Uses
2,5-Di(tert-amyl)hydroquinone can be used as a pharmaceutical synthesis intermediate and can be used in laboratory research and development as well as in chemical and pharmaceutical synthesis processes.
Synthesis
2,5-Di-tert-pentylhydroquinone was prepared as follows: 110.1 g (1.000 mol) of hydroquinone (HQ) was placed in an autoclave along with 132.0 g of toluene. After purging with N2, 30 g (0.0343 mol) of methanesulfonic acid was added and the mixture was heated to 60 C. Starting at 55 C, 158.8 g (2.260 mol) isopentene was added over 3.5 h. The secondary reaction was carried out at 65-70 C for 3.5 h. The reaction mixture was then diluted with 397.6 g toluene. Then 25.7 g (8%, 0.0245 mol) of NaHCO3 solution was added over 7 min at 70 C. This was used to neutralize about 70% of the free acid. In order to effectively neutralize the acid residues remaining in the cured product and to eliminate the intermediate formation of quinones, 74.1 g of an aqueous solution consisting of 4% Na2HPO4 as well as 1% Na2SO3 was added over 23 min while the reaction mixture was heated to 90C to ensure complete dissolution of the product. After stirring for 25 minutes, the heavy aqueous phase was discharged at a. Thereafter, 196.3 g of the buffer solution (II) used above was added and another wash was performed under the same conditions. The pH of the drained aqueous phase was 7. To remove salt impurities, 171.3 g of deionized water was added and stirred for 60 min then the aqueous phase was drained. The organic solution was gradually cooled to 0 C to allow precipitation. After filtration at this temperature and washing with 200 g of cold toluene, the product 2,5-di-tert-pentylhydroquinone was dried at the highest temperature in 92% yield (relative to hydroquinone (HQ).
Purification Methods
Crystallise the hydroquinone under N2 from boiling AcOH (7mL/g) plus boiling water (2.5mL/g). [Stolow & Bonaventura J Am Chem Soc 85 3636 1963]. Store it in sealed ampoules under N2 away from light. [Beilstein 6 H 952, 6 III 4748.]
