Author Topic: Route to interesting aldehydes  (Read 2692 times)

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foxy2

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Route to interesting aldehydes
« on: September 08, 2001, 04:23:00 AM »
Hmmm I wonder if this would work on hydroquinone, catechol, 1,2,3-trihydroxybenzene or 1,2,4-trihydroxybenzene???

Gatterman Aldehyde Synthesis




L. Gattermann, Ber. 31, 1149 (1898); Ann. 357, 313 (1907)
Adams, J. Am. Chem. Soc. 45, 2375 (1923); 46, 1518 (1924)
Karrer, Helv. Chim. Acta 2, 89 (1919). C. A. Thomas, Anhydrous Aluminum Chloride in Organic Chemistry, p 600 (New York, 1941)
Fieser and Fieser, Organic Chemistry (3rd unabridged edition, 1956), pp 678-679

Source

http://www.geocities.com/chempen_software/reactions/RXN076.htm









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Rhodium

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Re: Route to interesting aldehydes
« Reply #1 on: September 08, 2001, 04:54:00 AM »
Yes, this is a well-known method. A less dangerous variation (avoiding the use of cyanide gas) is to use Zn(CN)2 and HCl, which creates the HCN and ZnCl2 catalyst in situ.

foxy2

  • Guest
And we have this variation
« Reply #2 on: September 08, 2001, 04:59:00 AM »
Reimer-Tiemann Reaction.






F. Reimer and F. Tiemann, Ber. 9, 824, 1268, 1285 (1876)
H. Gilman, C. E. Arntzen and F. J. Webb, J. Org. Chem. 10, 374 (1945)
L. N. Ferguson, Chem. Revs. 38, 229 (1946)
Wynberg, Chern. Revs. 60, 169 (1960)

Cf. Ciamician-Dennstedt Rearrangement, Duff Reaction



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Rhodium

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Re: And we have this variation
« Reply #3 on: September 08, 2001, 05:03:00 AM »
Note: The Reimer-tiemann formylation only works on phenols and anilines, not methoxybenzenes.

Karl

  • Guest
Re: And we have this variation
« Reply #4 on: September 08, 2001, 09:34:00 PM »
It gives very good yields on 4-methoxyphenol ~70%

Rhodium

  • Guest
Re: And we have this variation
« Reply #5 on: September 09, 2001, 04:27:00 AM »
Yes, but that is a phenol too, I was referring to methoxy-substituted benzenes only, like 1,4-dimethoxybenzene.

Could we have a writeup of that 4-methoxyphenol procedure, Karl? I'm sure many people here would like it.

Antoncho

  • Guest
Re: And we have this variation
« Reply #6 on: September 09, 2001, 12:09:00 PM »
yes, yes, that'd bee very cool!

i have a question though: is there a way to make p-methoxyphenol w/out buyng it? ::)  
i mean like, you can methylate hydroquinone w/one equivalent of MeI and get some but that sucks as you'll end up w/a mixtr that is pretty hard to separate...
Or to brominate anisol and hydrolyse...bromine...yuck!

Also, is there any trivial name for p-MeOphenol and where is it used?

Antoncho

Rhodium

  • Guest
Re: And we have this variation
« Reply #7 on: September 09, 2001, 12:16:00 PM »
Perhaps 4-methoxyphenol and hydroquinone can be separated by steam distillation? A non-polar wash of the basic reaction mixture will remove any formed 1,4-dimethoxybenzene.

If only one equivalent of base was used in the methylation of hydroquinone, I belive chances are good to end up with 4-methoxyphenol as the main product, because without the deprotonation of the phenol group, the MeI alkylation would be very difficult.

foxy2

  • Guest
Re: And we have this variation
« Reply #8 on: September 09, 2001, 03:59:00 PM »
Antoncho
Maybe the method in

Post 211323 (missing)

(foxy2: "Phenol to hydroquinone", Chemistry Discourse)
will also work on methoxybenzene to yeild p-methoxy phenol?  Rhodium says its a messy reaction.  The references may yeild more clues. 

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Karl

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Re: And we have this variation
« Reply #9 on: September 09, 2001, 04:23:00 PM »
Sure, its very simple, will give a full write up

Karl

  • Guest
2-Hydroxy-5-methoxybenzaldehyde
« Reply #10 on: September 18, 2001, 03:56:00 AM »
Sorry I've been awhile...

Reimer-Tiemann formylation of 4-Methoxyphenol

Into a 2L three neck flask was placed 125g (1mol) 4-MP and a still hot solution of 320g (8mol) NaOH in 400ml H2O (Addition while hot helps the phenol to dissolve and avoid carbonate formation)
The flask was set with a reflux condenser,  dropping funnel and thermometer (using a Claison adaptor) and mechanical stirrer then heated to ~70'C on the oil bath. When this temperature had been reached Chloroform (160ml, 2mol) was added dropwise (and portionwise) over the course of 4hrs while maintaining the stirring and temperature,
over this time the rxn became a very dark brown with a yellow green froth and a heavy brown precipetate (The sodium phenolate product)

The rxn was allowed to stir for a further hour at the same temperature, allowed to cool and then transfered to a 5L flask with aid of some hot water and subsequently acidified with H2SO4 (150-200ml 10N). Acidification causes the product to rise to the top as a black oil.

The black oil was transfered into a flask with some clean water and steam distilled (collect ~5L distillate).
Quite a volume of black tar remains after this distillation.

The yellow oil in the distillate was extracted with DCM and evaporated to yield 112g (74%) 5-Methoxysalicylaldehyde, can be further purified by distillation under N2 (bp 133'/15mm).
Based on a procedure found in Org.React. vol28 p16

This material was sufficiently pure for methylation to 2,5-DiMeo-benzaldhyde and gave a 76% yield with DMS/NaOH(aq).


Note: the aim was to maintain the rxn temperature at 70'C but it did briefly over shoot to ~80'C in the early stages.
The alkali salts of this salicylaldehyde are quite prone to atmospheric oxidation.

 
 

Rhodium

  • Guest
Re: 2-Hydroxy-5-methoxybenzaldehyde
« Reply #11 on: September 18, 2001, 04:22:00 AM »
Thank you!

Karl

  • Guest
Re: 2-Hydroxy-5-methoxybenzaldehyde
« Reply #12 on: September 18, 2001, 01:24:00 PM »
What does ' ' mean?
Err...That sequence of letters at the foot of my post but won't display in a post when I write it...which has just disapeared?

Karl

  • Guest
Re: 2-Hydroxy-5-methoxybenzaldehyde
« Reply #13 on: September 18, 2001, 01:31:00 PM »
It doesn't appear in the search matches now although it did in several posts about a minute ago. ie 'and symbol' followed by nbsp;
 

halfapint

  • Guest
Re: 2-Hydroxy-5-methoxybenzaldehyde
« Reply #14 on: September 18, 2001, 04:08:00 PM »
& n b s p ;  (connect those letters and it won't show up) is HTML code for non-breaking space, used to put a displayable space into a document. Without it, an HTTP server will automatically strip out excess spaces, defined as more than one consecutive space between words, or anywhere else, and all spaces at the beginning of lines. This has raised havoc with the traditional teaching of writing style, which says to put a double space between sentences, after a period. Evidently those who defined the HTTP standards weren't grammarians.

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