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UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934
(Amendment No. 19 )*

Celanese AG

(Name of Issuer)

Ordinary Shares, no par value

(Title of Class of Securities)

D1497A101

(CUSIP Number)

Celanese Europe Holding GmbH & Co. KG
c/o Celanese Corporation
Attention: Curt Shaw
1601 W. LBJ Freeway
Dallas, Texas 75234
(972) 443-4000

Copy to:

William R. Dougherty, Esq.
Simpson Thacher & Bartlett LLP
425 Lexington Avenue
New York, New York 10017
(212) 455-2000

(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

December 22, 2006

(Date of Event Which Require Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. o

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.


						1		of		24

NAMES OF REPORTING PERSONS:

Celanese Europe Holding GmbH & Co. KG

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Germany

SOLE VOTING POWER:

NUMBER OF

50,365,018

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

50,365,018

WITH

SHARED DISPOSITIVE POWER:

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

50,365,018

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

100%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						2		of		24

NAMES OF REPORTING PERSONS:

BCP Acquisition GmbH & Co. KG

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Germany

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

50,365,018

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

50,365,018

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

50,365,018

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

100%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						3		of		24

NAMES OF REPORTING PERSONS:

BCP Holdings GmbH

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Germany

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

50,365,018

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

50,365,018

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

50,365,018

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

100%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						4		of		24

NAMES OF REPORTING PERSONS:

Celanese Europe Management GmbH

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Germany

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

50,365,018

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

50,365,018

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

50,365,018

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

100%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						5		of		24

NAMES OF REPORTING PERSONS:

Celanese Caylux Holdings Luxembourg S.C.A. (formerly BCP Caylux Holdings Luxembourg S.C.A.)

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Luxembourg

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

50,365,018

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

50,365,018

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

50,365,018

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

100%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						6		of		24

NAMES OF REPORTING PERSONS:

Celanese Caylux Holdings Ltd. (formerly BCP Caylux Holdings Ltd. 1)

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Cayman Islands B.W.I.

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

50,365,018

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

50,365,018

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

50,365,018

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

100%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						7		of		24

NAMES OF REPORTING PERSONS:

BCP Crystal US Holdings Corp.

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Delaware, United States

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

50,365,018

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

50,365,018

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

50,365,018

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

100%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						8		of		24

NAMES OF REPORTING PERSONS:

Celanese Holdings LLC

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Delaware, United States

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

50,365,018

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

50,365,018

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

50,365,018

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

100%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						9		of		24

NAMES OF REPORTING PERSONS:

Crystal US Holdings 3 L.L.C.

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Delaware, United States

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

50,365,018

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

50,365,018

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

50,365,018

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

100%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


CUSIP NO.		D1497A101				10		of		24

NAMES OF REPORTING PERSONS:

Celanese Corporation

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Delaware, United States

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

50,365,018

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

50,365,018

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

50,365,018

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

100%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						11		of		24

NAMES OF REPORTING PERSONS:

Blackstone Capital Partners (Cayman) Ltd. 1

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Cayman Islands B.W.I.

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

4,399,393

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

4,399,393

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

4,399,393

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

8.74%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						12		of		24

NAMES OF REPORTING PERSONS:

Blackstone Capital Partners (Cayman) Ltd. 2

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Cayman Islands B.W.I.

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

305,110

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

305,110

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

305,110

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

0.61%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						13		of		24

NAMES OF REPORTING PERSONS:

Blackstone Capital Partners (Cayman) Ltd. 3

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Cayman Islands B.W.I.

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

2,391,928

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

2,391,928

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

2,391,928

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

4.75%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						14		of		24

NAMES OF REPORTING PERSONS:

Blackstone Capital Partners (Cayman) IV L.P.

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Cayman Islands B.W.I

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

4,399,393

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

4,399,393

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

4,399,393

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

8.74%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						15		of		24

NAMES OF REPORTING PERSONS:

Blackstone Capital Partners (Cayman) IV-A L.P.

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Cayman Islands B.W.I

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

69,886

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

69,886

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

69,886

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

0.14%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						16		of		24

NAMES OF REPORTING PERSONS:

Blackstone Family Investment Partnership (Cayman) IV-A L.P.

