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                                                                   EXHIBIT 10.15


                  [Letterhead of PetroChemNet Holdings, Inc.]



November 11, 1999

E.I. du Pont de Nemours and Company
1007 Market Street
Wilmington, DE 19898

Gentlemen:

         This letter will evidence our mutual understanding and agreement with
respect to the strategic alliance (the "Strategic Alliance") between
PetroChemNet Holdings, Inc., a Delaware corporation ("PCN, CheMatch, or the
Company") and E. I. du Pont de Nemours and Company, a Delaware corporation
("DuPont").

1.       DuPont Purchase of PCN Preferred Stock.

         (a)  DuPont will purchase for cash $7 million of PCN Series C Preferred
              Stock at the same price and subject to the same terms and
              conditions as the other purchasers of the Series C Preferred Stock
              at the closing of the Series C Preferred Stock financing ("the
              Series C Preferred Stock Financing"). The target closing date for
              the Series C Preferred Stock Financing is November 18, 1999.

2        DuPont Purchase of PCN Common Stock

         (a)  DuPont shall, simultaneous with the closing of the Series C
              Preferred Stock Financing, purchase a number of shares of PCN
              Common Stock equal to $5,000,000, divided by the price per share
              paid for the Series C Preferred Stock. The consideration for the
              purchase of the Common Stock shall consist of $.01 per share cash,
              and other good and valuable consideration including goods and
              services as further described herein.

         (b)  DuPont will work with PCN to add those potential customers agreed
              by the parties to the customers using the CheMatch platform of PCN
              for trading products. For each such customer up to a maximum of 20
              customers, that completes at least five (5) traces prior to
              December 31, 2000, with third parties other than DuPont on the
              CheMatch platform at the standard rates charged for the use of the
              CheMatch platform, DuPont shall earn a commission of $100,000. In
              lieu of a cash payment, DuPont will use such commission to
              purchase a number of shares of Common Stock of PCN equal to such
              $100,000, divided by the Fair Market Value per share of Common
              Stock. For the purposes of this paragraph 2(b), "Fair Market
              Value" shall mean (i) the price per share paid for the Series C
              Preferred Stock until the date 120 days from 1 December 1999, or
              (ii) thereafter, the per share price based on the most recent
              transaction value or appraisal, if PCN has not completed its
              initial public offering, or if PCN has completed its initial
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         public offering, the closing price of PCN's Common Stock on the date of
         the fifth trade that meets the condition set forth above.

    (c)  DuPont shall have the right to purchase, prior to the closing of the
         initial public offering of Common Stock of PCN registered under the
         Securities Act of 1933, as amended, additional shares of PCN Common
         Stock, so that after such purchase DuPont would own 10% of the "fully
         diluted" Common Stock of PCN. In determining "fully diluted" Common
         Stock, all outstanding consultant, employee and director stock options
         shall be assumed to be exercised, all warrants shall be assumed to be
         exercised at a net amount using the Fair Market Value of the Common
         Stock, and all Preferred Stock shall be assumed to be converted at the
         conversion price in effect at that time. For the purposes of this
         paragraph 2(c), "Fair Market Value" shall mean the per shares price to
         public in the initial public offering of Common Stock in the event that
         DuPont shall exercise its right to purchase such additional shares in
         connection with the initial public offering of Common Stock of PCN, or
         the per share price based on the most recent transaction value or
         appraisal if such purchase is not in connection with the initial public
         offering. For the purposes of this paragraph 2(c), DuPont shall be
         deemed to have exercised its right hereunder in connection with the
         initial public offering of Common Stock of PCN, if prior to any written
         notice to PCN by DuPont that it is exercising its right to purchase
         additional shares of Common Stock under this paragraph 2(c), PCN
         notifies DuPont in writing that it is contemplating filing a
         registration statement with the Securities and Exchange Commission for
         an initial public offering of its Common Stock within the following 60
         days. DuPont shall have 15 days after receipt of such notice to
         exercise its right to purchase under this paragraph 2(c) by sending
         written notice to PCN of such exercise. If DuPont fails to send such
         notice to PCN within the time set forth above, DuPont shall be deemed
         to have waived its right to purchase any additional shares of Common
         Stock of PCN in the event that the contemplated initial public offering
         of Common Stock of PCN is completed. If DuPont exercises its right to
         purchase such additional shares of Common Stock, the closing of such
         purchase shall occur at the same time as the closing of the initial
         public offering. DuPont shall have the right to purchase additional
         shares of Common Stock under this paragraph 2(c) only once, and after
         such initial purchase, its rights under this paragraph 2(c) shall
         terminate. Further provided that, in the event DuPont has exercised the
         share purchase option outlined in this paragraph 2(c), the provisions
         of paragraph 2(b) above shall not operate to allow DuPont to increase
         its ownership in excess of the 10% of "fully diluted" Common Stock of
         PCN specified above in this paragraph 2(c).

