Dear Qin Dai I think that Yurii V Geletii is absolutely right. 😎 However, don't let this answer confuse you. He is just saying that 1-nonanol is quite air-stable and doesn't get oxidized significantly just by atmospheric oxygen and in the absence of a catalyst.

Dear Qin Dai no, to my knowledge the oxidation of nonanol to nonanal with oxygen without the use of any catalyst is not possible. This would mean that nonanol is not stable in air and would oxidize over time. As far as I know you always need a catalyst for this selective oxidation reaction, e.g. palladium compounds. Please see for example that attached reference entitled "Nanocrystalline Magnesium Oxide Stabilized Palladium(0):

An Efficient Reusable Catalyst for Room Temperature Selective

Aerobic Oxidation of Alcohols" and the references cited therein. In this article the oxidation of nonanol to nonanal is explicitly mentioned.

Dear Qin Dai, I agree with Frank about a non-catalytic O2 oxidation at ambient temperature. However, have you considered another approach?

In the oxo-alcohols processes that convert olefins through aldehydes to alcohols, the step from aldehydes to alcohols is a catalyzed hydrogenation. The industrial processes are used for a relatively wide range of olefin/aldehyde/alcohol molecular weights that span the C9 range. Catalysts that hydrogenate the C9 aldehyde (nonalal) to the C9 alcohol (nonanol) may also be effective for the reverse dehydrogenation with a suitable adjustment to operating conditions. ICI used to operate a process in the correct molecular weight range using a Cu based heterogeneous hydrogenation catalyst followed by a Ni-based polishing heterogeneous hydrogenation catalyst. Other process operators used similar catalyst systems. Therefore, similar Cu and/or Ni based catalysts may be effective for the reverse dehydogenation. Process conditions were at elevated temperature (I recollect 200 - 300oC) and pressure, but lower pressure would favour the dehydrogenation reaction.

My knowledge of this area is rather out of date. Therefore, there may be more recent practice and literature for the hydrogenation reaction that can help you with the reverse.

My best regards - Peter

Surely yes! Take a container with a large headspace, purge it with O2 and wait for several years (might be for 10 years) You will get a little of nonanal with a very low selectivity. Please, carry out this experiment and tell us the results.

Dear Qin Dai I think that Yurii V Geletii is absolutely right. 😎 However, don't let this answer confuse you. He is just saying that 1-nonanol is quite air-stable and doesn't get oxidized significantly just by atmospheric oxygen and in the absence of a catalyst.