Gibberellenic acid

Structure (XII) with the attachment of the lactone bridge reversed can be ruled out for the following reason. Gibberellic acid decomposes slowly in aqueous solution to give gibberellenic acid first described by Gerzon, Bird, and Woolf (16) who suggested the homoannular diene structure (XV). We consider that the ultraviolet absorption (Amax 253 m/ e 22,400) is more in accord with the hetero-annular structure (XIV) and this is confirmed (25) by ultraviolet absorption (Amax 309 mfi e 16,500) of the derived dienone (XVII) which is decisive [cf. the ultraviolet absorption (Araax 310 m/ e 3900) of model cyclohexadienone (XVIII)]. 

I, GIBBERELLIC ACID II, HYDROLYSIS PRODUCT III. GIBBEREllENIC ACID... 

A rapid quantitative method for the determination of gibberellic acid is based on the conversion of gibberellic acid to gibberellenic acid, followed by measurement of the absorption of the latter compound at 254 ny. The method has been shown to be specific for gibberellic acid and tolerant of the presence of other known impurities and decomposition products. It has been successfully applied to a wide range of fermentation samples. 

The rate of decomposition of gibberellenic acid has been measured under the conditions employed for gibberellic acid determination. The graph relating fall in absorbance with time is reproduced in Figure 3. 

Where gibberellenic acid is present in significant amount, either alone or accompanied by Sumikfs acid, the following procedure has been found satisfactory for the correction of blank reading to compensate the interference introduced as a result of the presence of the former compound. 

Then Corrected blank = observed blank — (gibberellenic acid content X... 

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