EXHIBIT 3(i)(a) CERTIFICATE OF AMENDMENT OF AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF CK WITCO CORPORATION CK Witco Corporation, a Delaware corporation (the "Corporation"), does hereby certify: FIRST: That Article I of the Amended and Restated Certificate of Incorporation of the Corporation is hereby amended to read in its entirety as follows: ARTICLE I The name of the Corporation is Crompton Corporation. SECOND: That said amendment was duly adopted in accordance with the provisions of Section 242 of the General Corporation Law of the State of Delware. In witness whereof, CK Witco Corporation has caused this Certificate to be executed by its duly authorized officer, this 27th day of April, 2000. By: /s/John T. Ferguson II Name: John T. Ferguson II Title: Senior Vice President