CONFIDENTIAL TREATMENT

Note: Portions of this exhibit have been omitted pursuant to a request for
confidential treatment filed with the Commission under Rule 24b-2. The omitted
confidential material has been filed separately with the Commission. The
location of the omitted confidential information is indicated herein by an "X".



                     SECOND AMENDMENT TO PURCHASE AGREEMENT


         This SECOND AMENDMENT, dated as of December 9, 2000 (the "Second
Amendment"), to the PURCHASE AGREEMENT dated as of March 20, 2000, as amended by
the First Amendment dated as of June 30, 2000 (the "Agreement"), by and among
AMERICAN CYANAMID COMPANY, a Maine Corporation ("Cyanamid"), AMERICAN HOME
PRODUCTS CORPORATION, a Delaware corporation ("AHP" and, together with Cyanamid,
"Sellers"), and BASF Aktiengesellschaft, a corporation organized under the laws
of Germany ("Buyer"). All terms not otherwise defined herein shall have the
meanings ascribed thereto in the Agreement.


                              W I T N E S S E T H:
                               - - - - - - - - - -

         WHEREAS, the parties hereto have heretofore entered into the Agreement;

         WHEREAS, the parties hereto have entered into the First Amendment to
the Purchase Agreement effective as of June 30, 2000 (the "First Amendment");

         WHEREAS, the parties hereto desire to further amend the Agreement
as provided in this Second Amendment;

         NOW, THEREFORE, in consideration of the foregoing premises and the
representations, warranties, covenants and agreements herein contained, and for
other good and valuable consideration, the parties hereto, intending to be
legally bound, agree as follows:

1.       With respect to certain Joint Venture Interests, the Agreement is
hereby amended as follows:

(i)               by adding to Section 3.4(d) of the Agreement the words
                  "Transferable Joint Venture Interests, and the" before the
                  word "Other" in the second line of such Section; and

(ii)              by deleting from Section 3.4(d) of the Disclosure Schedule the
                  first paragraph and substituting in lieu thereof the language
                  set forth on Annex I to this Second Amendment.

         Buyer hereby agrees (i) to pay all out-of-pocket costs related to the
         formation of any new companies and all transfer taxes, fees, duties
         (excluding income and net worth taxes) and other out-of-pocket costs
         related to the changes and actions set forth in Annex I hereto, but
         only to the extent that such costs exceed the costs that would have
         been incurred had such changes and actions not occurred, and (ii) that
         any breach of any representation, warranty or covenant of Sellers
         contained in the Agreement occurring as a result of such actions or
         changes shall be deemed not to have occurred and shall not entitle
         Buyer to any right, remedy or recourse against Sellers or their
         Affiliates in respect thereto.

2.       With respect to certain pension liabilities, and for purposes of
clarification only, the Agreement is hereby amended as follows:

         (i)      by adding an "(a)" before the word "Seller" in the first
                  line of Section 7.14 (which is set forth in Section 16 of
                  the First Amendment); and

         (ii)     by inserting new paragraphs (b), (c),(d), (e) and (f) to
                  Section 7.14 as follows:

                  "(b)     For purposes of this Section 7.14 only, the
                           definitions set forth on Annex II to the Second
                           Amendment shall apply to the defined terms used in
                           this Section 7.14.

                   (c)     Pension liabilities with respect to Active Employees
                           and Vested Employees are included in the Excluded
                           Liabilities and shall remain Sellers' responsibility.
                           Sellers shall promptly reimburse Buyer or its
                           Affiliates for any payments made by Buyer or its
                           Affiliates either to Active Employees or Vested
                           Employees for pension benefits under the pension plan
                           maintained on their behalf as in effect on the
                           Closing Date, together with an amount for reasonable
                           administration costs incurred with respect to such
                           payment.

                  (d)      Pension liabilities with respect to Retirees are
                           included in the Assumed Liabilities and shall be
                           Buyer's responsibility. Buyer shall promptly
                           reimburse Sellers or their Affiliates for any
                           payments made by Sellers or their Affiliates to
                           Retirees for pension benefits under the pension plan
                           maintained on their behalf, together with an amount
                           for reasonable administration costs incurred with
                           respect to such payment.

                  (e)      Pension liabilities for those employees of XXXX who
                           are not Transferred Employees remain with XXXX, are
                           included in the Assumed Liabilities and shall be
                           Buyer's responsibility. Buyer shall promptly
                           reimburse Sellers or their Affiliates for any
                           payments made by Sellers or their Affiliates to such
                           employees for pension benefits under the pension plan
                           maintained on their behalf, together with an amount
                           for reasonable administration costs incurred with
                           respect to such payment.

                  (f)      Sellers and Buyer shall establish reasonable and
                           adequate procedures to keep each other regularly and
                           in a timely manner informed about any requests for
                           reimbursement of pension benefits as outlined in
                           paragraphs (c), (d) and (e) above."

         Within thirty (30) days after the date of this Second Amendment,
         Sellers shall provide Buyer with a complete list of the Transferred
         Employees which upon such delivery shall be deemed to be Annex III to
         this Second Amendment.

