Hubert W. Brucker has been named director of marketing and sales for E.C. Ernst Inc. Brucker was previously manager of the Washington chapter of the National Electrical Contractors Association.

Sydney V. Stern has been named vice president of coordination and planning in the Crown Central Petroleum Corp. petroleum products division. Stern has been with Conoco Inc. for the past 20 years. He was most recently manager of product development, logistics and downstream planning.

Jimmie R. Bowden, former vice president of government relations for Conoco Chemicals Co., has been elected executive vice president of the U.S. Synthetic Fuels Corp. Edward S. Miller, former senior vice president of AMAX Inc., was elected the corporation's vice president of finance.

Vincent N. Cook has been elected a vice president of IBM. He will continue as president of the company's federal systems division, located in Bethesda.

In a related development, Albert E. Babbitt has been named vice president of a new command, control and communications group in IBM's federal systems division. Babbitt was formerly the division's vice president of space systems.

Hrant K. Baboyian has been appointed vice president of administration and planning for UOP Inc. He was formerly the company's vice president of government relations here. In his new position, Baboyian will be located in the UOP headquarters in Des Plaines, Ill.