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# c12) United States Patent 

# Schraven et al. 

# (54) METHOD FOR PRODUCING A FREE ACID FROM THE SALT THEREOF 

(75) Inventors: Alexander Schraven, Issum (DE); Thomas Tacke, Alzenau (DE); Thomas Haas, Muenster (DE); Christoph Kobler, Alzenau (DE); Dieter Buss, Aschaffenburg (DE); Axel Ronneburg, Erlensee (DE); Olivier Zehnacker, Recklinghausen (DE) 

(73) Assignee: Evonik Degussa GmbH, Essen (DE) 

( *) Notice: Subject to any disclaimer, the term ofthis patent is extended or adjusted under 35 U.S.C. 154(b) by 506 days. 

(21) Appl. No.: 13/141,456 

(22) PCT Filed: Feb.1,2010 

(86) PCT No.: PCT /EP2010/051170 § 371 (c)(l), (2), ( 4) Date: Jun.22,2011 

(87) PCT Pub. No.: WO2010/094554 

PCT Pub. Date: Aug. 26, 2010 

## (65) Prior Publication Data 

US 2011/0257429 Al Oct. 20, 2011 

## (30) Foreign Application Priority Data 

Feb. 19, 2009 (DE) ......................... 10 2009 009 580 

(51) Int. Cl. C07F 9122 (2006.01) 

(52) U.S. Cl. USPC .............................................................. 562/8 

( 58) Field of Classification Search None See application file for complete search history. 

## (56) References Cited 

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## U.S. PATENT DOCUMENTS 

<img src='content_image/922610.jpg'>

# (IO) Patent No.: US 8,809,576 B2 

# (45) Date of Patent: Aug. 19, 2014 

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## FOREIGN PATENT DOCUMENTS 

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McMaster et al., The Neutral Ammonium Salts of Organic Acids and their substituted Derivatives, J. Amer. Chem. Soc., 1918, 40(4), 683- 693.* 

International Search Report issued Apr. 12, 2010 in PCT/EPl0/ 51170 filed Feb. 1, 2010. 

U.S. Appl. No. 13/001,204, filed Dec. 23, 2010, Reinecke, et al. 

U.S. Appl. No. 13/002,519, filed Jan. 4, 2011, Haas, et al. 

U.S. Appl. No. 61/239,634, filed Sep. 9, 2009, Kobler, et al. 

U.S. Appl. No. 14/126,607, filed Dec. 16, 2013, Hass, et al. 

U.S. Appl. No. 14/233,505, filed Jan. 17, 2014, Poetter, et al. 

U.S. Appl. No. 14/237,121, filed Feb. 4, 2014, Haas, et al. 

U.S. Appl. No. 14/238,576, filed Feb. 12, 2014, Schaffer, et al. 

U.S. Appl. No. 14/238,591, filed Feb. 12, 2014, Schaffer, et al. 

* cited by examiner 

Primary Examiner - Porfirio Nazario Gonzalez 

Assistant Examiner - Kofi Adzamli 

(74) Attorney, Agent, or Firm -Obion, Spivak, McClelland, Maier & Neustadt, L.L.P. 

## (57) ABSTRACT 

The invention relates to an improved method for releasing an organic acid, preferably a carbon, sulfone or phosphone acid, particularly an alpha or beta hydroxycarbon acid, from the ammonia salt thereof by releasing and removing ammoniac and simultaneous extraction of the released acid, having an amine as a suitable extraction means from the aqueous phase. This method corresponds to a reactive extraction. The reac› tive extraction of an organic acid from the aqueous ammonia salt solution thereof can be significantly improved by the use of a strip medium or carrier gas, such as nitrogen, air, water vapor or inert gases such as argon. The released ammoniac is removed from the aqueous solution by the continuous gas flow and can be resupplied into a production process. The free acid can be obtained by a method such as distillation, rectifi› cation, crystallization, reextraction, chromatography, adsorp› tion or by a membrane method from the extraction means. 

US008809576B2 

## OTHER PUBLICATIONS 

## 12 Claims, 3 Drawing Sheets 

