August 10, 1998


                                                                     EXHIBIT 2.2


Clark Refining & Marketing, Inc.
8182 Maryland Avenue
St. Louis, MO 63105


Re:  Letter Amendment No. 1 to Agreement for Purchase and Sale of Lima Oil
     Refinery dated July 1, 1998 (the "Agreement")


Dear Sir:

Whereas the parties to the Agreement wish to amend the same. It is agreed as
follows:

1.   Addition of Section 1.M.

     The following Section 1.M. is hereby added to the Agreement after Section
     1.L.:

     M.   An ownership interest in the natural gas pipelines used to supply
          natural gas to the Refinery and others in the Lima industrial complex,
          in the form of a Capacity Lease Agreement to be agreed between the
          parties.

2.   Addition of Section 2.0.

     The following Section 2.0. is hereby added to the Agreement after Section
     2.N.:

     O.   An ownership interest in the electrical equipment used to supply
          electricity to the Refinery and others in the Lima industrial complex,
          in a form to be agreed between the parties.

3.   Amendment of Sections 3.B. and 3.C.

     Section 3.B. and 3.C. of the Agreement are hereby amended to read, in their
     entirety, as follows:

     B.   Purchase Price. In consideration for the Purchased Assets, Buyer shall
          pay to Seller or its affiliates on the Closing Date in immediately
          available funds, by wire transfer to Seller's account number 2092551
          at National City Bank, Cleveland, Ohio (ABA or Transit Routing Number
          041000124) an amount equal to: (i) One Hundred Sixty Six Million Two
          Hundred and Fifty Thousand Dollars ($166,250,000.00), and (ii) an
          amount equal to the Estimated Inventory Value, as defined in Section 4
          below, subject to adjustment for the Final Inventories Value as
          specified in Schedule E, (iii) less an amount equal to the

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          Deposit; and (iv) assume and agree to pay and perform the liabilities
          and obligations of Seller specified in Section 5 below relating to the
          Purchased Assets (the "Purchase Price"). Additionally, Buyer shall pay
          by wire transfer to the Escrow Account of #2249491 Security Inc. at
          National City Bank, Cleveland, Ohio (ABA or Transit Routing Number
          041000124), reference Lima Oil Refinery, an amount equal to: Eight
          Million, Seven Hundred Fifty Thousand Dollars ($8,750,000.00) in order
          to facilitate a like-kind exchange under Section 1031 of the Code.

     C.   Purchase Price Allocation. Buyer and Seller shall agree on an
          allocation of the Purchase Price (including any adjustments thereto)
          among the parties pursuant to the provisions of Section 1060 of the
          Internal Revenue Code of 1986, as amended (the "Code") and the
          regulations promulgated thereunder. Seller and Buyer agree that the
          fair market value of the land, land improvements and other real
          property included in the Purchased Assets is $8.75 million, and that
          accordingly, of the total Purchase Price, $8.75 million shall be
          allocated to said property. Buyer and Seller shall not take any
          position on their respective Tax Returns that is inconsistent with the
          allocation of the Purchase Price. Buyer and Seller shall duly prepare
          and timely file such reports and information returns as may be
          required under Section 1060 of the Code and the regulations
          promulgated thereunder, and report the allocation of the Purchase
          Price among the Assets as so agreed. Any adjustments to Purchase Price
          shall be allocated in the same manner.

4.   Sections 16.G., 16.H. and 16.I. are hereby amended to read, in their
     entirety, as follows:

     16.  Indemnification

     G.   Time Limitation. Any claim under Section 16.A.(ii)(y), or
          16.B.(ii)(y), for Indemnity arising under or out of this Agreement or
          the transactions contemplated hereunder (other than a breach of
          Section 8, which will be subject to the 17 year time limitation set
          forth below) for breach of warranty shall be brought within one year
          after the Closing Date. Any claim under Section 16.B.(ii)(x) for
          Indemnity arising under or out of this Agreement or the transactions
          contemplated hereunder for breach of Section 11.B. shall be brought
          within one year after the Closing Date, unless prior to such breach
          Seller had knowledge of the action to be taken resulting in the
          breach, in which event this limitation shall not apply. Any claim
          under Section 8. or Section 16.B.(v), (vi) or (vii) for Indemnity (in
          each case except to the extent relating to any Waste Unit) shall be
          brought within seventeen (17) years after the Closing Date. a claim
          shall be deemed to have been brought only upon delivery of a written
          notice to the other party (which notice may consist of a notice of
          breach pursuant to paragraph E.(v) of this Section 16.) at the notice
          address set forth in Section 20., stating with reasonable specificity
          the basis for the claim. Any claim required to be made within such one
          or seventeen year

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          period not so timely made will be forever barred. This provision shall
          not be deemed to limit any claims or rights to Indemnification for
          third party claims or pursuant to Sections 16.A.(i), 16.A.(iii),
          16.B.(i) or 16.B.(ii)(x), (other than as provided above with respect
          to Section 11.B), 16.B.(ii) or 16.B.(iv).

