1. Longifolene, commercial, Min 95%

2. Potassiumhydrogensulfate –S. D. Fine Chem

3. Bromoacetic acid, Aldrich Chemical Co.

4. Toluene, commercial, 99%

 

To a clean 500 mL Lt 3 necked flask carrying thermometer pocket and a mechanical stirrer, was charged Longifolene (202 g, 1 mol) followed by Potassium hydrogensulfate (4 g, 2% by weight OR bromoacetic acid). The reaction mixture was heated on mantle to about 220oC (gentle reflux) and maintained at this temperature for 24 h (at this point of time, 13C NMR of the reaction mixture clearly shows the absence of 2 peaks for the olefin carbon at δ 167.36 and 99.34. You will see new peaks at δ 151.47 and 110.28 for Alloisolongifolene).The reaction mixture was cooled to about 50 oC and diluted with toluene (500 mL) and filtered. The combined organic layer thus obtained was washed with 10% sodiumcarbonate solution (250 mL) and concentrated to get about 195 g residue. This residue was distilled under vacuum (82-85 oC /1mm) to get 166 g of pale yellow Alloisolongifolene (Yield: 82%).

1. Commercially available Longifolene is sometimes 80-95% pure. This needs to be distilled to a constant boiling to make it above 95% purity before doing this reaction.

2. Reaction does not require any special reaction condition.

3. During the reaction, any liquid which distils below 200 oC to be removed.

4. It is essential to do gentle reflux throughout 24 h.

 

Alloisolongifolene: 13C NMR (22.5 MHz, CDCl3): δ 151.47, 110.28, 52.23, 49.83, 48.18, 46.99, 44.44, 39.08, 36.72, 32.93, 22.27, 21.10, 20.73, 20.11, 15.64.

Longifolene: 13C NMR (22.5 MHz, CDCl3): δ 167.36, 99.34,62.14,47.96,45.10,43.93,43.41,36.52,33.53,30.53,30.14,29.75,25.59,21.17

 

Sukh Dev. Prog. Chem. Org. Nat. Prod. 1981, 40, 49

1.  Ramesha A. Ramakrishna, Shridhar Bhat, Kandikere R. Prabhu, Org. Prep. Proc. Intl., 1999, 31(2), 227-230

1. . Nayak, U. R. Tetrahedron, 1981, 14, 82-86

2. Sukh Dev. Prog. Chem. Org. Nat. Prod. 1981, 40, 49

3. Sukh Dev. Proc. Indian National Sci. Acad, 1983, 49A, 359.