3.   DuPont's Obligations and Agreements.

    (a)  For the purposes of this paragraph 3, "Products" shall mean bulk
         chemicals, bulk polymers and refined oil products available for trade
         over the CheMatch system

    (b)  DuPont shall: (1) for a period of one year from the closing of the
         transactions contemplated by this letter agreement use the CheMatch
         platform of PCN at the standard rates charged for the use of the
         CheMatch platform exclusively for Products that it buys using
         e-commerce; (2) use reasonable efforts to use the



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          CheMatch platform of PCN at the standard rates charged for the use of
          the CheMatch platform for any Products that it trades; (3) for the
          four year period commencing 1 January 2001, use reasonable efforts to
          trade at the standard rates charged for the use of the CheMatch
          platform an increasing amount of spot purchases of Products provided
          that for the relevant Product CheMatch continues to serve as the
          marketplace for at least a reasonable quantity of such Product and
          such purchases continue to be in DuPont's economic interest; (4)
          assist PCN with the design of the CheMatch platform so that it becomes
          a more commercially desirable means of transacting business; and (5)
          provide PCN, at no cost to PCN, with a full time equivalent employee
          with knowledge of the relevant markets for a period of one year to
          work on increasing the volume of trading through the CheMatch
          platform.

     (c)  DuPont shall not invest in enterprises competing with PCN in the
          business of providing an on-line neutral marketplace with Product
          offerings which significantly overlap with those available through
          PCN, and specifically including without limitation ChemConnect, Inc.,
          and I to I Solutions Limited. Subject to the specific exclusion of
          ChemConnect, Inc., and I to I Solutions Limited, such prohibition
          shall not apply to investment by DuPont in enterprises in the business
          of providing an on-line neutral marketplace where DuPont's interest is
          to invest in such enterprises in order to enable DuPont to sell
          branded or specialty products. This provision shall remain in effect
          for the period during which DuPont or its affiliates maintain an
          equity interest in PCN, provided, however, that this provision shall
          remain in effect for at least one year from the date of the closing of
          the transactions contemplated by this letter agreement.

     (d)  DuPont shall provide PCN with a credit of $2 million towards the
          purchase of DuPont products and/or consulting services over a three
          year period from the closing of the Series C Preferred Stock
          Financing. The products and/or services shall include those related
          to market development, advertising, safety, health and environmental,
          logistics and other products or services as mutually agreed by the
          parties. Purchases of products shall be deducted from the $2 million
          total credit at list price less standard discount. Consulting
          services will be valued at $400 per hour. Additional services
          provided by DuPont may include without limitation items such as office
          space in international locations, attendance at trade conferences to
          provide testimonials or demonstrations of the CheMatch system,
          speaking at company or industry functions, trade shows or
          presentations to securities analysts.

4.   Additional Conditions.

     (a)  Subject to the execution of appropriate license agreements, DuPont
          will make available to CheMatch, for use on its site or through access
          to a DuPont Safety Resources site, certain safety, health and
          environmental information as agreed by the parties for a negotiated
          annual fee to be applied against the $2 million commitment pursuant to
          3(d) above to purchase DuPont products and services. Provided that
          the fee for any year is agreed by the parties, DuPont further agrees
          not to make such information available to ChemConnect, Inc. or
          E-Chemicals.




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     (b)  Provided that DuPont is in compliance with its obligations under
          paragraph 3, DuPont shall have the right to observe at PCN Board
          meetings so long as it owns 5% or more of PCN's Common Stock on a
          fully diluted basis (including Common Stock issuable on conversion of
          the Series C Preferred Stock warrants and options), but DuPont shall
          not be entitled to be present during any discussions relating to
          specific third party customers. DuPont shall give PCN notice prior to
          the date of the PCN Board meeting at which DuPont desires to have an
          observer. Such notice shall state the name of the observer and shall
          acknowledge that such observer is bound by confidentiality obligations
          to DuPont no less stringent than those set out in this letter
          agreement as a condition to the observer attending the PCN Board
          meeting.

