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                                                                   EXHIBIT 10.12

                              AMENDED AND RESTATED
                          REGISTRATION RIGHTS AGREEMENT


                                November 24, 1999


To each of the several Purchasers
(the "Purchasers") and the several DeWitt
Principals (as defined herein) listed on the signature
pages hereto

Ladies and Gentlemen:

         This will confirm that in consideration of (i) the purchase by Battery
Ventures V, L.P., Battery Investment Partners V LLC and Battery Ventures
Convergence Fund, L.P. (collectively, "Battery Ventures") pursuant to that
certain Preferred Stock and Warrant Purchase Agreement dated June 21, 1999 (the
"Initial Purchase Agreement") of (A) an aggregate of 2,138,400 Series A Units
(as defined in the Initial Purchase Agreement), comprised of an aggregate of
2,138,400 shares of Series A Convertible Preferred Stock (the "Series A
Preferred Stock") and the related Series A Warrants of PetroChemNet Holdings,
Inc., a Delaware corporation (the "Company") and (B) an aggregate of 2,032,200
Series B Units (as defined in the Initial Purchase Agreement), comprised of an
aggregate of 2,032,200 shares of Series B Convertible Preferred Stock (the
"Series B Preferred Stock") and the related Series B Warrants of the Company,
and (ii) the Purchasers' agreement on the date hereof to purchase, subject to
the terms and conditions set forth in that certain Preferred Stock and Warrant
Purchase Agreement dated on even date herewith (the "Series C Purchase
Agreement"), an aggregate of 3,503,169 Series C Units (as defined in the Series
C Purchase Agreement), comprised of an aggregate of 3,503,169 shares of Series C
Convertible Preferred Stock (the "Series C Preferred Stock") and the related
Series C Warrants of the Company, and as an inducement to the Purchasers to
enter into the Series C Purchase Agreement, and for other good and valuable
consideration the receipt and sufficiency of which are hereby acknowledged, the
Company covenants and agrees with each of the Purchasers as follows:

         1.       Certain Definitions. As used in this Agreement, the following
terms shall have the following respective meanings:

                  "CheMatch Reorganization Agreement" shall mean that certain
Agreement and Plan of Reorganization dated as of June 21, 1999 by and among
PetroChemNet Holdings, Inc., the Company, PCN Merger Sub and the DeWitt
Principals.

                  "Commission" shall mean the Securities and Exchange
Commission, or any other federal agency at the time administering the Securities
Act.


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         Amended and Restated Registration Rights Agreement -- Page 2


                  "Common Stock" shall mean the Common Stock, par value $.01 per
share, of the Company, as constituted as of the date of this Agreement.

                  "Conversion Shares" shall mean shares of Common Stock issued
or issuable upon conversion of the Purchased Shares and the Warrant Shares, and
any shares of capital stock received in respect thereof.

                  "Convertible Preferred Stock" shall mean the Series A
Convertible Preferred Stock, the Series B Convertible Preferred Stock and the
Series C Convertible Preferred Stock of the Company.

                  "DeWitt Principals" shall mean each of Earl H. Armstrong,
Teresa A. Acosta and William P. Barry.

                  "Exchange Act" shall mean the Securities Exchange Act of 1934
or any similar federal statute, and the rules and regulations of the Commission
thereunder, all as the same shall be in effect at the time.

                  "Preferred Stock Warrants" shall mean the Series A Preferred
Stock Purchase Warrants and the Series B Preferred Stock Purchase Warrants
issued to Battery Ventures pursuant to the Initial Purchase Agreement, and the
Series C Preferred Stock Purchase Warrants issued to the Purchasers pursuant to
the Series C Purchase Agreement.

                  "Purchased Shares" shall mean the shares of Series A Preferred
Stock and Series B Preferred Stock issued pursuant to the Initial Purchase
Agreement, and the shares of Series C Preferred Stock issued pursuant to the
Series C Purchase Agreement.

                  "Registrable Common Shares" shall mean (i) the shares of
Common Stock of the Company issued to the DeWitt Principals, Fred B. Cook and
Jorge A. Werlang in connection with the transactions contemplated by the
CheMatch Reorganization Agreement and (ii) the shares of Common Stock of the
Company issued upon the exercise or conversion of warrants issued to the DeWitt
Principals in connection with the transactions contemplated by the CheMatch
Reorganization Agreement.

                  "Registration Expenses" shall mean the expenses so described
in Section 8.

                  "Restricted Stock" shall mean the Conversion Shares and the
Registrable Common Shares, excluding Conversion Shares or Registrable Common
Shares which have been (a) registered under the Securities Act pursuant to an
effective registration statement filed thereunder and disposed of in accordance
with the registration statement covering them or (b) publicly sold pursuant to
Rule 144 under the Securities Act; provided, however, that for purposes of
Section 4(a) of this Agreement the term "Restricted Stock" shall not include the
Registrable Common Shares, and, accordingly,




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         Amended and Restated Registration Rights Agreement -- Page 3


the holders of the Registrable Common Shares shall not have any right to request
a registration pursuant to said Section 4(a).

                  "Securities Act" shall mean the Securities Act of 1933 or any
similar federal statute, and the rules and regulations of the Commission
thereunder, all as the same shall be in effect at the time.

                  "Selling Expenses" shall mean the expenses so described in
Section 8.

                  "Series B Convertible Preferred Stock" shall mean the shares
of Series B Convertible Preferred Stock of the Company.

