Please note that this compound didn't keep well, so there is not too much sense to get a large stack unless you got a really large consumption. And in small quantities it is wide available, for example, from artcraft:
http://www.artcraftchemicals.com/products/products-page/general-chemistry/a-m/cd-4-part-1095/
Well - thats indeed the problem with liquid chems in general.
Tetenal for example
don't give expired dates to their liquids.
There is allways a note : " Use within 2 years " onto the packaging.
Imagine some developers may stand to min. 1 year in the store / at your lokal dealer - so it should last more than 2 years before the chems are unusable.
I personaly give them a minimum of 3 -5 years. With great luck 6 or may be 7 years.
But it is relative 1) of cause only in original unopened bottles.
2) brand new avaible at your local dealer.
But now I am a little bit confused because I now CD 4 also as raw chemical
4 - (N- Ethyl-N-2-hydroxyethyl) - 2 methylphenylendiamine sulfate.

...
(terrible name) by the time "phenylendiamine" indicates you should use this chemical with respect because it may cause alergic reactions.
And more - we better will not talk about

!
Perhaps I mixed some issues from bad remind - but CD4 (Cas 25646 - 77 - 9) is also avaible as crystalline powder (white - sometimes beige colored).
And in this form it may last longer - may be I mixed something (as I sayd).
As we should know it react with oxygen
(glad it has this reaktive potential

)
So this white powder darkens upon exposure to air.
By the time - 1,4 - Phenylendiamine we better know as ppd, darkens so much in a simular reaction so we can't say ppd powder is white.
(after a relative short time it becomes a dark-brownish color)
So from my understanding this chemicals should be stored in a "nearly vacoum" plastic packaging.
But this should stable the cristals from chemical reactions ?
Obviously the structure of CD4 is more extensive than simple ppd - so as PE mentioned: " It does not keep well "
( and this in sealed bottles with a Nitrogen blanket in top) ...!

...
But why is this so ?
I also remember a couple of years Tetenal c41 kits as "powder developer"
as I know these kits have been the last powder kits avaible at all.
And many stated :" they last for ever ".
Well - such statements to powder chems are nonsence.
But a full decade should be realistic like it is with many bw powder kits.
(ILFORD perceptol, Kodak D76 ...a.s.o)
Any ideas what the reason is I am wrong?
Obviously I made a mistake from understanding of inactive reactions of powder developers?
with regards