foxy2
(Distinctive Doe)
10-01-01 20:43
No 219090
      2,5-DMB from Toluhydroquinone
(Rated as: excellent)
 Bookmark   

Here we go!
They do not explicitly produce 2,5-DMB however i am almost positive this will work. 

Selective Oxidation at Carbon Adjacent to Aromatic Systems with IBX
J. Am. Chem. Soc., 123 (13), 3183 -3185, 2001.

As shown in Table 1, the IBX-induced oxidation of benzylic positions is quite general and proceeds efficiently in fluorobenzene/DMSO (2:1) or DMSO at 80-90 C. The reaction is not affected by the presence of water (entry 3), o-substituents (entries 4, 9, 11, 14, 17), or the presence of halogens (entries 5, 6). Over-oxidation to the corresponding carboxylic acid was not observed even in the presence of electron-rich substrates (entry 7). n-Butylbenzene enters the reaction smoothly, furnishing n-butyrophenone, and so do methylnaphthalenes (entry 7) and tetrahydronaphthalenes (entries 9, 22), furnishing the corresponding ketones. The expected retardation of the reaction by electron-withdrawing substituents (vide infra) (entries 23, 24) allows selective oxidation of xylenes and tetrahydronaphthalenes to mono-carbonyl systems (entries 11, 12, 9, 22). Noteworthy is the observation that whereas the presence of olefins, N-heterocycles, amides, and aldehydes would ordinarily interfere with such benzylic oxidations by a variety of reagents the present IBX-based method performs admirably in such circumstances. Thus, oxidation of the unsaturated substituted toluenes in entries 13 and 14 with IBX proceeds smoothly as compared to the use of DDQ, PDC, or CAN, all of which led to low conversion or decomposition.5 It was also interesting to observe the stepwise oxidation of the substrate of entry 15 leading, at 65 C (2.5 equiv IBX), to the ,-unsaturated aldehyde1d and, under more forcing conditions (85 C, 4.0 equiv IBX), to the bis-aldehyde shown in entry 16. In an intermolecular competition experiment, cyclodecanol and p-tert-butyltoluene were allowed to react with IBX (2.5 equiv, 65 C, fluorobenzene/DMSO 2:1) leading only to 2-cyclodecen-1-one and no aromatic aldehyde. While slightly longer times or higher temperatures were necessary for the oxidation of N-containing aromatic systems, it is noteworthy that no N-oxidation was observed in such cases (entries 17, 18). The amide functionality did not hamper the oxidation reaction as demonstrated in entries 19 and 20, but remarkably, the reaction could be turned toward the oxazolidinone pathway by modulating the reactivity of the reagent simply by switching from fluorobenzene/DMSO to THF/DMSO as solvent (entry 21).

Reactant                   Product           Yeild   Conditions(Hr, temp, IBX eq)

Toluene                    Benzaldehyde        85%   12hr, 85C, 3 eq

o-phenyltoluene         o-phenylbenzaldehyde   78%   20hr, 90C, 3 eq

3,4-dimethoxytoluene 3,4-dimethoxybenzaldehyde  80%  5hr, 75C, 3 eq

o-xylene              o-methylbenzaldehyde       82%  ,16hr, 85C, 3 eq


Synthesis of IBX  Post 219075 (foxy2: "2-Iodoxybenzoic Acid (IBX) Synthesis", Chemistry Discourse)

Synthesis of toluhydroquinone
../rhodium/chemistry /quinones.html



Do Your Part To Win The War
 
 
 
 
    wolfx
(Hive Bee)
03-28-02 01:34
No 288759
      2,5-DMB from Toluhydroquinone  Bookmark   

Very interesting.

Is it necessary to methylate anything, before or after ?
 
 
 
 
    PolytheneSam
(Master Searcher)
03-28-02 02:25
No 288768
      benzaldehydes  Bookmark   

How about this?  Patent US3531519

http://www.geocities.com/dritte123/PSPF.html
The hardest thing to explain is the obvious
 
 
 
 
    PolytheneSam
(Master Searcher)
03-28-02 03:16
No 288784
      US 613460  Bookmark   

Patent US613460
The methyl ether of para cresol gives an aldehyde, but not the ortho form under the same conditions.

http://www.geocities.com/dritte123/PSPF.html
The hardest thing to explain is the obvious