Preparation method of 2-isopropoxystyrene_Industrial additives

Background and overview^[1]

2-Isopropoxystyrene is an organic intermediate. O-(2-propoxy)salicylicaldehyde can be prepared from salicylaldehyde as raw material, and then 2-isopropoxystyrene can be prepared through Wittig reaction. styrene.

Preparation^[1]

Step 1,

Dissolve salicylaldehyde (10.3 g, 88.0 mmol), tetrabutylammonium bromide (25.1 g, 78.0 mmol) and 2-propyl iodide (20 mL, 0.20 mol) in dichloromethane (300 mL) middle. NaOH (3.5 g, 88 mmol) dissolved in water (150 mL) was slowly added to the stirring solution. After the reaction was stirred for 3 days, the organic phase was separated and the aqueous phase was washed with dichloromethane (3 x 50 mL). The combined organic phases were dried in vacuo, redissolved in ethyl acetate and filtered. The filtrate was dried over Na2SO4 and evaporated to dryness to obtain a yellow oil, which was removed under reduced pressure to obtain the intermediate O-(2-propoxy) salicylaldehyde. The spectral data were the same as those reported in the literature. Colorless liquid, yield 6.68g (48%).

Step 2,

Methyltriphenylphosphine bromide (14.1 g, 39.6 mmol) was dried in a Schlenk tube at 55°C. Anhydrous THF (55 mL) was added, followed by n-butyllithium (2N in pentane, 20.4 mL, 39.6 mmol) at 0 °C. The mixture was stirred at 0°C for 30 minutes and at room temperature for 30 minutes. O-(2-propoxy)salicylicaldehyde (6.68g, 39.6mmol) was slowly added at room temperature, and stirring was continued for 12h. Water (5 mL) was added to the yellow suspension, which was then dried under vacuum. The product was extracted with diethyl ether (3 x 25 mL) and the combined organic phases were dried over Na2SO4. Removal of all volatiles gave a clear, colorless liquid in 3.9 g (61%) yield.

References

[1] Vygodskii Y S, Shaplov A S, Lozinskaya E I, et al. Ring-Opening Metathesis Polymerization (ROMP) in Ionic Liquids: Scope and Limitations[J]. Macromolecules, 2006, 39(23):7821-7830.