1 							 							Exhibit 2.1 	ASSIGNMENT AND ASSUMPTION AGREEMENT, dated as of October 4, 1996 	(the "Agreement"), among Clark Refining & Marketing, Inc. ("Assignor"), 	a Delaware corporation, J. ARON & COMPANY ("Assignee"), a New York 	partnership, Clark USA, Inc. ("Clark USA"), a Delaware corporation, 	and, solely for the limited purposes of Sections 4.06, 4.08, 4.10 and 	4.12(a) hereof and no other, each of Occidental Petroleum Corporation 	("OPC"), a Delaware corporation, Occidental C.O.B. Partners ("OCP"), 	a Delaware general partnership, and Occidental Crude Sales, Inc. 	(International) ("OCS") , a Delaware corporation. 	WHEREAS, the Assignor is a party to certain agreements set forth on 	Annex A and it desires to assign to Assignee, and Assignee desires 	to assume from Assignor, such agreements. 	WHEREAS, the Assignor acquired such agreements from Clark USA pursuant 	to an Assignment and Assumption Agreement dated as of October 3, 1996 	between Clark USA and Assignor (the "USA Assignment" and, together with 	this Agreement, the "Agreements"). 	NOW THEREFORE, in consideration of the foregoing and the respective 	representations, warranties, covenants and agreements set forth in this 	Agreement, the parties agree as follows: 				 I. ASSIGNMENT AND ASSUMPTION 	SECTION 1.01. Assignment and Assumption. (a) For and in consideration 	of the Purchase Price (as defined below) the receipt whereof is hereby 	acknowledged by the Assignor, the Assignor does hereby sell, assign and 	transfer to the Assignee, effective as of 11:59 p.m. (the "Effective 	Time") on October 3, 1996 (the "Effective Date"), all of the Assignor's 	right, title and interest (i) in the agreements listed on Annex A annexed 	hereto (hereinafter referred to, individually and collectively, as the 	"Instruments") and (ii) in the USA Assignment. 	(b) The Assignee does hereby, for the benefit of the Assignor and the 	other parties to the Instruments, accept this assignment and expressly 	assume and agree to hereafter perform, observe and abide by all of the 	terms, covenants, conditions and obligations under the Instruments on the 	part of the Assignor to be kept, observed and performed thereunder, and 	the Assignee does hereby agree to defend and indemnify the Assignor, and 	save the Assignor and its successors harmless, of and from any and all 	demands, claims, actions or causes of action, assessments, expenses, 	costs, damages, losses and liabilities, including reasonable attorneys' 	fees and disbursements, that the Assignor or the Assignor's successors 	may sustain or incur as a result of the failure of the Assignee, or 2 	 	those claiming under or through the Assignee, from and after the 	Effective Time on the Effective Date, to keep, observe and perform any 	of the terms, covenants, conditions and obligations under the 	Instruments that are to be observed or performed from and after the 	Effective Time. 	SECTION 1.02. Purchase Price. The "Purchase Price" is $235,400,000.00 	in immediately available funds delivered by wire transfer to an account 	designated by Assignor. 		 II. REPRESENTATIONS AND WARRANTIES OF ASSIGNOR 	As an inducement to Assignee to enter into this Agreement, each of 	Assignor and Clark USA hereby represents and warrants to Assignee as of 	the Effective Time on the Effective Date as follows (such 	representations and warranties to survive (i) for a period of six 	months after the Effective Time on the Effective Date in the case of 	Sections 2.01, 2.02, 2.03, 2.04 and 2.06, and (ii) into perpetuity in 	the case of Section 2.05) (provided, however, that the representations 	and warranties made by Assignor with respect to Sections 2.01, 2.02, 	2.03 and 2.04 are made only with respect to itself): 	SECTION 2.01. Organization and Authority of Assignor. Each of 	Assignor and Clark USA is a corporation duly organized, validly existing 	and in good standing under the laws of Delaware and has all necessary 	power and authority to enter into this Agreement and the USA Agreement, 	to carry out its obligations hereunder and thereunder and to consummate 	the transactions contemplated hereby and thereby. The execution and 	delivery of each of the Agreements by Assignor and Clark USA, the 	performance by Assignor and Clark USA of its obligations under the 	Agreements and the consummation by Assignor and Clark USA of the 	transactions contemplated by the Agreements have been duly authorized 	by all requisite action on the part of Assignor and Clark USA. Each 	Agreement has been duly executed and delivered by Assignor and Clark 	USA, and (assuming due authorization, execution and delivery by the 	other parties hereto in the case of this Agreement) each Agreement 	constitutes legal, valid and binding obligations of Assignor and Clark 	USA enforceable against Assignor and Clark USA in accordance with its 	terms. 	