                  "Warrant Shares" shall mean the shares of Convertible
Preferred Stock issuable or issued upon exercise of the Preferred Stock
Warrants.

         2.       Restrictive Legend. Each certificate representing Purchased
Shares, Conversion Shares or Restricted Stock shall, except as otherwise
provided in this Section 2 or in Section 3, be stamped or otherwise imprinted
with a legend substantially in the following form:

                  "The securities represented by this certificate have not been
registered under the Securities Act of 1933 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 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."

A certificate shall not bear such legend if in the opinion of counsel reasonably
satisfactory to the Company (it being agreed that Testa, Hurwitz & Thibeault,
LLP shall be satisfactory) the securities being sold thereby may be publicly
sold without registration under the Securities Act.

         3.       Notice of Proposed Transfer. Prior to any proposed transfer of
any Purchased Shares, Conversion Shares or Restricted Stock (other than under
the circumstances described in Sections 4, 5 or 6), the holder thereof shall
give written notice to the Company of its intention to effect such transfer.
Each such notice shall describe the manner of the proposed transfer and, if
requested by the Company, shall be accompanied by an opinion of counsel
reasonably satisfactory to the Company (it being agreed that Testa, Hurwitz &
Thibeault, LLP shall be satisfactory) to the effect that the proposed transfer
may be effected without registration under the Securities Act, whereupon the
holder of such stock shall be entitled to transfer such stock in accordance with
the terms of its notice; provided, however, that no such opinion of counsel
shall be required for a transfer to one or more partners of the transferor (in
the case of a transferor that is a partnership), to one or more members of the
transferor (in the case of a




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         Amended and Restated Registration Rights Agreement -- Page 4


transferor that is a limited liability company) or to an affiliated corporation
(in the case of a transferor that is a corporation); provided, further, however,
that any transferee other than a partner or affiliate of the transferor shall
execute and deliver to the Company a representation letter in form reasonably
satisfactory to the Company's counsel to the effect that the transferee is
acquiring Restricted Stock for its own account, for investment purposes and
without any view to distribution thereof. Each certificate for Purchased Shares
or Conversion Shares transferred as above provided shall bear the legend set
forth in Section 2, except that such certificate shall not bear such legend if
(i) such transfer is in accordance with the provisions of Rule 144 (or any other
rule permitting public sale without registration under the Securities Act) or
(ii) the opinion of counsel referred to above is to the further effect that the
transferee and any subsequent transferee (other than an affiliate of the
Company) would be entitled to transfer such securities in a public sale without
registration under the Securities Act. The restrictions provided for in this
Section 3 shall not apply to securities which are not required to bear the
legend prescribed by Section 2 in accordance with the provisions of that
Section. If the Company does not accept an opinion of counsel required hereby
signed by Testa, Hurwitz & Thibeault, LLP, the Company will pay the reasonable
fees and disbursements of other counsel in connection with all opinions rendered
by them pursuant to this Section 3.

         4.       Required Registration.

                  (a)      Subject to Section 13(f) of this Agreement, at any
time after the earlier of June 21, 2001 or the date that is six months after the
consummation of the Company's first underwritten public offering, (i) the
holders of Restricted Stock (excluding for purposes of this clause (i)
Conversion Shares relating to the Series C Preferred Stock) constituting at
least sixty percent (60%) in interest of the total shares of such Restricted
Stock then outstanding, taken together as a single class or (ii) the holders of
Restricted Stock relating to the Series C Preferred Stock constituting at least
sixty percent (60%) in interest of the total shares of such Restricted Stock
then outstanding, taken together as a single class, may request the Company to
register under the Securities Act all or any portion of the shares of Restricted
Stock held by such requesting holder or holders for sale in the manner specified
in such notice. For purposes of this Section 4 (unless otherwise specified
herein) and Sections 5, 6, 13(a) and 13(d), the term "Restricted Stock" shall be
deemed to include the number of shares of Restricted Stock which would be
issuable to a holder of Purchased Shares upon conversion of all shares of
Convertible Preferred Stock held by such holder at such time; provided, however,
that the only securities which the Company shall be required to register
pursuant hereto shall be shares of Common Stock; provided, further, however,
that, in any underwritten public offering contemplated by this Section 4 or
Sections 5 and 6, the holders of Purchased Shares shall be entitled to sell such
Purchased Shares to the underwriters for conversion and sale of the shares of
Common Stock issued upon conversion thereof. Notwithstanding anything to the
contrary contained herein, no request may be made under this Section 4 within
180 days after the effective date of a registration statement filed by the
Company covering a firm commitment underwritten public offering in which the
holders of Restricted Stock shall have been entitled to join pursuant to
Sections 5 or 6.


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         Amended and Restated Registration Rights Agreement -- Page 5


                  (b)      Following receipt of any notice under this Section 4,
the Company shall immediately notify all holders of Restricted Stock and
Purchased Shares from whom notice has not been received and such holders shall
then be entitled within 30 days thereafter to request the Company to include in
the requested registration all or any portion of their shares of Restricted
Stock. The Company shall use its best efforts to register under the Securities
Act, for public sale in accordance with the method of disposition described in
paragraph (a) above, the number of shares of Restricted Stock specified in such
notice (and in all notices received by the Company from other holders within 30
days after the giving of such notice by the Company). The Company shall be
obligated to register Restricted Stock pursuant to this Sections on two
occasions only for each class of holders specified in Section 4(a)(i) and
4(a)(ii); provided, however, that such obligation shall be deemed satisfied only
when a registration statement covering all shares of Restricted Stock specified
in notices received as aforesaid for sale in accordance with the method of
disposition specified by the requesting holders (i) shall have become effective
and, if such method of disposition is a firm commitment underwritten public
offering, all such shares shall have been sold pursuant thereto or (ii) if such
registration statement has been withdrawn prior to the consummation of the
offering at the request of the Investors (other than as a result of a material
adverse change in the business, prospects or condition, financial or otherwise,
of the Company).