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Cayman Islands B.W.I

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

235,224

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

235,224

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

235,224

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

0.47%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						17		of		24

NAMES OF REPORTING PERSONS:

Blackstone Chemical Coinvest Partners (Cayman) L.P.

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Cayman Islands B.W.I

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

2,391,928

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

2,391,928

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

2,391,928

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

4.75%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						18		of		24

NAMES OF REPORTING PERSONS:

Blackstone Management Associates (Cayman) IV L.P.

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Cayman Islands B.W.I

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

7,096,431

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

7,096,431

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

7,096,431

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

14.09%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						19		of		24

NAMES OF REPORTING PERSONS:

Blackstone LR Associates (Cayman) IV Ltd.

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

Cayman Islands B.W.I

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

7,096,431

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

7,096,431

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

7,096,431

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

14.09%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						20		of		24

NAMES OF REPORTING PERSONS:

Peter G. Peterson

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

United States

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

7,096,431

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

7,096,431

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

7,096,431

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

14.09%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


						21		of		24

NAMES OF REPORTING PERSONS:

Stephen A. Schwarzman

I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):

(a) o

(b) þ

SEC USE ONLY:

SOURCE OF FUNDS (SEE INSTRUCTIONS):

BK, OO

CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):

CITIZENSHIP OR PLACE OF ORGANIZATION:

United States

SOLE VOTING POWER:

NUMBER OF

SHARED VOTING POWER:

BENEFICIALLY

OWNED BY

7,096,431

EACH

SOLE DISPOSITIVE POWER:

REPORTING

PERSON

WITH

SHARED DISPOSITIVE POWER:

7,096,431

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:

7,096,431

CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):

14.09%^*

TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):


*		The calculation of the foregoing percentage is based on 50,365,018 Ordinary Shares outstanding as of January 16, 2007 (excluding Ordinary Shares held in treasury), which number was provided to the Reporting Persons by Celanese AG.

22 of 24

This Amendment No. 19 amends and supplements the statement on Schedule 13D, filed with the Securities and Exchange Commission (the “SEC”) on December 24, 2003 (as it may be amended from time to time, the “Schedule 13D”) with respect to the ordinary shares, no par value, of Celanese AG, a German stock corporation (the “Company”). Each item below amends and supplements the information disclosed under the corresponding item of the Schedule 13D. Unless otherwise indicated herein, terms used but not defined in this Amendment No. 19 shall have the same respective meanings herein as are ascribed to such terms in the Schedule 13D.

ITEM 4. PURPOSE OF TRANSACTION.

Effective December 22, 2006, the transfer of all outstanding ordinary shares with no par value of the Company, held by the remaining minority shareholders of the Company in exchange for fair cash compensation (the “Squeeze-out”), as described in the Going Private Disclosure Document dated July 6, 2005, the Supplement to the Going Private Disclosure Document dated April 14, 2006 and other related filings, became final due to the registration in the commercial register of the Squeeze-out resolution passed at the Company’s shareholder meeting on May 30, 2006, after settlement of shareholder lawsuits challenging this shareholders’ resolution. After effectiveness of the Squeeze-out, Celanese Europe Holding GmbH & Co. KG, a subsidiary of Celanese Corporation, now holds 100% of the ordinary shares of the Company (excluding Ordinary Shares held in treasury). Mellon Investor Services will provide shareholders with the required documentation and other information to submit share certificates and upon proper submission of certificates and other required documentation will pay former shareholders €66.99 per share and a pro rata gross guaranteed dividend in the amount of €1.196 per share, which is the pro rata amount corresponding to the time from October 1, 2006, to February 28, 2007, of the gross guaranteed dividend per share for the fiscal year ending September 30, 2007. Furthermore, Celanese AG shares on which the guaranteed dividend for the fiscal year ended September 30, 2006, have not yet been paid are eligible for a gross guaranteed dividend in the amount of €2.89 per share.

On February 1, 2007, a Form 15 was filed with the Commission on behalf of the Company to commence the procedure to terminate the registration of the ordinary shares, no par value, of the Company and the Company’s reporting obligations under the Securities Exchange Act of 1934.

ITEM 5. INTEREST IN SECURITIES OF THE ISSUER

The information contained on the cover pages and in Item 4 of this Schedule 13D is incorporated herein by reference.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: February 1, 2007


		BLACKSTONE LR ASSOCIATES (CAYMAN) IV LTD.