SECTION 2.02. No Conflict. The execution, delivery and performance 	of the Agreements by Assignor and Clark USA does not and will not (a) 	violate, conflict with or result in the breach of any provision of the 	certificate of incorporation or by-laws of Assignor or Clark USA, (b) 	conflict with or violate any law or governmental order applicable to 	Assignor or Clark USA, or (c) conflict with, result in any breach of, 	constitute a default (or event which with the giving of notice or lapse 	of time, or both, would become a default) under, require any consent 	under, or give to others any rights of termination, 	 3 	 	amendment, acceleration, suspension, revocation or cancellation of any 	of the Instruments or of any other agreement binding on or affecting 	Assignor or Clark USA or any of either of their assets. 	SECTION 2.03. No Default. Each of the Instruments to which Assignor 	or Clark USA is a party is in full force and effect and is Assignor's 	or Clark USA's, as applicable, legal, valid and binding obligation, 	enforceable against Assignor or Clark USA, as applicable, in accordance 	with the terms thereof. To Assignor's and Clark USA's best knowledge, no 	party to an Instrument is in default thereunder or has breached any 	terms or provisions thereof. No third party has given Assignor or Clark 	USA notice of any claim, dispute or controversy with respect to any of 	the Instruments nor has Assignor or Clark USA received notice of alleged 	nonperformance, or other noncompliance by Assignor or Clark USA with 	respect to Assignor's and Clark USA's obligations under any of the 	Instruments. Neither Assignor or Clark USA is in default under any of 	the Instruments or has breached any terms or provisions thereof. The 	Instruments have not been amended or supplemented by agreement, course 	of conduct or otherwise, other than (i) by the Agreements, (ii) the 	reports and notices referenced in Section 2.06 hereof and (iii) notices 	delivered to Clark USA in connection with the matters referred to in 	Section 4.08 and no waivers have been granted thereunder. There are no 	other agreements or instruments that vary the terms of any of the 	Instruments. Attached hereto as Annex B are true, correct and complete 	copies of the Instruments. 	SECTION 2.04. Title; No Liens (a) Immediately prior to the 	Effective Time on the Effective Date, Assignor had good and marketable 	title to each of the Instruments free and clear of any liens, claims 	or encumbrances of any kind (each, a "Lien"), including but not limited 	to any Lien of Universal Exchange Corporation ("UEC"), and the Assignor 	is hereby transferring to the Assignee pursuant to this Agreement, good 	and marketable title to each of the Instruments free and clear of any 	Liens. 	(b) Immediately prior to the execution and delivery of the USA 	Assignment, Clark USA had good and marketable title to each of the 	Instruments free and clear of any Liens, including but not limited to 	any Lien of UEC, and by executing and delivering the USA Assignment 	Clark USA transferred to Assignor good and marketable title to each of 	the Instruments free and clear of any Liens. 	SECTION 2.05. Delivery of Crude Oil. As of August 31, 1996, 1,452,000 	barrels (in barrels of WTI) will have been delivered under the 	Instruments at an average WTI Reference Price of $20.03 per barrel 	(after deduction of the marketing fee of $0.25 per barrel) 4 	 	SECTION 2.06. Reports and Information. Attached hereto as Annex C are 	true, correct and complete copies of all reports and notices furnished 	to Assignor or Clark USA in connection with the Instruments. The 	Assignor has no reason to believe that such information is not accurate 	in all material respects. 		 III. REPRESENTATIONS AND WARRANTIES OF ASSIGNEE 	As an inducement to Assignor and Clark USA to enter into this 	Agreement, Assignee hereby represents and warrants to Assignor and Clark 	USA as of the Effective Time on the Effective Date as follows (such 	representations and warranties to survive for a period of six months 	after the Effective Time on the Effective Date): 	SECTION 3.01. Organization and Authority of Assignee. Assignee is a 	partnership duly organized, validly existing and in good standing under 	the laws of the State of New York and has all necessary power and 	authority to enter into this Agreement, to carry out its obligations 	hereunder and to consummate the transactions contemplated hereby. The 	execution and delivery of this Agreement by Assignee, the performance 	by Assignee of its obligations hereunder and the consummation by 	Assignee of the transactions contemplated hereby have been duly 	authorized by all requisite action on the part of Assignee. This 	Agreement has been duly executed and delivered by Assignee and 	(assuming due authorization, execution and delivery by the other parties 	hereto) this Agreement constitutes legal, valid and binding obligations 	of Assignee, enforceable against Assignee in accordance with its terms. 	