                  (c)      The Company (or at the option of the Company, the
holders of Common Stock) shall be entitled to include in any registration
statement referred to in this Section 4, for sale in accordance with the method
of disposition specified by the requesting holders, shares of Common Stock to be
sold by the Company or such other holders for its own account, except as and to
the extent that, in the opinion of the managing underwriter (if such method of
disposition shall be an underwritten public offering), such inclusion would
adversely affect the marketing of the Restricted Stock to be sold. Except for
registration statements on Form S-4, S-8 or any successor thereto, the Company
will not file with the Commission any other registration statement with respect
to its Common Stock, whether for its own account or that of other stockholders,
from the date of receipt of a notice from requesting holders pursuant to this
Section 4 until the completion of the period of distribution of the registration
contemplated thereby.

                  (d)      If in the opinion of the managing underwriter the
inclusion of all of the Restricted Stock requested to be registered under this
Section would adversely affect the marketing of such shares, any Conversion
Shares to be sold by the holders of Restricted Stock shall be excluded only
after any Registrable Common Shares and shares to be sold by holders of Common
Stock other than the holders of Restricted Stock have been excluded, in such
manner that the shares to be sold shall be allocated among the selling holders
of the Conversion Shares pro rata based on their ownership of Restricted Stock.

         5.       Incidental Registration. Subject to Section 13(f) of this
Agreement, if the Company at any time (other than pursuant to Section 4 or
Section 6) proposes to register any of its securities under the Securities Act
for sale to the public, whether for its own



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         Amended and Restated Registration Rights Agreement -- Page 6



account or for the account of other security holders or both (except with
respect to registration statements on Forms S-4, S-8 or another form not
available for registering the Restricted Stock for sale to the public), each
such time it will give written notice to all holders of outstanding Restricted
Stock of its intention so to do. Upon the written request of any such holder,
received by the Company within 30 days after the giving of any such notice by
the Company, to register any of its Restricted Stock, the Company will use its
best efforts to cause the Restricted Stock as to which registration shall have
been so requested to be included in the securities to be covered by the
registration statement proposed to be filed by the Company, all to the extent
requisite to permit the sale or other disposition by the holder (in accordance
with its written request) of such Restricted Stock so registered. In the event
that any registration pursuant to this Section 5 shall be, in whole or in part,
an underwritten public offering of Common Stock, the number of shares of
Restricted Stock to be included in such an underwriting may be reduced (pro rata
among the requesting holders based upon the number of shares of Restricted Stock
held by such requesting holders) if and to the extent that the managing
underwriter shall be of the opinion that such inclusion would adversely affect
the marketing of the securities to be sold by the Company therein; provided,
however, that such number of shares of Restricted Stock shall not be reduced if
any shares are to be included in such underwriting for the account of any person
other than the Company or requesting holders of Restricted Stock; provided,
further, however, that in no event shall the number of shares of Restricted
Stock included in the offering be reduced below twenty percent (20%) of the
total number of shares of Common Stock included in such offering, unless the
offering is the Company's initial public offering of the Company's securities in
which case the number of shares of Restricted Stock to be included by the
holders may be reduced or eliminated entirely as set forth above.
Notwithstanding the foregoing provisions, the Company may withdraw any
registration statement referred to in this Section 5 without thereby incurring
any liability to the holders of Restricted Stock.

         6.       Registration on Form S-3. Subject to Section 13(f) of this
Agreement, if at any time (i) a holder or holders of Restricted Stock then
outstanding request that the Company file a registration statement on Form S-3
or any successor thereto for a public offering of all or any portion of the
shares of Restricted Stock held by such requesting holder or holders, provided
that the reasonably anticipated aggregate price to the public of such shares of
Restricted Stock equals or exceeds $1,000,000 and (ii) the Company is a
registrant entitled to use Form S-3 or any successor thereto to register such
shares, then the Company shall use its best efforts to register under the
Securities Act on Form S-3 or any successor thereto for public sale in
accordance with the method of disposition specified in such notice, the number
of shares of Restricted Stock specified in such notice. Whenever the Company is
required by this Section 6 to use its best efforts to effect the registration of
Restricted Stock, each of the procedures and requirements of Section 4
(including but not limited to the requirement that the Company notify all
holders of Restricted Stock from whom notice has not been received and provide
them with the opportunity to participate in the offering) shall apply to such
registration; provided, however, that there shall be no limitation on the number
of registrations on Form S-3 which may be requested and obtained under this
Section 6.