		By:		/s/ Robert L. Friedman

				Name: Robert L. Friedman
				Title: Authorized Person

		BLACKSTONE MANAGEMENT ASSOCIATES (CAYMAN) IV L.P.

		By:		Blackstone LR Associates
		(Cayman) IV Ltd., its general partner

		By:		/s/ Robert L. Friedman

				Name: Robert L. Friedman
				Title: Authorized Person

		BLACKSTONE CAPITAL PARTNERS (CAYMAN) IV L.P.

		By:		Blackstone Management Associates
		(Cayman) IV L.P., its general partner

		By:		Blackstone LR Associates (Cayman) IV Ltd., its general partner

		By:		/s/ Robert L. Friedman

				Name: Robert L. Friedman
				Title: Authorized Person

		BLACKSTONE CAPITAL PARTNERS (CAYMAN) IV-A L.P.

		By:		/s/ Robert L. Friedman

				Name: Robert L. Friedman
				Title: Authorized Person

		BLACKSTONE FAMILY INVESTMENT PARTNERSHIP (CAYMAN) IV-A L.P.

		By:		/s/ Robert L. Friedman

				Name: Robert L. Friedman
				Title: Authorized Person

		BLACKSTONE CHEMICAL COINVEST PARTNERS (CAYMAN) L.P.

		By:		/s/ Robert L. Friedman

				Name: Robert L. Friedman
				Title: Authorized Person


		BLACKSTONE CAPITAL PARTNERS (CAYMAN) LTD. 1

		By:		/s/ Robert L. Friedman

				Name: Robert L. Friedman
				Title: Authorized Person

		BLACKSTONE CAPITAL PARTNERS (CAYMAN) LTD. 2

		By:		/s/ Robert L. Friedman

				Name: Robert L. Friedman
				Title: Authorized Person

		BLACKSTONE CAPITAL PARTNERS (CAYMAN) LTD. 3

		By:		/s/ Robert L. Friedman

				Name: Robert L. Friedman
				Title: Authorized Person

		CELANESE CORPORATION

		By:		/s/ Kevin J. Rogan

				Name: Kevin J. Rogan
				Title: Assistant Secretary

		CRYSTAL US HOLDINGS 3 L.L.C.

		By:		/s/ Kevin J. Rogan

				Name: Kevin J. Rogan
				Title: Assistant Secretary

		CELANESE HOLDINGS LLC

		By:		/s/ Kevin J. Rogan

				Name: Kevin J. Rogan
				Title: Assistant Secretary

		BCP CRYSTAL US HOLDINGS CORP.

		By:		/s/ Kevin J. Rogan

				Name: Kevin J. Rogan
				Title: Assistant Secretary

		CELANESE CAYLUX HOLDINGS LUXEMBOURG S.C.A.

		By:		Celanese Caylux Holdings Ltd., its general partner

		By:		/s/ Carsten Simon

				Name: Carsten Simon
				Title: Director

		By:		/s/ Dr. Jan-Mathias Kuhr

				Name: Dr. Jan-Mathias Kuhr
				Title: Director


		CELANESE CAYLUX HOLDINGS LTD

		By:		/s/ Carsten Simon

				Name: Carsten Simon
				Title: Director

		By:		/s/ Dr. Jan-Mathias Kuhr

				Name: Dr. Jan-Mathias Kuhr
				Title: Director

		BCP HOLDINGS GMBH

		By:		/s/ Robert L. Friedman

				Name: Robert L. Friedman
				Title: Authorized Person

		BCP ACQUISITION GMBH & CO. KG

		By:		/s/ Robert L. Friedman

				Name: Robert L. Friedman
				Title: Authorized Person

		CELANESE EUROPE HOLDING GMBH & CO. KG

		By:		Celanese Europe Management GmbH

		By:		/s/ Chinh Chu

				Name: Chinh Chu
				Title: Authorized Person

		CELANESE EUROPE MANAGEMENT GMBH

		By:		/s/ Chinh Chu

				Name: Chinh Chu
				Title: Authorized Person

		PETER G. PETERSON

		By:		/s/ Peter G. Peterson


		STEPHEN A. SCHWARZMAN

		By:		/s/ Stephen A. Schwarzman

CELANESE AG SC 13D/A