Let me tell you that this is Generally an inverse relationship. Have in mind that As you increase the chain of an alcohol, the reactivity decreases. This is due to an increase in disorder and decrease in intermolecular attraction between molecules. On the other hand in a solution with ethanol, it might be easier for the attraction to happen between other ethanol molecules because the branching is relatively short, not much hindrance. So it might be difficult foranother nonanol to want to react due to free-rotation ofattached alkyl group. Hope this can help