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         Amended and Restated Registration Rights Agreement -- Page 7


                  (b)      Notwithstanding anything to the contrary set forth in
this Agreement, the Company's obligation under this Agreement to register
Restricted Stock under the Securities Act on registration statements
("Registration Statements") may, upon the reasonable determination of the Board
of Directors made not more than twice in the aggregate (and not more than once
with respect to a Registration Statement on Form S-1 and not more than once with
respect to a Registration Statement on Form S-3) during any 12-month period, be
suspended in the event and during such period as unforeseen circumstances
(including without limitation (i) an underwritten primary offering by the
Company (which includes no secondary offering) if the Company is advised in
writing by its underwriters that the registration of the Restricted Stock would
have a material adverse effect on the Company's offering, or (ii) pending
negotiations relating to, or consummation of, a transaction or the occurrence of
an event which would require additional disclosure of material information by
the Company in Registration Statements or such other filings, as to which the
Company has a bona fide business purpose for preserving confidentiality or which
renders the Company unable to comply with Securities and Exchange Commission
(the "SEC") requirements) exist (such unforeseen circumstances being hereinafter
referred to as a "Suspension Event") which would make it impractical or
unadvisable for the Company to file the Registration Statements or such other
filings or to cause such to become effective. Such suspension shall continue
only for so long as such event is continuing but in no event for a period longer
than (i) one hundred and twenty (120) days, in the case of a Registration
Statement on Form S-1 (or any successor thereto) or (ii) ninety (90) days, in
the case of a Registration Statement on Form S-3 (or any successor thereto). The
Company shall notify the Purchasers of the existence and nature of any
Suspension Event.

         7.       Registration Procedures. If and whenever the Company is
required by the provisions of Sections 4, 5 or 6 to use its best efforts to
effect the registration of any shares of Restricted Stock under the Securities
Act, the Company will, as expeditiously as possible:

                  (a)      prepare and file with the Commission a registration
statement (which, in the case of an underwritten public offering pursuant to
Section 4, shall be on Form S-1 or other form of general applicability
satisfactory to the managing underwriter selected as therein provided) with
respect to such securities and use its best efforts to cause such registration
statement to become and remain effective for the period of the distribution
contemplated thereby (determined as hereinafter provided);

                  (b)      prepare and file with the Commission such amendments
and supplements to such registration statement and the prospectus used in
connection therewith as may be necessary to keep such registration statement
effective for the period specified in paragraph (a) above and comply with the
provisions of the Securities Act with respect to the disposition of all
Restricted Stock covered by such registration statement in accordance with the
sellers' intended method of disposition set forth in such registration statement
for such period;

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         Amended and Restated Registration Rights Agreement -- Page 8



                  (c)      furnish to each seller of Restricted Stock and to
each underwriter such number of copies of the registration statement and each
such amendment and supplement thereto (in each case including all exhibits) and
the prospectus included therein (including each preliminary prospectus) as such
persons reasonably may request in order to facilitate the public sale or other
disposition of the Restricted Stock covered by such registration statement;

                  (d)      use its best efforts to register or qualify the
Restricted Stock covered by such registration statement under the securities or
"blue sky" laws of such jurisdictions as the sellers of Restricted Stock or, in
the case of an underwritten public offering, the managing underwriter reasonably
shall request; provided, however, that the Company shall not for any such
purpose be required to qualify generally to transact business as a foreign
corporation in any jurisdiction where it is not so qualified or to consent to
general service of process in any such jurisdiction;

                  (e)      use its best efforts to list the Restricted Stock
covered by such registration statement with any securities exchange on which the
Common Stock of the Company is then listed;

                  (f)      immediately notify each seller of Restricted Stock
and each underwriter under such registration statement, at any time when a
prospectus relating thereto is required to be delivered under the Securities
Act, of the happening of any event of which the Company has knowledge as a
result of which the prospectus contained in such registration statement, as then
in effect, includes an untrue statement of a material fact or omits to state a
material fact required to be stated therein or necessary to make the statements
therein not misleading in light of the circumstances then existing, and promptly
prepare and furnish to such seller a reasonable number of copies of a prospectus
supplemented or amended so that, as thereafter delivered to the purchasers of
such Restricted Stock, such prospectus shall not include an untrue statement of
a material fact or omit to state a material fact required to be stated therein
or necessary to make the statements therein not misleading in light of the
circumstances then existing;

                  (g)      if the offering is underwritten and at the request of
any seller of Restricted Stock, use its best efforts to furnish on the date that
Restricted Stock is delivered to the underwriters for sale pursuant to such
registration: (i) an opinion dated such date of counsel representing the Company
for the purposes of such registration, addressed to the underwriters and to such
seller, to such effect as reasonably may be requested by counsel for the
underwriters, and (ii) a letter dated such date from the independent public
accountants retained by the Company, addressed to the underwriters and to such
seller, stating that they are independent public accountants within the meaning
of the Securities Act and that, in the opinion of such accountants, the
financial statements of the Company included in the registration statement or
the prospectus, or any amendment or supplement thereof, comply as to form in all
material respects with the applicable accounting requirements of the Securities
Act, and such letter shall additionally cover such other financial matters
(including information as to the period



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         Amended and Restated Registration Rights Agreement -- Page 9


ending no more than five business days prior to the date of such letter) with
respect to such registration as such underwriters reasonably may request;

                  (h)      make available for inspection by each seller of
Restricted Stock, any underwriter participating in any distribution pursuant to
such registration statement, and any attorney, accountant or other agent
retained by such seller or underwriter, reasonable access to all financial and
other records, pertinent corporate documents and properties of the Company, as
such parties may reasonably request, and cause the Company's officers, directors
and employees to supply all information reasonably requested by any such seller,
underwriter, attorney, accountant or agent in connection with such registration
statement;

                  (i)      cooperate with the selling holders of Restricted
Stock and the managing underwriters, if any, to facilitate the timely
preparation and delivery of certificates representing Restricted Stock to be
sold, such certificates to be in such denominations and registered in such names
as such holders or the managing underwriters may request at least two business
days prior to any sale of Restricted Stock; and

                  (j)      permit any holder of Restricted Stock which holder,
in the sole and exclusive judgment, exercised in good faith, of such holder,
might be deemed to be a controlling person of the Company, to participate in
good faith in the preparation of such registration or comparable statement and
to require the insertion therein of material, furnished to the Company in
writing, which in the reasonable judgment of such holder and its counsel should
be included.