SECTION 3.02. No Conflict. The execution, delivery and performance of 	this Agreement by Assignee do not and will not (a) violate, conflict 	with or result in the breach of any provision of the partnership 	agreement or organizational documents of Assignee or (b) conflict with 	or violate any law or governmental order applicable to Assignee. 	SECTION 3.03. Assignee Business. Assignee is not, and is not an 	affiliate of, one of the twenty (20) largest international oil 	companies, as measured by revenue, as of the most recent calendar year 	for which such information is available. 				 IV. MISCELLANEOUS 	SECTION 4.01. Expenses. Except as otherwise specified in this 	Agreement, all costs and expenses, including, without limitation, fees 	and disbursements of counsel, financial advisors and accountants, 	incurred in connection with this 5 	 	Agreement and the transactions contemplated hereby shall be paid 	by the party incurring such costs and expenses. 	SECTION 4.02. Notices. All notices, requests, claims, demands and 	other communications hereunder shall be in writing and shall be given 	or made (and shall be deemed to have been duly given or made upon 	receipt) by delivery in person, by courier service, by facsimile, or 	by registered or certified mail (postage prepaid, return receipt 	requested) to the parties at the following addresses (or at such other 	address for a party as shall be specified in a notice given in 	accordance with this Section 4.02): 	(a) if to Assignor: 		Clark Refining & Marketing, Inc. 		8182 Maryland Avenue 		St. Louis, Missouri 63105-3721 		Attn: Maura Clark 		Facsimile: (314) 854-1580 	(b) If to Clark USA 		Clark USA, Inc. 		8182 Maryland Avenue 		St. Louis, Missouri 63105-3721 		Attn: Maura Clark 		Facsimile: (314) 854-1580 	(c) if to Assignee: 		J. Aron & Company 		85 Broad Street 		New York, New York 10004 		Attn: W. Thaddeus Miller 		Facsimile: 212-902-3876 	(d) if to OPC: 		Occidental Petroleum Corporation 		10889 Wilshire Blvd. 		Los Angeles, California 90024 		Attn: Treasurer 		Facsimile: (310) 443-6661 	(e) if to OCS: 		Occidental Crude Sales, Inc. (International) 		1200 Discovery Drive 		Bakersfield, California 93309-7008 		Attn: Lynn T. Boulware, 		Director of Financial Services 		Facsimile: (805) 321-6829 6 	(f) if to OCP: 		OXY USA, Inc. 		1200 Discovery Drive 		Bakersfield, California 93309-7008 		Attn: Lynn T. Boulware, 		Director of Financial Services 		Facsimile: (805) 321-6829 	SECTION 4.03. Headings. The descriptive headings contained in this 	Agreement are for convenience of reference only and shall not affect 	in any way the meaning or interpretation of this Agreement. 	SECTION 4.04. Severability. If any term or other provision of this 	Agreement is invalid, illegal or incapable of being enforced by any 	law or public policy, all other terms and provisions of this Agreement 	shall nevertheless remain in full force and effect so long as the 	economic or legal substance of the transactions contemplated hereby is 	not affected in any manner materially adverse to any party. Upon such 	determination that any term or other provision is invalid, illegal or 	incapable of being enforced, the parties hereto shall negotiate in good 	faith to modify this Agreement so as to effect the original intent of 	the parties as closely as possible in an acceptable manner in order 	that the transactions contemplated hereby are consummated as originally 	contemplated to the greatest extent possible. 	SECTION 4.05. Entire Agreement. This Agreement constitutes the entire 	agreement of the parties hereto with respect to the subject matter 	hereof and supersedes all prior agreements and undertakings, both 	written and oral, between the parties with respect to the subject 	matter hereof. 	SECTION 4.06. Assignment; Parties in Interest. No party to this 	Agreement (or any assignee of a party to this Agreement or any assignee 	of such assignee) shall have the right to assign its rights and 	obligations under this Agreement without the prior written consent of 	each other party (which consent shall not be unreasonably withheld); 	provided, however, that, without any consent of any other party to this 	Agreement being necessary, (i) Assignee may assign all or any portion 	of its rights and obligations under this Agreement to The Goldman Sachs 	Group, L.P. (including any successor entity, "Group") or any company a 	majority of the voting interests in which are owned or controlled by 	Group and (ii) in connection with any securitization of this Agreement 	(the "Securitization") Assignee and any Securitization vehicle shall 	have the right to assign or otherwise transfer all or any portion of 	its rights and obligations under this Agreement to any Securitization 	vehicle that assumes such obligations. This Agreement shall be binding 	upon and inure solely to the benefit of the parties hereto (and any 	Securitization vehicle or other proper assignee of the Assignee or any 	Securitization vehicle in accordance with this Section 4.06), and 	nothing in this Agreement, express or implied, is intended to or shall 	confer upon any other person any right, benefit or remedy of any nature 	whatsoever under or by reason of this Agreement provided that the 	provisions of Section 1.01(b) and Section 3.03 shall also be for the 	benefit of the other parties to the Instruments. Each party to this 	 7 	Agreement acknowledges and agrees that the provisions of this Section 	4.06 pertain only to assignments of the rights and obligations of the 	parties under this Agreement and do not pertain, and have no effect on, 	the right of the Assignee to assign or otherwise dispose of the 	Instruments (it being understood that the right of the Assignee or any 	successor to assign or otherwise dispose of the Instruments or any of 	its rights or obligations thereunder shall be governed solely by the 	terms of the Instruments). 	SECTION 4.07. Governing Law. This Agreement shall be governed by, and 	construed in accordance with, the laws of the State of New York. With 	respect to any suit, action or proceedings relating to this Agreement, 	each party irrevocably submits to the non-exclusive jurisdiction of the 	courts of the State of New York and federal courts located in the 	Borough of Manhattan in New York City and of the courts of the State of 	Missouri and federal courts located in St. Louis. 	SECTION 4.08. Contract Crude Oil. OCP acknowledges that (i) the 	provisions of Section 2.04 of the Purchase Contract (as defined in 	Annex A) shall be of no force or effect, and (ii) it has no, and waives 	any, right pursuant to Section 2.04 of the Purchase Contract to reduce 	the number of Barrels of Contract Crude Oil (both as defined in such 	Purchase Contract) it is obligated to deliver. 	SECTION 4.09. Indemnification. Each of the Assignor and the Assignee 	agrees to indemnify the other from and hold it harmless against any and 	all losses, damages, liabilities, claims and costs (including attorneys 	fees) which the indemnified party may sustain by reason of any breach by 	the indemnifying party of any of the representations, warranties and 	agreements by the indemnifying party contained in this Agreement. Each 	of the Assignor and the Assignee acknowledges that its obligations under 	this Section 4.09 shall survive any assignment of its rights and 	obligations under this Agreement made in accordance with Section 4.06. 	SECTION 4.10. Further Assurances. Each of Assignor, Clark USA, OPC, 	OCS and OCP agrees to execute and deliver such additional documents, and 	take such additional steps, as either Assignee or any proper transferee 	from Assignee in accordance with Section 4.06 (including a 	Securitization vehicle) may reasonably request in order to more fully 	give effect to the 8 	 	sale, assignment, transfer and assumption provided 	for in Article I and to assist in the consummation of the 	Securitization, provided, however, that neither OPC, OCS or OCP shall 	be required to execute and deliver any document or take any action if 	the result thereof is to (i) cause such party to incur any expense which 	is not reimbursed to it by Assignee or a proper transferee of Assignee 	in accordance with Section 4.06 or (ii) subject OPC, OCS or OCP to 	liability. Each of OCP, OCS and OPC also acknowledges that Assignee 	is planning a Securitization and will make a standard non-petition 	covenant with respect to any bankruptcy remote Securitization vehicle 	upon the request of one or more rating agencies. 	SECTION 4.11. Interpretations. (a) It is Assignor's and Clark USA's 	understanding that for purposes of Section 1 of the L/C Agreement (as 	defined in Annex A), if an amount is drawn under the L/C (as defined in 	Annex A), and it is determined (through arbitration, by agreement of the 	parties or otherwise) that a portion of such draw was made for a purpose 	permitted under the L/C Agreement (the "Permitted Amount") and that the 	balance of such draw was not made for a purpose permitted under the L/C 	Agreement (the "Impermissible Amount") , OPC (i) shall be required in 	accordance with the terms of the L/C Agreement to cause the amount 	available to be drawn under the L/C to be increased by an amount equal 	to the Permitted Amount and (ii) shall be entitled to receive a refund 	of an amount equal to the Impermissible Amount from the person that 	drew it. 	