3.       The Agreement is hereby amended by inserting after the word "claim"
         in the ninth line of such Section 11.2(a) the following:

         "; provided that the failure of the Aggrieved Party to give such notice
         or any delay thereof shall not affect the Aggrieved Party's rights to
         indemnification hereunder, except to the extent such failure or delay
         impairs the Indemnifying Party's ability to defend or contest any such
         claim, action, proceeding or litigation"

4.       The Agreement is hereby amended by deleting the period at the end of
         paragraph (viii) of Section 11.1(a) and substituting in lieu thereof ";
         or" and by inserting the following language following paragraph (viii)
         of Section 11.1(a):

         "(ix) any liability, other than an Assumed Liability or an Excluded
         Liability, of a Company to the extent arising out of the conduct of a
         business, other than the Business, by such Company prior to the
         Closing, except in the event that such liability relates to an asset
         held by such Company at Closing (other than assets held by a Company at
         Closing which are not Assets and which are subsequently transferred by
         Buyer or its Affiliates to Sellers or their Affiliates) and such asset
         or liability is reflected in the Financial Statements or the Closing
         Statement."

5.       The Agreement is hereby amended by deleting from paragraph (b) of
         Exhibit A the reference to "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
         XXXXXXXXXXXXXX."

6.       Pursuant to Section  3.5(c) of the  Agreement,  the parties hereby
         agree that the Final Net Asset Value shall be $XXXXXXXXXXXXX. In
         connection therewith, the Purchase Price adjustment to be paid by
         Buyer to Sellers pursuant to Section 3.5(c)of  the  Agreement  shall
         be  reduced  by  $XXXXXXXXXX,  the amount of the pension accrual
         referred to in Section 27 of the First Amendment, resulting in a final
         Purchase Price  adjustment to be paid by Buyer to Sellers of
         $XXXXXXXXXXX. Further in  connection  therewith,  the  parties  agree
         that Buyer  shall not be entitled  to  seek  indemnification  under
         Section  7.5  or  Article  11 of the Agreement for (i) any matter
         contained in the Notice of  Disagreement,  (ii) any matter  relating
         to the Notice of  Disagreement  presented  to Sellers up to and
         including  December 8, 2000, and (iii) any matter  discussed up to
         and including December 8, 2000 in  connection  with (i) or (ii) above,
         and (iv) the effect of any  of  the  foregoing  on  the
         representations,  warranties,  agreements  and covenants contained in
         the Agreement.

7.       The parties hereby agree that the Allocation pursuant to Section
         7.5(d)(iii) of the Agreement shall be mutually agreed to by the
         parties.


8.       The Agreement is hereby amended by inserting after the word "bonus"
         in the second line of each of Sections 9.4(a)(iv) and 9.6(h) the
         following:

         "(other than the 2000 Bonus Plan attached as Annex V to the
         Second Amendment)"

9.       Exhibit A to the Agreement is amended by deleting "XXXXXXXXXXXXXX
         XXXXXXXXXXXX." from Section (b) of Exhibit A (Companies) and adding
         it to Section (a) of Exhibit A (Asset Transferor Entities). Buyer
         hereby agrees (i) to pay all out-of-pocket costs related to the
         formation of any new companies and all transfer taxes, fees, duties
         (excluding income and net worth taxes) and other out-of-pocket costs
         related to the changes and actions set forth above, but only to the
         extent that such costs exceed the costs that would have been incurred
         had such changes and actions not occurred, and (ii) that any breach
         of any representation, warranty or covenant of Sellers contained in
         the Agreement occurring as a result of such actions or changes shall
         be deemed not to have occurred and shall not entitle Buyer to any
         right, remedy or recourse against Sellers or their Affiliates in
         respect thereto.

10.      This Second Amendment shall be governed in all respects, including
         validity, interpretation and effect, by the internal laws of the
         State of New York.

11.      The parties hereto agree that the U.S. District Court for the Southern
         District of New York shall have exclusive jurisdiction over any dispute
         or controversy arising out of or in relation to this Second Amendment
         and any judgment, determination, arbitration award, finding or
         conclusion reached or rendered in any other jurisdiction shall be null
         and void between the parties hereto. Each of the parties waives any
         defense of inconvenient forum to the maintenance of any action or
         proceeding so brought and waives any bond, surety, or other security
         that might be required of any other party with respect thereto.

12.      This Second Amendment may be executed in one or more counterparts which
         together shall constitute a single agreement. If any provisions of this
         Second Amendment shall be held to be illegal, invalid or unenforceable
         under any applicable law, then such contravention or invalidity shall
         not invalidate the entire Second Amendment. Such provision shall be
         deemed to be modified to the extent necessary to render it legal, valid
         and enforceable, and if no such modification shall render it legal,
         valid and enforceable, then this Second Amendment shall be construed as
         if not containing the provision held to be invalid, and the rights and
         obligations of the parties shall be construed and enforced accordingly.

13.      This Second Amendment constitutes an amendment to the Agreement
         pursuant to Section 12.4 of the Agreement. Except as expressly amended
         by the First Amendment and this Second Amendment, each and every
         provision of the Agreement remains in full force and effect in
         accordance with the terms thereof and, by reference, the terms and
         provisions of the Agreement are incorporated herein and made a part
         hereof.


         IN WITNESS WHEREOF, this Second Amendment has been signed by each of
the parties hereto as of the date provided above.

                               AMERICAN CYANAMID COMPANY

                               By:   _______________________________________
                               Name:
                               Title:

                               AMERICAN HOME PRODUCTS CORPORATION

                               By:   _______________________________________
                               Name:
                               Title:


                               BASF AKTIENGESELLSCHAFT

                               By:   _______________________________________
                               Name:
                               Title:

                               BASF AKTIENGESELLSCHAFT

                               By:   _______________________________________
                               Name:
                               Title: