Dow Chemical Co. plans to cut 4,500 jobs, or 8% of its work force, doubling its earlier job reduction estimate as it looks to bolster savings from its purchase of Union Carbide.Dow Chemical said today it plans to cuts annual costs by $1.1 billion by early 2003, more than twice its $500 million projection when the takeover of Union Carbide was announced in 1999.The Midland-based company had previously said it was cutting 4% of its work force due to cost savings found through the acquisition, incl...