     (c)  The securities which are the subject of this agreement have not been
          registered under the Securities Act of 1933, as amended, or applicable
          state securities laws. These securities have been acquired for
          investment and not with a view to distribution or resale, and may not
          be sold, mortgaged, pledged, hypothecated or otherwise transferred
          without an effective registration statement for such securities under
          the Securities Act of 1933, as amended, and applicable state
          securities laws, or the availability of an exemption from the
          registration provisions of the Securities Act of 1933 and applicable
          state securities laws. These securities will be further subject to any
          transfer restrictions imposed by the managing underwriter of the PCN
          initial public offering for such period following the PCN initial
          public offering as is determined by such managing underwriter.

     (d)  The parties agree to meet quarterly for a minimum period of two years
          to share ideas and recommendations on e-commerce strategies and site
          design as related to PCN's CheMatch platform and DuPont's e-commerce
          activities. There will be no consulting or other fees for those
          personnel participating in these quarterly sessions.

     (e)  DuPont and PCN shall use reasonable efforts to generate additional
          revenue streams for each other, which may include, for example,
          integration opportunities between PCN's CheMatch platform and DuPont's
          services.

     (f)  For a period of five years from the Closing of the transactions
          contemplated by this letter agreement, DuPont shall have the right of
          first negotiation to provide logistics, product testing and safety,
          health and environmental services or other services which are
          identified by DuPont to PCN as potential offerings. PCN shall be free
          to pursue with other parties any services which at such time are not
          identified by DuPont to PCN or which DuPont is not presently or at
          such time capable of delivering. Any such services provided by DuPont
          shall be at competitive rates and shall be subject to negotiation of
          definitive agreements.

5.   Confidentiality and Privacy.

     (a)  Both Parties shall maintain the confidentiality of each other's
          proprietary information pursuant to the confidentiality agreement
          between them dated October 19, 1999.

     (b)  PCN shall adopt a privacy policy no less comprehensive and with terms
          substantially similar to the then current terms of DuPont's privacy
          policy. DuPont shall not be obligated to provide information to PCN
          which is deemed


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          private under any applicable law, directive, statute, or regulation
          which would violate such law, directive, statue, or regulation
          provided that DuPont shall provide a copy of such policy to PCN and
          shall give notice of any changes in policies.

     (c)  Neither party may reference the other party to this agreement in
          presentations to third parties, advertising, promotions or other
          published information, unless such disclosure is required by law,
          without the other party's prior consent. Both parties may make
          disclosure of the existence of the DuPont investment in PCN in
          mutually agreed press releases provided that the detailed terms and
          conditions shall remain confidential unless required to be disclosed
          by law. Provided that, PCN and DuPont agree that they will issue a
          press release contemporaneous with the Series C Preferred Stock
          closing acknowledging and giving public notice of DuPont's inclusion
          as an investor in PCN, without giving specific details of the
          provisions of this agreement. Such press release is subject to mutual
          approval as to form and substance, which approval shall not be
          unreasonably withheld.

6.   Miscellaneous

     (a)  The Strategic Alliance, this letter agreement and all documentation
          contemplated by this letter shall be governed by the internal law of
          the State of Delaware, without regard to any conflict of laws
          principles.

     (b)  Each of PCN and DuPont will bear its own costs and expenses of the
          preparation of the documentation and performance of the obligations
          set forth in this letter.

     If this letter correctly sets forth our understanding, please indicate
your acceptance by executing this letter in the space provided below.

                                          Very truly yours,
                                          PETROCHEMNET HOLDINGS, INC.

                                          By: /s/ CARL D. MCCUTCHEON
                                              ----------------------------------
                                                  Carl D. McCutcheon
                                          President and Chief Executive Officer



ACCEPTED AND AGREED TO
THIS 12th day of November, 1999

E.I. duPont de Nemours and Company

By: /s/ J. ERIK FYRWALD
   --------------------
        J. ERIK FYRWALD



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