waals dispersion forces between chlorobenzene molecules had to be broken down which cost energy. The only new forces between the chlorobenzene and the water would be van der Waals dispersion forces which not as strong as hydrogen bonds (or the original dispersion forces in the chlorobenzene), and so not much energy released while it formed.The example of halogenoarenes used in experiment is chlorobenzene. This is because Chlorine is quite electronegative and usually draws electrons in the carbon-chlorine bond towards itself. In this case, this is offset to some extent by the movement of electrons back towards the ring in the delocalisation. The molecule is less polar than others. In chemistry, there are many types of reaction. One type of reaction in organic chemistry is substitution reaction. A substitution reaction is a reaction in which one atom in a compound is replaced with another atom. This type of reaction is usually seen in alkyl halides. An alkyl halide (haloalkane) is a compound in which the hydrogen of an alkane is replaced by a halogen atom such as fluorine and chlorine. Alkyl halides usually go through substitution reaction because it can leave with its bonding pair of electrons to form a stable halide ion. One type of substitution reaction is a nucleophilic substitution. In this reaction, a nucleophile replaces a leaving group from a carbon atom. Moreover, nucleophilic substitutions have can occur in two mechanisms: S N 1 (First-order nucleophilic substitution) and S N 2 (Second- order nucleophilic substitution). In an S N 1 reaction, the C-X bond is broken first before the nucleophile approaches while in an S N 2 reaction, the nucleophile and the electrophile collide. The rate of S N 1 reactions is determined by the slow step, in which the bond between the carbon and the leaving group is ionized to form a carbocation. Many factors affect S N 1 and S N 2. These factors include the type of electrophile, the strength of the nucleophile, and the type of solvent. Because carbocation stability increases from primary to secondary to tertiary alkyl halides, tertiary alkyl halides favor S N 1 reactions. On the
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