Question

From your experimental results, calculate the relative reactivity (rate) for abstraction of each type of hydrogen by a chlorine radical. (This is covered your lecture text.) my experimental results are below:) this is also a lab report over radical halogenation of 1-Chlorobutane. what does the reactivity tell us?

pt 2 1-Chlorobutane has two types of 2? hydrogens relative to the position of the chlorine atom in the molecule. Did you results show an equal amount of chlorination at each 2? site? Give a possible explanation for any difference observed in the amount of chlorination at each site.

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Answer 1

In the chlorination of 1-chlorobutane, we have four different H's which can be extracted during the free-radical chlorination process and Cl radical may be added to the posiitons.

They are, 1,4 position with respect to initial Cl. 1,3-position with respect to the initial Cl present, 1,2-position with respect to the Cl initially present at 1 position of chain and the 1,1 position which is on the same carbon atom that had the initial Cl in th substrate molecule. Cl exerts a -ve inductive effect, that is it exerts an electron withdrawing effect. This effect is least for the radical formed at the 3-position which makes it most stable and thus major product formed would be 1,3-dichlorobutane. This is then followed by 1,4-dichlorobutane, than 1,2-dichlorobutane and least of all is 1,1-dichlorobutane which is formed as the minor product in the chlorination reaction. (The integrations in the table are not clearly visible). But one may calculate the relative intensities, by %area under the curve/number of equivalent H's at that position. Say for 1,3-dichlorbutane the area under curve is 49% of total area of all the products, than relative reactivity will be 49/2 = 24.5. Adding all the relative rates and taking the percentage of each as relative reactivity rate/total relative reactivity rate would give an average relativity reactivity rate for each position and product formed. Overall the experiment tells us that 3-position is most reactive and 1-position is least reactive of all posible positions for chlorination of 1-chlorbutane.