(Correct Platform's unit name in paragraph 6 to MacDermid from McDermid)
* 503p/shr offer at 49 pct premium
* Including debt, deal is valued at $2.3 bln
* Alent shares up 45 pct, top FTSE midcap gainer
July 13 (Reuters) - U.S. chemicals maker Platform Specialty Products Corp said it would buy UK's Alent Plc for about 1.35 billion pounds ($2.09 billion) in cash to expand its portfolio and save costs, sending shares of Alent to their highest on record.
The British chemicals maker's shares rose 45 percent to an all-time high on the London Stock Exchange. The stock was the top gainer on the FTSE-250 Midcap Index.
The 503-pence-per-share offer from Platform Specialty is at a 49 percent premium to Alent's closing price on Friday. Including debt, the deal is worth about $2.3 billion, the companies said.
The deal, Platform's eighth in the last three years, is expected to help the combined entity save about $50 million in costs annually before tax.
Platform most recently bought OM Group Inc's industrial chemicals unit in June.
Platform said it would integrate Alent into its performance applications unit, MacDermid, which competes with the British firm to make chemicals used in the electronics and automotive industries.
The deal, which has the backing of Alent's board and its largest shareholder Cevian Capital, includes an option for Alent shareholders to receive 0.31523 Platform shares for each Alent share instead of cash.
However, the plan is limited to about 58.4 million shares, or 21.9 percent of Alent's total outstanding shares of around 266.4 million shares as of Monday.
Alent was previously Cookson Group's performance materials unit before it was spun off in 2012.
Alent said it would not pay an interim dividend for the six months ended June 30.
Credit Suisse was the financial adviser for Platform, while Rothschild and UBS advised Alent. ($1 = 0.6446 pounds) (Reporting By Mamidipudi Soumithri in Bengaluru; Editing by Gopakumar Warrier and Biju Dwarakanath)