Questions about Urea.

MJLMJL Member
edited April 1 in Formulating
Hi, 

I have a few questions about Urea. 

1) Is it hard to “stabilize”?
- Does it degrade or precipitate? Under what conditions?
- Does it always change the pH of a product? Are there ingredients to add to prevent pH shifts? 

2) Is there any difference at all between the various forms of Urea: Hydroxyethl, Imidazolidinyl, Diazolidinyl, and Urea USP? 
- Is one form more stable/easier to work with than others?
- Do ALL forms of Urea release formaldehyde?

Thanks for your time. 

Comments

  • em88em88 Member
    1) Is it hard to “stabilize”?
    Yes
    - Does it degrade or precipitate? Under what conditions?
    It degrades. Water and temperature presence are enough.
    - Does it always change the pH of a product? Are there ingredients to add to prevent pH shifts? 
    Yes. You need to add a buffer system

    2) Is there any difference at all between the various forms of Urea: Hydroxyethl, Imidazolidinyl, Diazolidinyl, and Urea USP? 
    Not every compound with "urea" in the name is urea! Check the molecule to understand. 
    - Is one form more stable/easier to work with than others?
    Urea is only one. 
    Structural formula of urea
    - Do ALL forms of Urea release formaldehyde?
    Probably 


  • AzizAziz Member
    @em88 thanks for your valuable information . 
  • Bill_TogeBill_Toge Member, Professional Chemist
    em88 said:
    - Does it degrade or precipitate? Under what conditions?
    It degrades. Water and temperature presence are enough.

    that's a new one on me - amides like urea are usually stable unless you have a lot of alkali present
    just out of interest, what does it degrade to?

    - Do ALL forms of Urea release formaldehyde?
    Probably

    only urea/formaldehyde condensates, e.g. imidazolyl urea, do this
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • em88em88 Member
    edited April 3
    Bill_Toge said:
    that's a new one on me - amides like urea are usually stable unless you have a lot of alkali present

    There are many articles that mention a degradation of urea in NH3 and CO2.
    I've noticed myself an increasement of pH over time. 
    In creams is even easier to spot the bubbles of CO2. 
    https://www.ncbi.nlm.nih.gov/pubmed/25043489
     
    Indeed, taking in consideration that there are covalent bonds, urea should be stable, but in my experience urea was not stable.

    Bill_Toge said:
    only urea/formaldehyde condensates, e.g. imidazolyl urea, do this
    My mistake, was thinking about something else.  :) 
  • MJLMJL Member
    Thank you, @Bill_Toge
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