2,2,5,7,8-PENTAMETHYLCHROMAN synthesis
- Product Name:2,2,5,7,8-PENTAMETHYLCHROMAN
- CAS Number:55646-01-0
- Molecular formula:C14H20O
- Molecular Weight:204.31
Yield:55646-01-0 49%
Reaction Conditions:
with acetic acid;zinc(II) chloride at 20; for 22 h;Reflux;
Steps:
2.E 2,2,5,7,8-Pentamethylchroman
2,3,5-Trimethylphenol (50.03 g, 0.367 moles), isoprene (25.09 g, 0.368 moles) and fused zinc chloride (5.94 g, 0.044 moles) was stirred with anhydrous acetic acid (47 ml) for 14 hours at room temperature. The cloudy red coloured mixture was then gradually heated and it became clear. Upon refluxing the reaction mixture turned black, and after 8 hours of reflux it was cooled to room temperature. The reaction mixture was poured into 250 ml water and the black oil separated. The water was extracted with pentane (3×200 ml) and the combined organic phases washed with Claisen's alkali (2×150 ml), water (3×250 ml) and brine (2×200 ml), dried over CaCl2 and evaporated to a brown oil under reduced pressure. The crude product was distilled at 0.48 mBar affording the product as a pale yellow liquid (36.90 g, 49% yield); b.p. 82-96° C. (0.48 mBar); >95% pure (GC).1H NMR (CDCl3, 400 MHz): δ=1.30 (6H, s, 2×CH3), 1.78 (2H, t, J=7 Hz, CH2), 2.07 (3H, s, CH3), 2.15 (3H, s, CH3), 2.19 (3H, s, CH3), 2.59 (2H, t, J=7 Hz, CH2), 6.54 (1H, s, aromatic H).13C NMR (CDCl3, 400 MHz): δ=11.42 (CH3), 18.91 (CH3), 19.84 (CH3), 20.49 (CH2), 26.97 (2×CH3), 32.79 (CH3), 73.10 (C(CH3)2), 116.67 (Ar-C), 122.03 (Ar-C), 122.29 (Ar-C), 133.44 (Ar-C, 134.70 (Ar-C), 151.72 (Ar-C). (0239) MS (GC/MS): m/z=204(100), 189(14), 149 (91).
References:
US9109048,2015,B2 Location in patent:Page/Page column 34; 35
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