                  For purposes of Section 7(a) and 7(b) and of Section 4(c), (i)
the period of distribution of Restricted Stock in a firm commitment underwritten
public offering shall be deemed to extend until each underwriter has completed
the distribution of all securities purchased by it, and (ii) the period of
distribution of Restricted Stock in any other registration shall be deemed to
extend until the earlier of the sale of all Restricted Stock covered thereby and
90 days after the effective date thereof; provided, however, that the period
referred to in this clause (ii) shall be extended by one day for each day that
the Company's obligations are suspended under Section 6(b) in connection with a
Suspension Event and for each day that the holders of Restricted Stock are
unable to sell their shares of Restricted Stock upon the happening of an event
as a result of which the prospectus contained in such registration statement, as
then in effect, includes an untrue statement of material fact or omits to state
a material fact required to be stated therein (subject to a maximum period under
this clause (ii) of 180 days).

                  In connection with each registration hereunder, the sellers of
Restricted Stock will furnish to the Company in writing such information
requested by the Company with respect to themselves and the proposed
distribution by them as reasonably shall be necessary in order to assure
compliance with federal and applicable state securities laws and to make the
registration statement correct, accurate and complete in all respects with
respect to such sellers; provided, however, that this requirement shall not be
deemed to


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         Amended and Restated Registration Rights Agreement -- Page 10


limit any disclosure obligation arising out of any seller's relationship to the
Company if one of such seller's agents or affiliates is an officer, director or
control person of the Company. In addition, the sellers shall, if requested by
the Company, execute such other agreements, which are reasonably satisfactory to
them and which shall contain such provisions as may be customary and reasonable
in order to accomplish the registration of the Restricted Stock.

                  In connection with each registration pursuant to Sections 4, 5
or 6 covering an underwritten public offering, the Company and each seller agree
to enter into a written agreement with the managing underwriter selected in the
manner herein provided in such form and containing such provisions as are
customary in the securities business for such an arrangement between such
underwriter and companies of the Company's size and investment stature.

         8.       Expenses. All expenses incurred by the Company in complying
with Sections 4, 5 and 6, including, without limitation, all registration and
filing fees, printing expenses, fees and disbursements of counsel and
independent public accountants for the Company, fees and expenses (including
counsel fees) incurred in connection with complying with state securities or
"blue sky" laws, fees and expenses of one outside counsel for the selling
holders of Restricted Stock in connection with the registration of Restricted
Stock, fees of the National Association of Securities Dealers, Inc., transfer
taxes, fees of transfer agents and registrars, costs of any insurance which
might be obtained, but excluding any Selling Expenses, are called "Registration
Expenses." All underwriting discounts and selling commissions applicable to the
sale of Restricted Stock and the fees and expenses of more than one counsel for
the selling holders of Restricted Stock in connection with the registration of
Restricted Stock are called "Selling Expenses."

                  The Company will pay all Registration Expenses in connection
with each registration statement under Sections 4, 5 or 6. All Selling Expenses
in connection with each registration statement under Sections 4, 5 or 6 shall be
borne by the participating sellers in proportion to the number of shares sold by
each, or by such participating sellers other than the Company (except to the
extent the Company shall be a seller) as they may agree.

         9.       Indemnification.

                  (a)      In the event of a registration of any of the
Restricted Stock under the Securities Act pursuant to Sections 4, 5 or 6, the
Company will indemnify and hold harmless each holder of Restricted Stock, its
officers and directors, each underwriter of such Restricted Stock thereunder and
each other person, if any, who controls such seller or underwriter within the
meaning of the Securities Act, against any losses, claims, damages or
liabilities, joint or several, to which such holder, officer, director,
underwriter or controlling person may become subject under the Securities Act or
otherwise, insofar as such losses, claims, damages or liabilities (or actions in
respect thereof) arise out of or are based upon (i) any untrue statement or
alleged untrue statement of any material fact

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         Amended and Restated Registration Rights Agreement -- Page 11



contained in any registration statement under which such Restricted Stock was
registered under the Securities Act pursuant to Sections 4, 5 or 6, any
preliminary prospectus or final prospectus contained therein, or any amendment
or supplement thereof, (ii) any blue sky application or other document executed
by the Company specifically for that purpose or based upon written information
furnished by the Company filed in any state or other jurisdiction in order to
qualify any or all of the Restricted Stock under the securities laws thereof
(any such application, document or information herein called a "Blue Sky
Application"), (iii) the omission or alleged omission to state therein a
material fact required to be stated therein or necessary to make the statements
therein not misleading, (iv) any violation by the Company or its agents of any
rule or regulation promulgated under the Securities Act applicable to the
Company or its agents and relating to action or inaction required of the Company
in connection with such registration, or (v) any failure to register or qualify
the Restricted Stock in any state where the Company or its agents has
affirmatively undertaken or agreed in writing that the Company (the undertaking
of any underwriter chosen by the Company being attributed to the Company) will
undertake such registration or qualification on the seller's behalf (provided
that in such instance the Company shall not be so liable if it has undertaken
its best efforts to so register or qualify the Restricted Stock) and will
reimburse each such holder, and such officer and director, each such underwriter
and each such controlling person for any legal or other expenses reasonably
incurred by them in connection with investigating or defending any such loss,
claim, damage, liability or action; provided, however, that the Company will not
be liable in any such case if and to the extent that any such loss, claim,
damage or liability arises out of or is based upon an untrue statement or
alleged untrue statement or omission or alleged omission so made in conformity
with information furnished by any such seller, any such underwriter or any such
controlling person in writing specifically for use in such registration
statement or prospectus.

