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  1. #11

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    Quote Originally Posted by Photo Engineer View Post
    I would not work with it either and I doubt if anyone would in a small darkroom, and therefore there will never be any real way to prove whether it is or is not.
    PE
    Ron, I once synthesised pyridylhydroquinone from quinone and pyridine as mentioned in Glafkides. IIRC, it is a fine grain developing agent similar in action to chlorhydroquinone. The compound consisted of fine yellow needles. When used in a developer the solution turned dark red when the alkali was added. The one drawback was that it slowly decomposed in solution to produce pyridine which has a VERY bad smell. For those who are unfamiliar with this chemical, once you get a whiff of pyridine it seems to stay in your nose for quite some time. Ethyl ether has the same effect. No one would want that smell in their darkroom.

    Just a caution -- do not attempt anything like this at home. Quinone is a highly reactive and very nasty chemical. The LD50 dose is 25 mg/kg for mice.
    Last edited by Gerald C Koch; 03-30-2012 at 06:14 PM. Click to view previous post history.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

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  2. #12
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    Quote Originally Posted by Gerald C Koch View Post
    If you look at the rule it says that the chain linking the two developer groups must begin and end with a double bond.
    That clears it up quite a bit. Since vinyl alcohol changes its structure to acetaldehyde as soon as it gets a chance to, I naively assume that this would make the linear structure -C=C-OH highly unstable in general, while OH attached to a benzene ring is stable hence has a chance to work as dev before bad things happen to it. There is no reason to risk blow up our little dark rooms with alkadiene-diols after all.

    It may all be obvious to real chemists, but for extra clarity we could rephrase the A-(C=C)n-A' rule as A-C=C-whatever-C=C-A', maybe with the hint that the C=C double bonds may(and in all likeliyhood will) come from an aromatic ring.
    Trying to be the best of whatever I am, even if what I am is no good.

  3. #13

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    The double bonds do not have to be in an aromatic ring. The rule also fits aliphatic compounds such as the butadiene compound mentioned above. Remember cases like hydrazine and hydroxyamine where n = 0.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  4. #14
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    Jerry;

    Pyridine is also detrimental to having children. It causes loss in fertility and mutations.

    In any event, I am just pointing out that there are a lot of potential developers out there, and a lot of them do not fit a general rule. The more accurate rules are based on redox potential vs AgX and the ability to discriminate between unexposed silver halides and exposed silver halides.

    PE

  5. #15

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    I love the smell of diethyl ether! One of the better smelling solvents I work with.

    Pyridine, some people really don't like it, but after using for 20 years as part of the color reagent for the cyanide test, I'm used to it.

    Ketones (other than acetone) are another one I don't like, and ethyl acetate is not so nice either.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

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