US chemicals maker Platform Specialty Products Corp said it would buy UK's Alent for about £1.35 billion ($2.09 billion) in cash to expand its portfolio and save costs.

The 503-pence-per-share offer comes at a 49 per cent premium to the British chemical maker's Friday close. Including debt, the deal is worth about $2.3 billion, the companies said.

"We believe the synergy potential is significant as is our combined ability to deliver better technology and service to our customers," Platform Specialty chief executive Daniel Leever said in a statement.

The deal includes a partial share alternative for Alent shareholders under which they can elect to receive shares in Platform Specialty in lieu of cash.

Platform Specialty said the deal would result in pretax cost synergies of about $50 million annually, phased in over three years.

The deal, which has been recommended by Alent's board, has received the backing of the London-listed company's largest shareholder Cevian.

Alent said it would not pay an interim dividend for the six months ended June 30.

Credit Suisse is the financial adviser for Platform Specialty, while Rothschild and UBS advised Alent. - Reuters