                  (b)      In the event of a registration of any of the
Restricted Stock under the Securities Act pursuant to Sections 4, 5 or 6, each
seller of such Restricted Stock thereunder, severally and not jointly, will
indemnify and hold harmless the Company, each person, if any, who controls the
Company within the meaning of the Securities Act, each officer of the Company
who signs the registration statement, each director of the Company, each other
holder of Restricted Stock, each underwriter and each person who controls any
underwriter within the meaning of the Securities Act, against all losses,
claims, damages or liabilities, joint or several, to which the Company or such
officer, director, other seller, underwriter or controlling person may become
subject under the Securities Act or otherwise, insofar as such losses, claims,
damages or liabilities (or actions in respect thereof) arise out of or are based
upon any untrue statement or alleged untrue statement of any material fact
contained in the registration statement under which such Restricted Stock was
registered under the Securities Act pursuant to Sections 4, 5 or 6, any
preliminary prospectus or final prospectus contained therein, or any amendment
or supplement thereof, or any Blue Sky Application or arise out of or are based
upon the omission or alleged omission to state therein a material fact required
to be stated therein or necessary to make the statements therein not misleading,
and will reimburse the Company and each such officer, director, other seller,
underwriter and controlling person for any legal or other expenses reasonably
incurred by them in connection with


                                       11
<PAGE>   12
         Amended and Restated Registration Rights Agreement -- Page 12



investigating or defending any such loss, claim, damage, liability or action;
provided, however, that such seller will be liable hereunder in any such case if
and only to the extent that any such loss, claim, damage or liability arises out
of or is based upon an untrue statement or alleged untrue statement or omission
or alleged omission made in reliance upon and in conformity with information
pertaining to such seller, as such, furnished in writing to the Company by such
seller specifically for use in such registration statement or prospectus; and
provided, further, however, that the liability of each seller hereunder shall be
limited to the proportion of any such loss, claim, damage, liability or expense
which is equal to the proportion that the public offering price of the shares
sold by such seller under such registration statement bears to the total public
offering price of all securities sold thereunder, but not in any event to exceed
the proceeds received by such seller from the sale of Restricted Stock covered
by such registration statement.

                  (c)      Promptly after receipt by an indemnified party
hereunder of notice of the commencement of any action, such indemnified party
shall, if a claim in respect thereof is to be made against the indemnifying
party hereunder, notify the indemnifying party in writing thereof, but the
omission so to notify the indemnifying party shall not relieve it from any
liability which it may have to such indemnified party other than under this
Section 9 and shall only relieve it from any liability which it may have to such
indemnified party under this Section 9 if and to the extent the indemnifying
party is prejudiced by such omission. In case any such action shall be brought
against any indemnified party and it shall notify the indemnifying party of the
commencement thereof, the indemnifying party shall be entitled to participate in
and, to the extent it shall wish, to assume and undertake the defense thereof
with counsel satisfactory to such indemnified party, and, after notice from the
indemnifying party to such indemnified party of its election so to assume and
undertake the defense thereof, the indemnifying party shall not be liable to
such indemnified party under this Section 9 for any legal expenses subsequently
incurred by such indemnified party in connection with the defense thereof other
than reasonable costs of investigation and of liaison with counsel so selected;
provided, however, that, if the defendants in any such action include both the
indemnified party and the indemnifying party and the indemnified party shall
have reasonably concluded that the interests of the indemnified party reasonably
may be deemed to conflict with the interests of the indemnifying party, the
indemnified party shall have the right to select a separate counsel and to
assume such legal defenses and otherwise to participate in the defense of such
action, with the expenses and fees of such separate counsel and other expenses
related to such participation to be reimbursed by the indemnifying party as
incurred.

                  (d)      The indemnities provided in this Section 9 shall
survive the transfer of any Restricted Stock by such holder.

         10.      Changes in Common Stock or Convertible Preferred Stock. If,
and as often as, there is any change in the Common Stock or the Convertible
Preferred Stock by way of a stock split, stock dividend, combination or
reclassification, or through a merger, consolidation, reorganization or
recapitalization, or by any other means, appropriate


                                       12
<PAGE>   13


         Amended and Restated Registration Rights Agreement -- Page 13

adjustment shall be made in the provisions hereof so that the rights and
privileges granted hereby shall continue with respect to the Common Stock or the
Convertible Preferred Stock as so changed.

