Table of Contents
What is the selectivity ratio of chlorine?
This gives us a ratio of 55:15 , or 3.66. So for this reaction, the free radical chlorination of propane at 25°C, chlorine is 3.66 times more selective for secondary hydrogens than for primary hydrogens.
Why is chlorination more reactive than bromination?
Although the bromine nucleus is more positively charged than the chlorine nucleus, the increase in the radius and the extra shielding in the bromine atom outweigh this factor, which means that an electron is more easily attracted into the outer shell of a chlorine atom than that of a bromine atom, so chlorine is more …
Which chlorine has more selectivity bromine iodine?
Bromine radical is less reactive and more selective. In contrast, chlorine radical is more reactive and less selective in its reaction.
Which is faster chlorination or bromination?
Chlorination is faster than bromination because chlorine is more reactive.
Which is more reactive chlorine or bromine?
Why: Chlorine is more reactive the bromine because chlorine radical is less stable then bromine radical.
Which element is most selective in its halogenation?
The nature of the substrate determines the pathway. The facility of halogenation is influenced by the halogen. Fluorine and chlorine are more electrophilic and are more aggressive halogenating agents. Bromine is a weaker halogenating agent than both fluorine and chlorine, while iodine is the least reactive of them all.
Why chlorination is more reactive and less selective?
Chlorination is less selective than bromination because chlorination has smaller differences in activation energy for attack at 1°, 2°, and 3° positions. Consider the halogenation of propane at the 1° and 2° positions. Formation of the different halopropanes occurs during the chain propagation steps.
What are the two main difference between chlorination and bromination?
We’ll do the math in a second, but the key difference is that in chlorination, the key propagation step is exothermic and in bromination, the key propagation step is endothermic. This is because chlorination forms a strong H-Cl bond (103 kcal/mol) and bromination forms a much weaker H-Br bond (87 kcal/mol).
Which of the following reaction is most selective bromination of alkane chlorination of alkane?
Reason: Bromination of alkane is highly selective compared to chlorination reaction.
Is Cl or Br a better electrophile?
Being that Cl is more electronegative than Br, Cl is less willing to give up those electrons as compared to Br.
Why is bromine better leaving group than chlorine?
like you said Br- is bigger than Cl- and can therefore better stabilize the negative charge, making it a better leaving group.
Why does chlorine have a greater electron affinity than bromine?
On moving from chlorine to bromine to iodine, the electron affinity decreases (becomes less negative). This is because the increase in atomic size decrease the effective nuclear charge. Hence, the additional electron feels less attraction by the large atom.
Why is chlorine not selective?
Since chlorine is a rather reactive reagent, it shows relative low selectivity, that means Cl2 does not discriminate greatly among the different types of hydrogens atoms (primary, secondary or tertiary) in an alkane.
What is selectivity in halogenation?
Radical halogenation is selective for the most substituted C-H. More Substituted Radicals Are More. Stable (by Hyperconjugation)
What do you mean by reactivity and selectivity?
In chemistry the reactivity–selectivity principle or RSP states that a more reactive chemical compound or reactive intermediate is less selective in chemical reactions. In this context selectivity represents the ratio of reaction rates.
Is bromine less reactive than chlorine?
Because chlorine is more reactive than bromine, it displaces bromine from sodium bromide.
Why bromination of alkane is slower than chlorination?
Bromination of alkanes occurs by a similar mechanism, but is slower and more selective because a bromine atom is a less reactive hydrogen abstraction agent than a chlorine atom, as reflected by the higher bond energy of H-Cl than H-Br.
Is bromine or chlorine more reactive?
Because chlorine is more reactive than bromine, it displaces bromine from sodium bromide. The solution turns brown.
Is chloride or bromine the better leaving group?
To simply answer your question, it’s because bromide is bigger and more polarizable due to its size. Obviously, they have the same charge but the only difference is the size of the two. In addition, it’s bulkier make up makes it a much favorable leaving group.
Why is chlorination less selective than bromination?
Chlorination is less selective than bromination because chlorination has smaller differences in activation energy for attack at 1°, 2°, and 3° positions. Consider the halogenation of propane at the 1° and 2° positions.
Why can’t chlorination be used to prepare alkyl halides?
Because of the two major problems for chlorination, lack of selectivity and multi-substitution, chlorination is not useful as a synthesis method to prepare a specific alkyl halide product. Instead, bromination with Br 2 can be applied for that purpose. The relative lower reactivity of bromine makes it exhibits a much greater selectivity.
Why does bromine show greater selectivity than other hydrocarbons?
The relative lower reactivity of bromine makes it exhibits a much greater selectivity. Bromine is less reactive, means it reactive more slowly, therefore it has chance to differentiate between the different types of hydrogens, and selectively reacts with the most reactive one.
Why does bromination have the greatest utility synthesis of alkyl halide?
Therefore bromination usually occurs selectively on the most reactive position (the position that forms the most stable carbon radical intermediate), and gives one major product exclusively, as the example here for bromination of isobutane. As a result, bromination has the greatest utility synthesis of alkyl halide.