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foxy2
(Distinctive Doe) 09-08-01 04:23 No 211334 |
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Route to interesting aldehydes | Bookmark | |||||
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_softwar Do Your Part To Win The War |
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Rhodium (Chief Bee) 09-08-01 04:54 No 211343 |
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Re: Route to interesting aldehydes | Bookmark | |||||
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. |
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foxy2 (Distinctive Doe) 09-08-01 04:59 No 211345 |
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And we have this variation | Bookmark | |||||
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 Do Your Part To Win The War |
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Rhodium (Chief Bee) 09-08-01 05:03 No 211347 |
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Re: And we have this variation | Bookmark | |||||
Note: The Reimer-tiemann formylation only works on phenols and anilines, not methoxybenzenes. |
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Karl (Stranger) 09-08-01 21:34 No 211543 |
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Re: And we have this variation | Bookmark | |||||
It gives very good yields on 4-methoxyphenol ~70% |
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Rhodium (Chief Bee) 09-09-01 04:27 No 211573 |
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Re: And we have this variation | Bookmark | |||||
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. |
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Antoncho (Official Hive Translator) 09-09-01 12:09 No 211629 |
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Re: And we have this variation | Bookmark | |||||
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 |
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Rhodium (Chief Bee) 09-09-01 12:16 No 211631 |
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Re: And we have this variation | Bookmark | |||||
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. |
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foxy2 (Distinctive Doe) 09-09-01 15:59 No 211684 |
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Re: And we have this variation | Bookmark | |||||
Antoncho Maybe the method in Post 211323 (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. Do Your Part To Win The War |
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Karl (Stranger) 09-09-01 16:23 No 211690 |
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Re: And we have this variation | Bookmark | |||||
Sure, its very simple, will give a full write up |
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Karl (Newbee) 09-18-01 03:56 No 214710 |
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2-Hydroxy-5-methoxybenzaldehyde | Bookmark | |||||
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. |
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Rhodium (Chief Bee) 09-18-01 04:22 No 214721 |
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Re: 2-Hydroxy-5-methoxybenzaldehyde | Bookmark | |||||
Thank you! |
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Karl (Newbee) 09-18-01 13:24 No 214870 |
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Re: 2-Hydroxy-5-methoxybenzaldehyde | Bookmark | |||||
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? |
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Karl (Newbee) 09-18-01 13:31 No 214875 |
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Re: 2-Hydroxy-5-methoxybenzaldehyde | Bookmark | |||||
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; |
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halfapint (Ubiquitous Precursor Medal Winner) 09-18-01 16:08 No 214929 |
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Re: 2-Hydroxy-5-methoxybenzaldehyde | Bookmark | |||||
& 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. turning science fact into <<science fiction>> |
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