I have a question about the following Halogenation reaction:

octane + chlorine gas -> ?

The question is what are the possible products of this reaction, and which product would be produced in the greatest quantity. I initially thought that a substitution would occur, resulting in HCl and 1-Chlorooctane.

This is wrong, apparently I think that this reaction would form several structural isomers, but I am wondering what isomer this reaction would form in the greatest quantity. Would 2-Chlorooctane, for example, be more prevalent than 1-Chlorooctane? If so, why?


Free radical substitution will likely occur as it’s the only way an alkane can be halogenated. I think that 1-chlorooctane will be produced as the major product. In my answer refer to the image attached for the structure of 1-chlorooctane (for simplicity’s sake I only drew the hydrogen atoms relevant to this question). enter image description here

To form 1-chloropropane, one of the 6 H1 atoms will have to be substituted whereas to form 2-chloropropane, one of the 4 H2 atoms will have to be substituted. So, don't you think that the chance that a H1 atom will substituted is greater than that of a H2 atom, due to the fact that there are more H1 atoms. Hence, accordingly, don’t you think that the chance to form 1-chloropropane is greater than that of 2-chloropopane. As a result, I think it is quite obvious that the quantity of 1-chloropropane will be greater than that of 2-chloropropane. Picture a box with 100 red marbles and 50 blue marbles in your mind. Isn't it quite logical to say that if 10 people were asked to grab a marble from inside the box without looking at the box's contents, more would grab red marbles than blue marbles?

  • $\begingroup$ Thank you for your help. Although it turns out the reason why I was wrong wasn't because of the isomer I said formed in the greatest quantity, but because of the fact that there was no catalyst above the arrow indicating a reaction, so no reaction would take place. $\endgroup$ – zachery moïse Feb 16 at 13:53
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    $\begingroup$ Firstly, this structure is neither octane nor propane. Secondly, this isn't a debate: please just state facts instead of asking rhetorical questions like "don't you think that X", "I think it's quite obvious that X", or "isn't it logical that X". Thirdly, it's not fully logical, because the rates of hydrogen abstraction also matter, not just the statistical factors stated. $\endgroup$ – orthocresol Feb 16 at 14:44
  • $\begingroup$ @zacherymoïse, even if a catalyst was added, I think my logic would be applicable as 1-chloropropane would still be in greater quantity than 2-chloropropane due to the reasons I stated. $\endgroup$ – Rabbit Feb 19 at 15:05

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