weilawei
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TEMPO 2,2,6,6-Tetramethylpiperidine 1-oxyl
I ordered some TEMPO to experiment with oxidation of primary alcohols to aldehydes and carboxylic acids, but in order to get a reasonable price, I had
to order 100g ($147 shipped). I don't need all of that, so if anyone is interested, I'd be happy to share at cost, buyer pays shipping. This is a
fascinating catalyst, and I'm super excited to try it out and see what other members can come up with using it.
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Sidmadra
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Are you ordering it from China? If so that price seems 10x too high. Tempo is a common item so you should be able to get it $200-300/kg from China.
Figure that if you're going to sell what you have leftover, you may as well get a good deal?
If you do end up getting some, I may be interest in grabbing some later on.
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weilawei
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I'm getting it from a US supplier. I have no experience with negotiating custom orders from China. My experience with products from there is limited
to ordering off eBay. I've already placed the order (otherwise I'd look into ordering it from China) and received confirmation--I should have it
within the week.
As I said, I'm just looking to get rid of the excess, not to make anything off of it. Small amounts, larger amounts, today, tomorrow, or far in the
future--that's all fine by me. I'm in no rush. (It was bonus money from work anyway, so I treated myself.) What would be really cool is if we got a
bunch of people to try out different reactions with it and report on it.
Myself, I'm going to start simply with TEMPO/TCCA mediated oxidation of ethanol to ethanoic acid. I've got a small stack of papers here with all sorts
of neat reactions.
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Sidmadra
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Ahhh I see. About the TEMPO/TCCA reaction, isn't TCCA able to oxidize all the way to carboxylic acid on its own? I seem to remember TCCA being a
pretty potent oxidizer. I remember wanting to make acetaldehyde from ethanol and TCCA but never did because it would go all the way to the acid, or so
I thought.
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weilawei
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From "Trichloroisocyanuric/TEMPO Oxidation of Alcohols under Mild Conditions: A Close Investigation" by De Luca, et al.:
| Quote: | To clarify some mechanistic aspects of the oxidation, we have conducted some additional runs. The course of the oxidation does not change using
catalytic alkaline salts (NaBr, NaI, LiF) other than NaCl or using Bu4NBr. The use of only 1 equiv of TCCA causes a very slow reaction: in the case of
oxidation of benzyl alcohol, the reaction requires 15 h at 25 °C for completion. The reaction is very slow even when NCS (2 equiv) is used instead of
TCCA. The oxidation to carboxylic acid does not occur in the absence of water in the reaction mixture, and the reaction stops with the formation of
the aldehyde. The reaction can be conducted both in acetone and MeCN, under the reported experimental conditions, with the same identical results,
while only carbonyl compounds are formed using dry dichloromethane.11 Increasing the amount of water increased the formation of chlorinated products;
under these conditions, benzyl alcohol is oxidized slowly to a mixture of chlorosubstituted benzoic acids.
It is noteworthy that the oxidation of the intermediate aldehyde does not require TEMPO as catalyst. In fact, the aldehyde is rapidly oxidized to the
corresponding carboxylic acid by treatment with 1 equiv of TCCA in acetone/water, without addition of the catalyst. |
| Quote: | | (22) The hydrolysis of TCCA seems to be catalyzed by the presence of even catalytic amounts of halide ions; in the absence of traces of sodium
halides, no oxidation to carboxylic acids takes place. |
It looks like with TEMPO that you can select for either the aldehyde or the carboxylic acid by various parameters: temperature, reaction time, choice
of stoichiometric oxidant, use of phase transfer catalysts, etc..
| Quote: | | In 1987, Anelli et al. made a key contribution to TEMPO-mediated oxidations by showing that the very cheap reagent chlorine bleach (aqueous NaOCl) can
function very effectively as a stoichiometric oxidant for alcohols in the presence of traces of 4-MeO-TEMPO. 3 They established a protocol involving a
reaction run at 0 C in a biphasic CH2Cl2–water mixture in the presence of excess of NaOCl, NaHCO3, KBr, and catalytic 4-MeO-TEMPO for oxidation to
aldehydes. Under these conditions the oxidation to acids is quite slow. If the acid is desired, it is advisable to add a phase-transfer catalyst to
speed up the oxidation. |
[Edited on 20-3-2018 by weilawei]
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JJay
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I am interested in some TEMPO. I sent you a U2U.
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Melgar
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I have a bunch of excess elemental selenium and TBAB, among other things. I'm really not in much of a position to be doing chemistry (or even talking
about chemistry, really  ) but that's been one of the ones I've been trying to
get my hands on for a while, without much success. I'd prefer to trade something I have since I'm pretty much broke, but could possibly purchase a
small amount.
I'd even trade one of my more expensive reagents like LiAlH4, PdCl2, AgNO3.
The first step in the process of learning something is admitting that you don't know it already.
I'm givin' the spam shields max power at full warp, but they just dinna have the power! We're gonna have to evacuate to new forum software!
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weilawei
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Well, bad news is that fell through. I got a notice that it was no longer available, and my order was refunded. The search continues! I didn't want to
have to synthesize it, but that's looking like my best option. There is an old post around here with details, though.
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JJay
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I was thinking about trying... Metacelsus made some: https://www.sciencemadness.org/whisper/viewthread.php?tid=62...
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