     H.   Monetary Limitation. The Buyer shall have no claim under Section
          16.B.(ii)(y) or (except in the circumstances described in the
          following sentence) under Section 16.B.(ii)(x) with respect to a
          breach of Section 11.B. against Seller for any Losses unless and until
          the aggregate of all such Losses incurred or sustained by the Buyer
          exceeds Three Million Five Hundred Thousand Dollars ($3,500,000.00)
          and then only for the excess over Three Million Five Hundred Thousand
          Dollars ($3,500,000.00) (the "Threshold"). Claims under Section
          16.B.(ii)(x) with respect to a breach of Section 11.B. shall not be
          subject to or be counted for purposes of the preceding sentence if
          Seller had knowledge of the action to be taken resulting in the
          breach, in which event the limitation in the preceding sentence shall
          not apply. After the Threshold has been reached, Seller shall have no
          obligation to Indemnify the Buyer Indemnified Parties under this
          Section 16. with respect to matters subject to the limitations
          contained in the first sentence of this Section 16.H. for any Losses
          amounting to less than Fifty Thousand Dollars ($50,000.00) in the
          aggregate arising out of the same occurrence or matter. The monetary
          limitations in this Section 16.H. will not apply to any Losses arising
          pursuant to the provisions of Section 8. or out of a breach of
          representation or warranty contained in Section 8. The provisions of
          this Section 16.H. and of 16.I. shall not apply to any breach of the
          last sentence of Section 7.G.

     I.   Limitation of Liability. Seller's aggregate liability for
          Indemnification pursuant to Section 16.B.(ii)(y), or under Section
          16.B(ii)(x) with respect to a breach of Section 11.B. in circumstances
          where Seller did not have knowledge, prior to the breach, of action
          taken that resulted in the breach of Section 11.B. shall in no event
          exceed an amount equal to Twenty Five Million Dollars
          ($25,000,000.00). This provision shall not limit Seller's liability
          for Excluded Liabilities or for Losses pursuant to the provisions of
          Section 8 or out of a breach of representation or warranty contained
          in Section 8.

5.   Amendment of Section 25.B.

     Section 25.B. of the Agreement is hereby amended to read, in its entirety,
     as follows:

     B.   All of the terms, covenants, representations, warranties and
          conditions of this Agreement shall be binding upon, and inure to the
          benefit of, and be enforceable by, the parties hereto and their
          respective successors, heirs, and other legal representatives. This
          Agreement and the rights and obligation hereunder shall not be
          assigned by any party hereto except that either party may assign its
          rights and duties to any affiliate provided that the assigning party
          shall remain liable for any such affiliate's duties, obligations
          and/or

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          liabilities hereunder, provided that with the prior written consent of
          Seller (which consent will not be unreasonably withheld or delayed)
          after the Closing Buyer may assign its rights and obligations under
          this Agreement and (as to future obligations only) be released
          therefrom to any purchaser of all or substantially all of the assets
          of the Refinery. For purposes of the immediately preceding proviso,
          Seller's withholding of consent will be deemed unreasonable unless the
          financial strength or operating capability of the proposed purchaser
          is reasonably expected to increase Seller's liability or costs
          hereunder, or materially and adversely affect Seller's ability to
          realize on the Indemnification provided to Seller under Sections 8.
          and 16. Competitive considerations will not enter into Seller's
          assessment.

          Notwithstanding anything to the contrary herein, Seller shall have the
          right to assign this Agreement, in whole or in part, to an
          intermediary party for purposes of completing a like-kind exchange of
          properties pursuant to Section 1031 of the Code. The parties
          understand that the Seller desires to receive "replacement property"
          (as that term is defined in Treasury Reg. (S)1.103(k)-
          1(a))("Replacement Property") in full or partial exchange for the
          Purchased Assets in a like-kind exchange under Section 1031 of the
          Code if suitable Replacement Property can be identified and obtained.
          Buyer agrees to take all reasonable steps to facilitate such like-kind
          exchange, including executing any documents and instruments necessary
          to consummate such like-kind exchange, as may be reasonably requested
          by the Seller, provided that Buyer shall not be required hereby to
          incur any additional liability or unreimbursed expense. The completion
          of such like-kind exchange shall not alter the Buyer's rights
          hereunder and Buyer shall have no obligation to find, select or obtain
          any Replacement Property.

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6.   Except as amended herein, and as provided in the letter from Clark dated 20
     July 98 titled Resolution Of Due Diligence Issues, the Agreement remains in
     full force and effect.

In witness whereof, the parties have duly executed this instrument the day and
year first above written.


BP EXPLORATION & OIL INC.              THE STANDARD OIL COMPANY
                            
                            
By: /s/ D. J. Atton                    By: /s/ D. J. Atton
    ---------------------                  ----------------------------
        D.J. Atton                             D.J. Atton
Title:  Vice President                 Title:  Attorney-In-Fact
                            
                            

BP OIL PIPELINE COMPANY                CLARK REFINING & MARKETING, INC.
                            
                            
By: /s/ D. J. Atton                    By: /s/ Maura J. Clark
    ---------------------                  ----------------------------
        D.J. Atton                             Maura J. Clark
Title:  Attorney-In-Fact               Title:



BY CHEMICALS, INC.


By: /s/ D. J. Atton
    ---------------------
        D.J. Atton
Title:  Attorney-In-Fact