(b) It is Assignor's and Clark USA's understanding that all 	references to "WTI (at Cushing, Oklahoma), as published in Platt's" in 	the definition of "WTI Reference Price" in any of the Instruments refers 	to the WTI price on line 1 in Platt's Oilgram Price Report. 	SECTION 4.12. Miscellaneous. (a) Each of OCS and OCP shall deliver to 	Assignee (with a copy to Assignor) (in each case in accordance with 	Section 4.02) information (including, without limitation, monthly 	statements) of the type and content that have been furnished to Clark 	USA in connection with any of the Instruments on a similar schedule. 	(b) Assignor agrees to instruct OCS and OCP (i) to make all payments 	that OCS is obligated to make pursuant to the Marketing Contract 	(as defined in Annex A) in respect of Delivery Dates (as defined in the 	Marketing Contract) on 	 9 	or after September 1, 1996 to Assignee and (ii) to replace Assignor with 	Assignee in all oil contracts entered into pursuant to the Purchase 	Contract and the Marketing Contract (both as defined in Annex A) after 	the Effective Date. 	SECTION 4.13. Use of Proceeds Assignor agrees to use and apply all 	amounts received pursuant to Section 1.02 hereof in accordance with the 	terms of each agreement binding on or affecting Assignor or Clark USA 	or any of their respective assets, including, without limitation, the 	following: (i) the Indenture dated as of September 15, 1992, as amended, 	between Assignor and Nationsbank of Virginia, N.A., as Trustee, 	relating to $175,000,000 9-1/2% Senior Notes due September 15, 2004; 	(ii) the Indenture dated as of December 1, 1991, between Assignor and 	Sovran Bank, NA., as Trustee, relating to $225,000,000 10-1/2% Senior 	Notes due December 1, 2001; (iii) the Indenture dated as of May 15, 	1993, as amended, between Clark USA and Bankers Trust Company, as 	Trustee, relating to $264,000,000 Senior Secured Zero Coupon Notes due 	2000; and (iv) the Indenture dated as of December 1, 1995, between 	Clark USA and The Chase Manhattan Bank, N.A., as Trustee, relating to 	$175,000,000 Senior Notes due 2005. 10 		 	IN WITNESS WHEREOF, the parties have caused this Agreement to be 	executed as of the date first written above by their respective officers 	thereunto duly authorized. 					CLARK REFINING & MARKETING, INC. 					By: /s/ M. J. Clark 		 					Name: Maura J. Clark 					Title: Executive Vice President 					& Chief Financial Officer 					CLARK USA, INC. 					By: /s/ M. J. Clark 					Name: Maura J. Clark 					Title: Executive Vice President 					& Chief Financial Officer 					J. ARON & COMPANY 					By: /s/ Steven M. Schultz 					Name: Steven M. Schultz 					Title: Partner 11 As of the date first written above, the undersigned hereby consent to the terms hereof, and on their own behalf acknowledge and agree to the provisions of Sections 4.06, 4.08, 4.10 and 4.12(a). 					OCCIDENTAL PETROLEUM CORPORATION 					By: /s/ John W. Alden 					Name: John W. Alden 					Title: Assistant Secretary and 						Assistant Treasurer 					OCCIDENTAL C.O.B. PARTNERS 					By OXY USA, Inc., its Managing Partner 					By: /s/ John W. Alden 					Name: John W. Alden 					Title: Assistant Secretary 					OCCIDENTAL CRUDE SALES, INC. 					(INTERNATIONAL) 					By: /s/ Linda S. Peterson 					Name: Linda S. Peterson 					Title: Vice President and Secretary 12 Annex A 1. Crude Oil Purchase Contract (the "Purchase Contract"), dated as of December 1, 1995, between Occidental C.O.B. Partners and Clark U.S.A., Inc. 2. Crude Oil Marketing Contract (the "Marketing Contract"), dated as of December 1, 1995, between Clark U.S.A., Inc. and Occidental Crude Sales, Inc. (International) ("OCS"). 3. Guaranty, dated as of December 1, 1995 (the "Guaranty"), from Occidental Petroleum Corporation in favor of Clark U.S.A., Inc. of the obligations of OCP and OCS under the Purchase Contract and the Marketing Contract, respectively. 4. Letter of Credit Agreement (the "L/C Agreement"), dated as of December 1, 1995, between Clark U.S.A., Inc. and Occidental Petroleum Corporation. 5. Designation Agreement, dated as of December 1, 1995, between Clark USA, Inc. and Occidental C.O.B. Partners. 6. Irrevocable Letter of Credit No. LASB-226690 dated (the "L/C") November 28, 1995, as amended, issued by the Bank of America National Trust and Savings Association in favor of Clark USA, Inc.