Download Semiconductor electronics class 12th physics notes.
Tuesday, February 19, 2013
Tuesday, February 12, 2013
Monday, February 11, 2013
group detection pratical
Here is a good article i found online
and it also turns lime water milky. Your job is complete and -COOH is detected.
anywhere but the reagent in the rkn and the colour should be remembered.
BUT MORE IMPORTANT IS DISTINCTION BETWEEN 1, 2 and 3 degree alcohols....
Many tests are present but more important and easy to remenber are....
giving orange/red/yellow colour crystalline products with DNP . (see the rkn)
BUT the questions arises HOW to distinguish b/w Aldehydes and Ketones ? Well here's the answer...
Here is aldehydes VS, Ketones:
The most important fact about tollens and fehlings test is that even though ketone is not rediced by these
two soln.
alpha hydroxy ketones
ARE.. and this is very important factor as this is the reason
monosacchirides reduce tollens reagent...
1) CH3CH2OH 2) 2 degree alcohol but should be adjacent to terminal carbon
{ PLEASE NOTE THAT ALKYL HALIDES HAVING SAME STRUCTURE as above two give +ve iodoform test
as in alkaline medium as OH replaces Cl.}
3)Every compound containing CH3CO ( acetyl group ) attached to H or C gives this test therefore among
aldehydes only CH3CHO gives this test...
THE end product is iodoform which is liberated when compounds containing any of the above groups
is passed through I2 an KOH...The colour liberated is yellow...
reacts with FeCl3 to form a complex giving purple or deep red colour(see the rkn)
2)Hydrolysis Test : Now this one is common usually called saponification.You all may already know the rkn.
The rub is that alongwith NaOH Phenolphthalin is added to ester which gives pink colour but when the soln
is boiled pink colour is discharged due to formation of acid...
NaNO2 + dil. HCl are added to the amines..
----Primary aliphatic amines liberate N2 gas with brisk effrvesence and clear soln is formed(see rkn)
----Primary aromatic amines give stable diazonium salt..and this benzene diazonium chloride gives
orange azo dye with alkaline beta naphthol( must have read the rkn in amines)
----R2NH (Secondary amine) gives oily yellow liquid...(see the rkn)
2)Baeyer's test : Alkene and Alkynes also decolourise alk. KMnO4 ( Baeyer's Reagent)
Now how to distinguish BETWEEN Alkynes and Alkenes:
alkenes decolorise bromine water very rapidly, but alkynes take several minutes.
Finally its over, and i hope i have covered every compound..I hope you will find this article helpful..
If any result of rkn is wrongly written plz point it out ASAP and if there is any grammatical error plz .....
dont bother me or yourself
Last but not the least thanks for reading my article coz i have put a lot of hardwork in it...
for class 12 th organic chemistry chemistry group detection pratical
I start off with CARBOXYLIC GROUP ( -COOH )
The best method for the detection is NaHCO3 test. Carboxylic acids liberate CO2 with BRISK EFFERVESENCEand it also turns lime water milky. Your job is complete and -COOH is detected.
Alcoholic Group (-OH)
Alcohols give red colour when CAN (ceric ammonium nitrate) is added to it. You can see the actual rknanywhere but the reagent in the rkn and the colour should be remembered.
BUT MORE IMPORTANT IS DISTINCTION BETWEEN 1, 2 and 3 degree alcohols....
Many tests are present but more important and easy to remenber are....
1) Lucas test (When alcohol is passed through( ZnCl2+ HCl) : 3 degree gives
white turbidity immediatly,
2 degree gives tirbidity after 1 or 2 mins , 1 degree does not give any rkn at room temp
2) Victor Meyer test: Now this is carried in various stages and based on the colour of
the end product, distinction can be made: 1 degree gives red colour, 2 degree gives
blue while 3 degree gives colourlees soln.I repeat that more than the rkn the
end colour is more imp.
Phenolic Group (-OH attached to benzene nucleus)
Phenolic group give characteristic colour with neutral FeCl3 soln.(see the actual rkn)Carbonyl groups(Aldehydes + Ketones):
1) Brady's test (commonly known as 2,4 DNP test) : This test is given by both Aldehydes and ketones bygiving orange/red/yellow colour crystalline products with DNP . (see the rkn)
BUT the questions arises HOW to distinguish b/w Aldehydes and Ketones ? Well here's the answer...
Here is aldehydes VS, Ketones:
The most important fact about tollens and fehlings test is that even though ketone is not rediced by these
two soln.
alpha hydroxy ketones
ARE.. and this is very important factor as this is the reason
monosacchirides reduce tollens reagent...
2)Iodoform test : This is very important test as it covers everyone from alcohols to
aldehydes and ketones....
Actually only the following groups give this test and it is better to memorise them..1) CH3CH2OH 2) 2 degree alcohol but should be adjacent to terminal carbon
{ PLEASE NOTE THAT ALKYL HALIDES HAVING SAME STRUCTURE as above two give +ve iodoform test
as in alkaline medium as OH replaces Cl.}
3)Every compound containing CH3CO ( acetyl group ) attached to H or C gives this test therefore among
aldehydes only CH3CHO gives this test...
THE end product is iodoform which is liberated when compounds containing any of the above groups
is passed through I2 an KOH...The colour liberated is yellow...
Ester Group(RCOOR') :
1) Hydroxamic Test : Esters react with NH2OH(hydroxul amine) to give Hydroxamic acid which thenreacts with FeCl3 to form a complex giving purple or deep red colour(see the rkn)
2)Hydrolysis Test : Now this one is common usually called saponification.You all may already know the rkn.
The rub is that alongwith NaOH Phenolphthalin is added to ester which gives pink colour but when the soln
is boiled pink colour is discharged due to formation of acid...
Amide Group(-CONH2 ) :
Amides are simply decomposed by alkali soln liberating NH3 gas which give WHITE FUMES with HClAmines(RNH2, R2NH, R3N , ArNH2)
NITROUS ACID TEST :NaNO2 + dil. HCl are added to the amines..
----Primary aliphatic amines liberate N2 gas with brisk effrvesence and clear soln is formed(see rkn)
----Primary aromatic amines give stable diazonium salt..and this benzene diazonium chloride gives
orange azo dye with alkaline beta naphthol( must have read the rkn in amines)
----R2NH (Secondary amine) gives oily yellow liquid...(see the rkn)
Unsaturation Test ( for alkene and alkynes) :
1) Bromine water test: Both of them decolourise Br2 water..2)Baeyer's test : Alkene and Alkynes also decolourise alk. KMnO4 ( Baeyer's Reagent)
Now how to distinguish BETWEEN Alkynes and Alkenes:
alkenes decolorise bromine water very rapidly, but alkynes take several minutes.
Finally its over, and i hope i have covered every compound..I hope you will find this article helpful..
If any result of rkn is wrongly written plz point it out ASAP and if there is any grammatical error plz .....
dont bother me or yourself
Last but not the least thanks for reading my article coz i have put a lot of hardwork in it...
Saturday, February 9, 2013
Organic name reactions
Do you find remembering organic reactions difficult ??
If yes then Use this chart/table to learn organic reactions easily.
Usedul for both entrance exam and cbse board exam
Organic reactions ,reagents,conditions and products.
If yes then Use this chart/table to learn organic reactions easily.
Usedul for both entrance exam and cbse board exam
Organic reactions ,reagents,conditions and products.
Friday, February 1, 2013
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