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                                                                   EXHIBIT 5.01


                               December 16, 1996


Aristech Chemical Corporation
600 Grant Street
Pittsburgh, PA 15219


Ladies and Gentlemen:

        I am the General Counsel and Corporate Secretary of Aristech Chemical 
Corporation, a Delaware corporation (the "Company"). In that capacity, I have 
acted as counsel to the Company in connection with the filing by the Company of 
a Registration Statement on Form S-4 under the Securities Act of 1933, as 
amended (the "Securities Act") with the Securities and Exchange Commission. 
The Registration Statement relates to the proposed issuance of up to 
$150,000,000 aggregate principal amount of the Company's 6-7/8% notes due 2006 
(the "New Notes") registered under the Securities Act in exchange for a like 
principal amount of the Company's outstanding 6-7/8% notes due 2006 (the "Old 
Notes"). The New Notes are issuable, and the Old Notes were issued, under an 
Indentures dated as of November 1, 1996 (the "Indenture") between the Company 
and The Chase Manhattan Bank, as Trustee (the "Trustee").

        I have examined the Registration Statement, the Indenture and the 
Company's Restated Certificate of Incorporation and By-laws, each as amended 
to date. I have also examined such other public and corporate documents, 
certificates, instruments and corporate records, and such questions of law, 
I have deemed necessary for purposes of this opinion. 

        In making such examination and rendering the opinion set forth below, 
I have assumed the genuineness of all signatures, the authenticity of all 
documents submitted to me as originals and the conformity to original documents 
of documents submitted to me as certified, telecopied, photostatic or 
reproduced copies and the authenticity of the originals of such documents, and 
the execution and delivery of all such documents and instruments.

        To the extent relevant to the opinion set forth below, I have assumed 
that the Trustee is duly organized, validly existing and in good standing under 
the laws of its jurisdiction of organization; that the Trustee is duly 
qualified to engage in the activities contemplated by the Indenture and is 
qualified and eligible under the terms of the Indenture to act as trustee

 

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thereunder; that the Indenture was duly authorized, executed and delivered by 
the Trustee; that the Indenture is a valid and binding obligation of the 
Trustee; and that the Trustee has the requisite organizational and legal power 
and authority to perform its obligations under the Indenture.

        Based upon the foregoing, and subject to the effectiveness of the 
Registration Statement under the Securities Act and the qualification of the 
Indenture under the Trust Indenture Act of 1939, as amended, I am of the 
opinion that, when the New Notes are duly executed, attested, issued and 
delivered by duly authorized officers of the Company and duly authenticated by 
the Trustee, all in accordance with the terms of the Indenture, against 
surrender and cancellation of a like principal amount of Old Notes, the New 
Notes will constitute legally issued and binding obligations of the Company, 
enforceable against the Company in accordance with their terms, except to the 
extent that enforcement thereof may be limited by bankruptcy, insolvency 
(including, without limitation all laws relating to fraudulent transfers), 
reorganization, moratorium or other similar laws relating to or affecting 
enforcement of creditors' rights generally, or by general principals of equity 
(regardless of whether such enforcement is considered in a proceeding in equity 
or at law).

        I consent to the use of this opinion as Exhibit 5.01 to the 
Registration Statement and to the reference to the undersigned in the 
prospectus that forms part of the Registration Statement.


                                        Yours truly,

                                        /s/ MARK K. MCNALLY

                                        Mark K. McNally
                                        General Counsel and
                                          Corporate Secretary