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Boffis
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@clearly_not_atara, There is some interesting chemistry in those papers but the problem I see is the sodamide in liquid ammonia first step. How many
amateurs are set up to handle such stuff? Sodamide is not great stuff at the bet of times. Liquid ammonia requires pretty sophisticated equipment to
handle it safely.
For most amateurs too, the diazonium route from an aniline to a nitro compound may be easier as sodium nitrite is easier to get than performic acid.
Once nitrated the o- chlorine is sufficiently reactive to be displaced by an amine group using fused urea, or a methoxy group with sodium
methoxide/methanol.
Has anyone tried copper catalysed reactions with fused p-DCB?
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clearly_not_atara
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I guess I think it's moderately surprising that you're objecting to sodamide (which is pretty nasty) but you're suggesting a Sandmeyer over performic.
Performic oxidations are one of the most common amateur oxidation techniques, while Sandmeyer is a big foamy mess and it can go boom.
Anyway, the goal is to get a 1,4-result rather than a 1,2,4, and avoid the vigorous nitration conditions.
And so, the copper-catalyzed SNAr of aryl iodides and bromides with the nitrite anion is another possibility:
1: https://pubs.acs.org/doi/abs/10.1021/acs.joc.4c00463 (uses an oxamide ligand with NaNO2)
2: Paik and Jung, attached, uses a diamine ligand with t-butyl nitrite
This displacement is also mentioned in the PhD thesis "Copper-Assisted Nucleophilic Substitution Reactions of Aryl Halides" by JA Copeland, U
Manchester, 1979.
This rxn would have to follow the transhalogenation I mentioned before, but since you only need one transhalogenation instead of two, you get
potentially a much nicer overall process.
Attachment: paik2012.pdf (302kB)
This file has been downloaded 80 times
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Boffis
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Thanks for the links C-not-A, I had a good long read. But I don't see any mention of aryl chlorides being used as a substrate, rather bromo and
iodo-aryls and since this thread is about derivatives of p-dichlorobenzene that's an issue.
Going back to the sodamide route you referred to in an earlier post, do you think you could use a liquid primary amine such as butylamine or
cyclohexylamine as the solvent. Ethylamine dissolve lithium so maybe you could use this as a solvent though it boils at a rather low temperature,
about 16-18 C if I reall correctly. That said, if ethylamine would work why not oe of the amines I mentioned? They would also allow the reaction to
proceed at a higher temperature too.
Actually thinking about this; the main product will probably end up being an N-alkyl substituted chloroaniline. If you are using a preformed sodamide,
could you use say trimethylamine or triethylamine as the solvent?
[Edited on 13-8-2024 by Boffis]
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clearly_not_atara
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If we are innovating the method, then there is always the possibility of something like sodium diisopropylamide, NaNO2, DMF. In fact this is the first
report I have heard of using sodamide to make any benzyne, usually I see lithium diisopropylamide, organometallics, or KNH2. So I definitely wanted to
post the paper just for that reason.
Sodamide still has a relatively poor solubility in most solvents, probably including trimethylamine (which has a pronounced dead-fish smell). Lithium
amide is more soluble but is a weaker base.
There are reports of making sodium diisopropylamide by the direct combination of metallic sodium with diisopropylamine using an "electron transfer
catalyst" for which isoprene was suggested and maybe limonene or other monoterpenes would work. This seems like one of the mildest routes to any
alkali metal amide because diisopropylamine has a relatively low volatility and can be dried under reasonable conditions.
For the copper-catalyzed route, I had imagined that it would follow a halogen exchange with NiBr2 or NiI2 giving para-iodochlorobenzene or similar.
But this is also an extra step. Supposedly nickel iodide is more easily dried than other nickel halides, but the halogen exchange is difficult because
the thermodynamics favors the chloroarene. I would expect a low conversion followed by distillation to separate para-IPhCl from unreacted para-ClPhCl,
and here the use of iodine favors an easier separation.
Still very much at the "spitballing" stage but the opportunity is there IMHO.
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