For the following functional groups on 21-DesoxyDexa, indicate what chemical tes
ID: 1040866 • Letter: F
Question
For the following functional groups on 21-DesoxyDexa, indicate what chemical test would identify each group or distinguish between the two groups listed.
10. (5 pts) 21-Desoxydexamethasone is a dervative of Dexamethasone (Dexa), a potent. non-specifc coxu inh bitor used to reduce infammation. Answer the following questions about 21 DesoxyDexa 21 Desorydexamethasone itne e. es indcate what chemical test would identily each group or distinguish between the two groups listed. (5 pts) Group/Position Test Cc1,2 or 4.5 Group/Position Test OHC11 Vs c.o @ C20 vs 12.4 2" C17 9C3 OH@ C11 C17Explanation / Answer
Solution:-
1) C=C - Bromine water test if there is a double bond in the compound then the bromine water gets decolorize due to the addition of bromine across the double bond.
Reaction : C=C + Br2 ----------> Br-C-C-Br
2) C17 is tertiary alcohol whereas C11 is a secondary alcohol
we can use Lucas' reagent to distinguish between them Lucas' reagent = ZnCl2 + HCl
tertiary alcohol reacts very fast with Lucas reagent and gives the corresponding halide which is confirmed by the turbidity in the solution because halides are less soluble in aqueous solution and the tests are performed in the aqueous solution whereas secondary alcohols react slower than the tertiary alcohols so in case of tertiary alcohols the turbidity is observed within five minutes but in secondary alcohol turbidity is obtained after five minutes.
also, this can be done by using potassium dichromate tertiary alcohols do not react with the potassium dichromate so the color of potassium dichromate ( orange ) will not change but secondary alcohol reacts with potassium dichromate and gives ketone so the color of potassium dichromate will disappear in secondary alcohol.
3) Ceric ammonium nitrate test or test with sodium metal
Ceric ammonium nitrate gives pink color with alcohols and on reacting with sodium alcohols produces hydrogen bubbles so brisk effervescence will be observed.
reaction: R-OH + Na = R-O- Na+ + H2
2R-OH + (NH4)2Ce(NO3)6 -------> (R-OH)2Ce(NO3)4 + 2NH4NO3
Ceric ammonium nitrate Pink colour
4) sodium bisulphate test
Aldehyde and ketones give white crystalline substance on the addition of sodium bisulfate.
reaction:- R2 C=O + NaHSO3 ------> R2 C(OH)H(SO3)-Na+
5) Iodoform test :-
It is the test for C=O(CH3) group so C20 will give this test not C3
RC=O(CH3) + I2 + NaOH ------> RCOONa + CH3I + H2O