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Azodicarbonamide

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Azodicarbonamide

Azodicarbonamide
Skeletal formula of azodicarbonamide
Space-filling model of azodicarbonamide
Names
IUPAC name
Carbamoyliminourea
Other names
Azodicarboxamide; Azobisformamide; C,C'-Azodi(formamide); Diazenedicarboxamide
Identifiers
 Y
ChEMBL  Y
ChemSpider  Y
EC number 204-650-8
Jmol-3D images Image
PubChem
UNII  Y
Properties
C2H4N4O2
Molar mass 116.08 g·mol−1
Appearance Yellow to orange/red crystalline powder
Melting point 225 °C (437 °F; 498 K) (decomposes)
Hazards
Safety data sheet [2]
Harmful (XN)
R-phrases R42 R44
S-phrases S22 S24 S37
NFPA 704
1
1
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 Y  (: Y/N?)

Azodicarbonamide, or azo(bis)formamide, is a chemical compound with the molecular formula C2H4O2N4.[1] It is a yellow to orange red, odorless, crystalline powder. As a food additive, it is known by the E number E927.

Contents

  • Uses 1
    • As a blowing agent 1.1
      • Safety and regulation 1.1.1
    • As a food additive 1.2
      • Safety and regulation 1.2.1
  • References 2
  • External links 3

Uses

As a blowing agent

The principal use of azodicarbonamide is in the production of foamed plastics as a blowing agent. The thermal decomposition of azodicarbonamide results in the evolution of nitrogen, carbon monoxide, carbon dioxide, and ammonia gases, which are trapped in the polymer as bubbles to form a foamed article.

Azodicarbonamide is used in plastics, synthetic leather, and other industries and can be pure or modified. Modification affects the reaction temperatures. Pure azodicarbonamide generally reacts around 200 °C. In the plastic, leather, and other industries, modified azodicarbonamide (average decomposition temperature 170 °C) contains additives that accelerate the reaction or react at lower temperatures.

An example of the use of azodicarbonamide as a blowing agent is found in the manufacture of vinyl (PVC) foam, where it plays a role in the formation of air bubbles by breaking down into gas at high temperature. Vinyl foam is springy and does not slip on smooth surfaces. It is useful for carpet underlay and floor mats. Commercial yoga mats made of vinyl foam have been available since the 1980s; the first mats were cut from carpet underlay.[2]

Safety and regulation

Azodicarbonamide as a blowing agent in plastics has been banned in the European Union since August 2005 for the manufacture of plastic articles that are intended to come into direct contact with food.[3]

In the [5] The WHO concluded, "The level of risk is uncertain; hence, exposure levels should be reduced as much as possible."

As a food additive

As a food additive, azodicarbonamide is used as a flour bleaching agent and a dough conditioner.[6] It reacts with moist flour as an oxidizing agent.[7] The main reaction product is biurea, a derivative of urea, which is stable during baking.[7] Secondary reaction products include semicarbazide and ethyl carbamate.[6]

Safety and regulation

In the United States, azodicarbonamide has generally recognized as safe (GRAS) status and is allowed to be added to flour at levels up to 45 ppm.[8][9] Azodicarbonamide has not been authorized for use in Australia and the European Union as a food additive.[9][10]

In 2014, amid public discomfort with the dual uses of azodicarbonamide, the sandwich franchise Subway announced that it would no longer use it as a dough conditioner.[11]

References

  1. ^ "Azodicarbonamide (CICADS)". Inchem. World Health Organization, Geneva, 1999.
  2. ^  
  3. ^ "COMMISSION DIRECTIVE 2004/1/EC of 6 January 2004 amending Directive 2002/72/EC as regards the suspension of the use of azodicarbonamide as blowing agent".  
  4. ^ "Substances causing/worsening asthma". UK Occupational Health and Safety.  
  5. ^ "Concise International Chemical Assessment Document 16: Azodicarbonamide" (PDF).  
  6. ^ a b FDA Frequently Asked Questions on Azodicarbonamide (ADA) Page Last Updated: 20 June, 2014
  7. ^ a b WHO FAO 1965. Toxicological Evaluation of Some Antimicrobials, Antioxidants, Emulsifiers, Stabilizers, Flour-Treatment Agents, Acids and Bases: Azodicarbonamide FAO Nutrition Meetings Report Series No. 40A,B,C. WHO/Food Add./67.29
  8. ^ "21CFR172.806".  
  9. ^ a b Smith, Jim; Hong-Shum, Lily (2011). Food additives data book (2nd ed.). Chichester, West Sussex: Wiley-Blackwell. p. 548.  
  10. ^  
  11. ^ Elizabeth Landau (17 February 2014). "Subway to remove 'dough conditioner' chemical from bread". CNN. Retrieved 23 January 2015. 

External links

  • International Chemical Safety Card
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