         11.      Rule 144 Reporting. With a view to making available the
benefits of certain rules and regulations of the Commission which may at any
time permit the sale of the Restricted Stock to the public without registration,
at all times after 90 days after any registration statement covering a public
offering of securities of the Company under the Securities Act shall have become
effective, the Company agrees to:

                  (a)      make and keep public information available, as those
terms are understood and defined in Rule 144 under the Securities Act;

                  (b)      use its best efforts to file with the Commission in a
timely manner all reports and other documents required of the Company under the
Securities Act and the Exchange Act; and

                  (c)      furnish to each holder of Restricted Stock forthwith
upon request a written statement by the Company as to its compliance with the
reporting requirements of such Rule 144 and of the Securities Act and the
Exchange Act, a copy of the most recent annual or quarterly report of the
Company, and such other reports and documents so filed by the Company as such
holder may reasonably request in availing itself of any rule or regulation of
the Commission allowing such holder to sell any Restricted Stock without
registration.

         12.      Representations and Warranties of the Company. The Company
represents and warrants to you as follows:

                  (a)      The execution, delivery and performance of this
Agreement by the Company have been duly authorized by all requisite corporate
action and will not violate any provision of law, any order of any court or
other agency of government, the articles of organization or Bylaws of the
Company or any provision of any indenture, agreement or other instrument to
which it or any or its properties or assets is bound, conflict with, result in a
breach of or constitute (with due notice or lapse of time or both) a default
under any such indenture, agreement or other instrument or result in the
creation or imposition of any lien, charge or encumbrance of any nature
whatsoever upon any of the properties or assets of the Company.

                  (b)      This Agreement has been duly executed and delivered
by the Company and constitutes the legal, valid and binding obligation of the
Company, enforceable in accordance with its terms, except to the extent the
indemnification provisions herein may be deemed not enforceable.


                                       13
<PAGE>   14
         Amended and Restated Registration Rights Agreement -- Page 14



         13.      Miscellaneous.

                  (a)      All covenants and agreements contained in this
Agreement by or on behalf of any of the parties hereto shall bind and inure to
the benefit of the respective successors and assigns of the parties hereto
(including without limitation transferees of any Purchased Shares or Restricted
Stock), whether so expressed or not; provided, however, that registration rights
conferred herein on the holders of Purchased Shares or Restricted Stock shall
only inure to the benefit of a transferee of Purchased Shares or Restricted
Stock if (i) there is transferred to such transferee at least ten percent (10%)
of the shares of Restricted Stock (appropriately adjusted for any subdivision or
combination) originally issued pursuant to the Initial Purchase Agreement or the
Series C Purchase Agreement, as the case may be, to the direct or indirect
transferor of such transferee or (ii) such transferee is a partner, shareholder
or affiliate of a party hereto.

                  (b)      All notices, requests, consents and other
communications hereunder shall be in writing and shall be mailed by certified or
registered mail, return receipt requested, postage prepaid, or telexed, in the
case of non-U.S. residents, addressed as follows:

                  if to the Company or any other party hereto, at the address of
such party set forth in the Initial Purchase Agreement or the Series C Purchase
Agreement, as the case may be, or in a certain Stockholders Agreement by and
among the parties hereto (other than Jorge A. Werlang) dated as of the date
hereof with a copy to the Company's counsel as indicated therein, or as to Mr.
Werlang, at his address as set forth in the Termination and Settlement Agreement
to which he is party with the Company and CheMatch, Inc.;

                  if to any subsequent holder of Purchased Shares or Restricted
Stock, to it at such address as may have been furnished to the Company in
writing by such holder;

or, in any case, at such other address or addresses as shall have been furnished
in writing to the Company (in the case of a holder of Purchased Shares or
Restricted Stock) or to the holders of Purchased Shares or Restricted Stock (in
the case of the Company) in accordance with the provisions of this paragraph.

                  (c)      This Agreement shall be construed and enforced in
accordance with and governed by the General Corporation Law of the State of
Delaware.

                  (d)      This Agreement constitutes the entire agreement among
the parties with respect to the subject matter hereof and supersedes all prior
agreements and understandings between them or any of them as to such subject
matter; provided, however, that with respect to the parties to the Initial
Purchase Agreement, this Agreement shall be effective insofar as the Series A
Units and Series B Units are concerned only upon the closing of the Series C
Purchase Agreement at which time the Registration Rights Agreement, dated June
21, 1999, among the Company, Battery Ventures and the other parties named
therein shall be null and void and of no further effect.

                                       14
<PAGE>   15

         Amended and Restated Registration Rights Agreement -- Page 15


                  (e)      This Agreement may not be amended or modified, and no
provision hereof may be waived, without the written consent of the Company and
the holders of at least 66% of the outstanding shares of Restricted Stock held
by the Investors (excluding any shares of the Convertible Preferred Stock issued
pursuant to the exercise of Preferred Stock Warrants issued pursuant to the
Initial Purchase Agreement or the Series C Purchase Agreement) and at least 66%
of the outstanding shares of Restricted Stock held by non-Investors.
Notwithstanding the foregoing, no such amendment or modification shall be
effective if and to the extent that such amendment or modification either (a)
creates any additional affirmative obligations to be complied with by any or all
of the Purchasers or (b) grants to any one or more Purchasers any rights more
favorable than any rights granted to all other Purchasers or otherwise treats
any one or more Purchasers differently than all other Purchasers.

                  (f)      This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

                  (g)      The obligations of the Company to register shares of
Restricted Stock under Sections 4, 5 or 6 shall terminate four (4) years after
completion of an underwritten public offering of shares of Common Stock in which
the net proceeds received by the Company shall be at least $25 million and the
per share price paid by the public for such shares shall be at least $15.70 per
share (appropriately adjusted to reflect any subdivision, combination or the
like).

