foxy2
(Distinctive Doe)
02-12-02 18:58
No 268875
      4-methoxyphenol from p-meobenzaldehyde
(Rated as: excellent)
 Bookmark   

US 5,840,997

4-Methoxyphenol

In a 500 mL flask were placed 5.0 g (36.7 mmol) of p-anisaldehyde and 184 mL of methylene chloride (0.2M). This mixture was vigorously stirred with a magnetic stir bar. To the homogeneous solution was added 9.37 mL of 30% aqueous hydrogen peroxide (92.0 mmol., 2.5 equivalents) and 5.54 mL of formic acid (147 mmol., 4.0 equivalents). The flask was then fitted with a reflux condenser and heated to reflux for 20.5 hours with stirring.

After cooling, 119 mL of 1.5N sodium hydroxide (179 mmol., 4.86 equivalents) was added to the flask. The mixture was stirred for 15 minutes. The organic layer was separated and concentrated to a residue using a rotary evaporator. The residue was combined with the aqueous solution and 79.3 mL of methanol was added. The solution was stirred for 30 minutes. The methanol was removed using a rotary evaporator.

The neutral materials were removed from the aqueous residue by extracting with two 100 mL portions of methylene chloride. The solution was adjusted to a pH of 1 to 2 with concentrated hydrochloric acid. The 4-methoxyphenol was extracted with three 100 mL portions of methylene chloride.

The organic solution containing the neutrals as well as the one containing the product were separately dried over anhydrous magnesium sulfate and filtered into tared round-bottom flasks. The methylene chloride was removed using a rotary evaporator. A total of 0.052 g of neutrals was recovered. A total of 4.13 g of the crude 4-methoxyphenol was obtained (33.3 mmol., 90.7% yield).

The 4-methoxyphenol was purified utilizing bulb-to-bulb distillation. A mass of 3.88 g of 4-methoxyphenol as a white crystalline solid was obtained (31.3 mmol., 85.1 % yield). The purity was determined by GC (99.7%) as well as HPLC (99.3%).



Here are some other references.

The oxidation of 4-methoxybenzaldehyde using the system hydrogen peroxide-boric acid-sulfuric acid gave 4-methoxyphenol in 97% yield,[11] and using m-chloroperoxybenzoic acid in 92% yield.[12]

11. A. Roy, K.R. Reddy, P.K. Mohanta, H. Ila and H. Junjappa
Synth. Commun. 29 (1999), pp. 3781-3791. 

12. I.M. Godfrey, M.V. Sargent and J.A. Elix
J. Chem. Soc., Perkin Trans. 1 (1974), pp. 1354-1363.


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    psychokitty
(Her Majesty, Stoni's Kitty)
03-02-02 19:34
No 276050
      Re: 4-methoxyphenol from p-meobenzaldehyde  Bookmark   

Ahh, yes!  React allyl bromide or allyl chloride and sodium iodide, p-methoxyphenol, and potassium carbonate in acetone solvent to form the--whatever you'd call it--1-allyloxy-4-methoxy-benzene, which through claisen rearrangement should form the 1-allyl-2-hydroxy-5-methoxy-benzene.  Or would it be 1-allyl-2-methoxy-5-hydroxy-benzene?  Either way, methylation with dimethyl sulfate or methyl iodide in base (with or without PTC) of the phenolic group will yield, 1-allyl-2,5-dimethoxy-benzene.

BTW, foxy2, did you get my PM?
 
 
 
 
    Lilienthal
(Moderator)
03-03-02 07:58
No 276246
      Re: 4-methoxyphenol from p-meobenzaldehyde  Bookmark   

[sidenote]Somebody asked for the smell of 4-MeO-phenol a while ago. It smells like phenol, but much weaker. And behind that there is a weak smell like a camp fire place after a rain.smile[/sidenote]
 
 
 
 
    Antoncho
(Official Hive Translator)
03-03-02 08:40
No 276256
      Re: 4-methoxyphenol from p-meobenzaldehyde  Bookmark   

Spasibo, Lili, this was very helpful, indeed.


Antoncho
 
 
 
 
    Rhodium
(Chief Bee)
03-03-02 09:46
No 276279
      Re: 4-methoxyphenol from p-meobenzaldehyde  Bookmark   

Psychokitty, the details of the synthesis you suggest can be found here: ../rhodium/chemistry /25.meo.allylbenzene.html