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succinic anhydride
Posted: Sat Feb 04, 2006 6:04 am
by lotussss
Hello,
I must find a method to analyse succinic anhydride or other anhydride.
What kind of mobile phase can I use ? I think 100% water with reverse phase ?
Tanks.
Posted: Sat Feb 04, 2006 3:26 pm
by SIELC_Tech
Anhydrides will hydrolize in presense of water to corresponding diacids. This will give you a very poor peak shape (decomposing on the column). what you can do is to react it with benzylamine (for UV) or ammonia.
Regards,
Vlad
Posted: Sat Feb 04, 2006 5:36 pm
by james little
We do a lot of anhydrides by GC-MS. First heat with dimethylamine to open the anhydride, then silylate with BSTFA to derivatize anhydride group. Also any succinic acid will be detected as its di-TMS ester.
See my site on silylation arfitfacts, it has some general silylation advice..
http://users.chartertn.net/slittle/
Posted: Sat Feb 04, 2006 6:14 pm
by SIELC_Tech
HPLC is faster way (my opinion) as you only have to react anhydride with amine. In case of benzylamine you can do RP HPLC with UV detection (210-230 nm). ACN/water/phosphoric acid will give you nice elution. Reaction of anhydride and amine is very fast and you end up with monobenzylamide of diacid. Make sure that you are using dry reagents to avoid succinic acid formation (hydrolysis).
Regards,
Vlad
Posted: Sun Feb 05, 2006 5:01 am
by lotussss
Thank you for your answers,
But if I do make react an amine (dry reagent), I risk to form impurities of reaction?
Thank you.
Posted: Sun Feb 05, 2006 3:27 pm
by james little
All reactions have impurities. If you use a primary amine for the reaction, could form an imide for the ring closure of the initial amide/acid reaction of succinic acid with the primary amine. Thus might be better to use a secondary amine.
Don'd know how critical to have very dry reagent. The amine will probably react faster than water with succinic anhydride.
Think I would would be sure the reagent is free of any other amine impurities..
Posted: Mon Feb 06, 2006 1:57 am
by Bill Tindall
It is commonly thought that anhydrides are rapidly hydrolyzed in water, but unless a base is present this rate can be very slow. For example the hydorlysis rate of acetic anhydride is very slow at acidic pH. Many aliphatic anhydrides can be successfully analyzed by reversed phase chromatography- see JChrom. 868 (2000)41-50). The anhydrides are well separated from their corresponsing acids. I don't know if succinic anhydride can be done, but it is worth a try.