Reaction #2175420

Reaction equation

Iodomethane

4-butyl-4′-hydroxyazobenzene

potassium carbonate

→

desired product

4-Butyl-4′-methoxyazobenzene

Solvents

acetone

acetone

Conditions

Workup

1. 1
   Otherdegassed with argon
2. 2
   workup.ADDITIONadded drop-wise to the stirred mixture
3. 3
   Other12 h
4. 4
   FiltrationThe hot reaction mixture was then filtered
5. 5
   Otherto remove the precipitated potassium iodide
6. 6
   OtherThe filtrate was collected
7. 7
   Otherthe solvent removed in vacuo
8. 8
   workup.DISSOLUTIONThe solid residue was re-dissolved in chloroform
9. 9
   Otherinsoluble salts were removed by filtration
10. 10
    WashThe filtrate was washed with water
11. 11
    Otherthe organic layer was separated
12. 12
    Dryingdried over magnesium sulfate
13. 13
    OtherRemoving the solvent in vacuo
14. 14
    Otherafforded a solid

Procedure

All chemicals were obtained from Sigma-Aldrich Chemical Co. unless otherwise noted. One eq. of 4-butyl-4′-hydroxyazobenzene (obtained from Beam Corp.) and 1.1 eq. potassium carbonate were dissolved in acetone and degassed with argon. Iodomethane (2.5 eq) in acetone was degassed and added drop-wise to the stirred mixture. The mixture was heated to 45° C. and stirred overnight. The progress of the reaction was monitored by thin-layer chromatography (TLC); 12 h was usually sufficient for complete methylation. The hot reaction mixture was then filtered to remove the precipitated potassium iodide. The filtrate was collected and the solvent removed in vacuo. The solid residue was re-dissolved in chloroform and then insoluble salts were removed by filtration. The filtrate was washed with water, and the organic layer was separated and dried over magnesium sulfate. Removing the solvent in vacuo afforded a solid that contained the desired product (“BMAB”) containing a small amount of un-reacted starting material 4-butyl-4′-hydroxyazobenzene. Recrystallization from methanol at −68° C. afforded pure crystals of BMAB that were collected by filtration. (K 35 N 45 I) 1H NMR 200 MHz δ ppm=0.94 (t, 3H), 1.18 (q, 2H), 1.66 (q, 2H), 2.66 (t, 2H), 3.86 (s, 2H), 7.0 (d, 2H), 7.26 (d, 2H), 7.82 (d, 2H), 7.88 (d, 2H).

Source