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Thread: Chemistry query

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    Chemistry query

    Not really a puzzle, but I'm puzzled. I read on a cleaning product label the term "quaternary ammonium compounds". As far as I recall, "ammonium" refers to the monovalent NH(4)+ ion. Where does the "quaternary" feature in its compounds. I also recall ammonia as forming complexes, but that's not ammonium. I'll bet Steve would know <img src=/S/sneaky.gif border=0 alt=sneaky width=15 height=15>.

    Alan

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    Re: Chemistry query

    Quaternary refers to tetra-substituted.
    Ammonium does refer to the NH4+ cation and it contain many different anions [Cl- (ammonium chloride), OH- (ammonium hydoxide), etc]

    Quaternary ammonim compounds are a more "general class" of compunds referring to substituted ammonium (hydrogen being replaced by alkyl groups) of the general formula:

    R4N+ X-

    R's can be the same group or different alkyl, aryl, etc. X can be Halide, hydroxide, etc.

    Primary (1) amines = RNH2
    Secondary (2) amines = R2NH
    Tertiary (3) amine = R3NH
    Quaternary (4) amine = R4N+ X-

    The simplest one is substituting with methyl and using chloride: Tetramethylammonium chloride:
    (CH3)4N+ Cl-

    They are often used as "phase transfer catalysts" since they are organic (with the orgainic groups) but the ionic nature (+/-) also allows solubility in water allowing it to help "transfer" materials from one phase(organic) to another(water) and increase the reaction rate.

    Steve

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    Re: Chemistry query

    Thanks Steve. They should have put that explanation on the can then IMO <img src=/S/grin.gif border=0 alt=grin width=15 height=15>. I think I learned the basis of this in year 11 chemistry, with the methane -> chloromethane -> dichloromethane -> chloroform -> carbon tetrachloride series. The context of the "quaternary" threw me here though.

    Alan

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    Re: Chemistry query

    Alan

    On a similar vein. Some cleaning products have Anioic Surfactors.

    What is an Anioic Surfactor?

    Jerry
    Jerry

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    Re: Chemistry query

    I'm only familiar with the term "surfactant". Maybe "surfactor" is some proprietry term. Either way, it sounds like a way of trying to make soap sound rather more important (and probably expensive) than it really is. Because that's what they are - soaps. The stearate is the anion (negatively charged ion) in sodium stearate, common soap. But I know they get more sophistocated e.g. to enable them to lather in acidic (hard) water, rather than precipitate like condensed milk poured into water.

    Here's a more "official" definition: From SURFace ACTive AgeNT. A substance which prefers to exist at the boundary between two other substances - for example, detergents have one end highly soluble in greasy, non-polar susbtances and one end soluble in water. Sodium dodecyl sulfate is a common surfactant. See also emulsifier.

    Alan

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    Re: Chemistry query

    That's the word, Surfactant, sorry I didn't have my bottle of Flash with me where I saw it.

    Thanks

    Jerry
    Jerry

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