                  (h)      If requested in writing by the underwriters for the
initial underwritten public offering of securities of the Company, each holder
of Restricted Stock who is a party to this Agreement shall agree not to sell
publicly any shares of Restricted Stock or any other shares of Common Stock
(other than shares of Restricted Stock or other shares of Common Stock being
registered in such offering), without the consent of such underwriters, for a
period of not more than 180 days following the consummation of such initial
public offering; provided, however, that all persons entitled to registration
rights with respect to shares of Common Stock who are not parties to this
Agreement and all executive officers and directors of the Company shall also
have agreed not to sell publicly their Common Stock under the circumstances and
pursuant to the terms set forth in this Section 13(h).

                  (i)      The Company shall not grant to any third party any
registration rights comparable to or more favorable than any of those contained
herein without the prior written consent of holders holding more than 66% of the
Restricted Stock, so long as the Purchasers shall own at least 50% of the
Restricted Stock.

                  (j)      If any provision of this Agreement shall be held to
be illegal, invalid or unenforceable, such illegality, invalidity or
unenforceability shall attach only to such provision and shall not in any manner
affect or render illegal, invalid or unenforceable any other provision of this
Agreement, and this Agreement shall be carried out as if any such illegal,
invalid or unenforceable provision were not contained herein.

                                       15
<PAGE>   16

         Amended and Restated Registration Rights Agreement -- Page 16











                  [Remainder of page intentionally left blank.]





                                       16
<PAGE>   17

         Amended and Restated Registration Rights Agreement -- Page 17



                  Please indicate your acceptance of the foregoing by signing
and returning the enclosed counterpart of this letter, whereupon this Agreement
shall be a binding agreement between the Company and you.

                                  Very truly yours,


                                  PETROCHEMNET HOLDINGS, INC.


                                  By:  /s/ LARRY MCAFEE
                                      ---------------------------
                                  Name: Larry McAfee
                                  Title:

AGREED TO AND ACCEPTED as of
the date first above written.


EARL H. ARMSTRONG                                 TERESA A. ACOSTA

/s/ EARL H. ARMSTRONG                             /s/ TERESA A. ACOSTA
------------------------------                    ------------------------------


WILLIAM P. BARRY                                  FRED B. COOK

/s/ WILLIAM P. BARRY                              /s/ FRED B. COOK
------------------------------                    ------------------------------


JORGE A. WERLANG

/s/ JORGE A. WERLANG
------------------------------



                                       17
<PAGE>   18


         Amended and Restated Registration Rights Agreement -- Page 18


PURCHASERS:

SPROUT CAPITAL VIII, L.P.
By: DLJ Capital Corp.,
    its managing general partner

By: /s/ JANET A. HICKEY
   -------------------------
Name: Janet A. Hickey
Title: Senior Vice President

SPROUT VENTURE CAPITAL, L.P.
By: DLJ Capital Corp.,
    its general partner

By: /s/ JANET A. HICKEY
   -------------------------
Name: Janet A. Hickey
Title: Senior Vice president

DLJ ESC II, L.P.
By: DLJ LBO Plans Management Corporation,
    its general partner

By: /s/ JANET A. HICKEY
   -------------------------
Name: Janet A. Hickey
Title: Attorney in-fact

DLJ CAPITAL CORP.

By: /s/ JANET A. HICKEY
   -------------------------
Name: Janet A. Hickey
Title: Senior Vice president

MARQUETTE VENTURE PARTNERS III, L.P.
By: Marquette III, L.L.C.

By: /s/ [ILLEGIBLE]
   -------------------------
Name:
Title:

E. I. DUPONT DE NEMOURS AND COMPANY

By: /s/ JON ERIK FRYWALD
   -------------------------
Name: Jon Erik Frywald
Title: Vice President e-Commerce



                                       18
<PAGE>   19

         Amended and Restated Registration Rights Agreement -- Page 19



BATTERY VENTURES V, L.P.
By: Battery Partners V, LLC

By: /s/ OLIVER D. CURME
   -------------------------
      Member Manager

BATTERY INVESTMENT PARTNERS V LLC

By: /s/ OLIVER D. CURME
   -------------------------
      Member Manager

BATTERY VENTURES CONVERGENCE FUND, L.P.
By: Battery Convergence Partners, LLC

By: /s/ OLIVER D. CURME
   -------------------------
Name: Oliver D. Curme
Title:

STOLT-NIELSEN TRANSPORTATION GROUP LTD.

By: /s/ JAN CHR. ENGELHARDSTEN
   ---------------------------
Name: Jan Chr. Engelhardsten
Title: Chief Financial Officer

MILLENIUM HOLDINGS INC.

By: /s/ GEORGE H. HEMPSTEAD
   -------------------------
Name: George H. Hempstead
Title: Senior Vice President

/s/ DON CHURCHMAN
-------------------------
Don Churchman

/s/ CHRIS DAVIS
-------------------------
Chris Davis

/s/ ROGER LEEDY
-------------------------
Roger Leedy

/s/ LARRY MCAFEE
-------------------------
Larry McAfee

/s/ CARL MCCUTCHEON
-------------------------
Carl McCutcheon

/s/ JIM RAHE
-------------------------
Jim Rahe

/s/ JOHN SHARUM
-------------------------
John Sharum

/s/ GERRY ELIAS
-------------------------
Gerry Elias







                                       19