NEW YORK, April 29 -- Castle Harlan, Inc., the New York merchant bank, said today that an affiliated investment partnership had completed the previously announced sale of its stake in INDSPEC Chemical Corporation to Occidental Petroleum Corp. as part of a transaction valued at $300 million.

The investment partnership, Castle Harlan Partners II, L.P., acquired INDSPEC in December 1993, along with INDSPEC management, employees and the Employee Stock Ownership Plan. For the partnership, the sale represented a five-fold return on its 28-month investment.

INDSPEC, based in Pittsburgh, is a specialty chemical company that is the world's leading producer of resorcinol, a versatile compound used in tires, adhesives, sunscreens, dyestuffs, fire retardants and pharmaceuticals.

Castle Harlan, established in 1987, is headed by John Castle, former president and CEO of Donaldson, Lufkin & Jenrette, and Leonard Harlan, founder and former chairman of The Harlan Company, a real estate investment and advisory company he recently sold to Ernst & Young, the accounting firm.