ORGANIC PREPARATION SEM-II Preparation Of β-Resorcylic Acid From Resorcinol Aim:- Organic Preparation Of β-Resorcylic Acid Requirement:-Resorcinol, K 2 CO 3 , dil. HCl, NaHCO 3 , Conc. HCl, H 2 O, Reflux Condenser, Gas Inlet Tube Procedure:- Place A Solution Containing 10 gms of Resorcinol, 50 gms of NaHCO 3 & 100 ml of H 2 O in a 250 ml R.B.F fitted with a reflux condenser & gas inlet tube heat it on a water bath for about one hour then reflux vigorously over a flam on wire gauge for 30 min. passing a rapid stream of CO 2 through the soln.[about 15 to 20 min] Acidify the soln. while still hot by adding conc. HCl. Allow to cool to room temp. chill in an ice bath and collect the crude β-Resorcylic Acid by filtration. Recrystallize the product by boiling water in present of a little decolorizing carbon filter and cool in an ice salt mixture with stirring collect and dry the pure β-Resorcylic Acid Theoretical Yield=14.0gms M.P.:-216-217 o C Reaction:- OH OH COOH OH OH NaHCO 3 -Resorcylic Acid Resorcinol Calculation:- 110 gms Resorcinol gives 154 gms β-Resorcylic Acid 10 gms Resorcinol gives (?) gms β-Resorcylic Acid = = 14.0 gms β-Resorcylic Acid Theoretical Yield=14.0gms Practical Yield = _________ gms % Yield =
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Place A Solution Containing 10 gms of Resorcinol, 50 gms of NaHCO3 & 100 ml of H2O ina 250 ml R.B.F fitted with a reflux condenser & gas inlet tube heat it on a water bath forabout one hour then reflux vigorously over a flam on wire gauge for 30 min. passing arapid stream of CO2 through the soln.[about 15 to 20 min]
Acidify the soln. while still hot by adding conc. HCl. Allow to cool to room temp. chill in anice bath and collect the crude β-Resorcylic Acid by filtration.
Recrystallize the product by boiling water in present of a little decolorizing carbon filterand cool in an ice salt mixture with stirring collect and dry the pure β-Resorcylic Acid
Take 10 gms resorcinol & heat the mixture on a sand bath until it just begins to boil. Nowallow the reaction to complete itself on sand bath without further heating for half hour.
Cool the reaction mixture and dilute it with 50% HCl[about 2 to 3 T.T] keep it for sometimes & shake it well Resacetophenone slowly separate from the solution in orange needfilters it & wash water & dry it. Recrystallized it from the boiling water.
Theoretical Yield=13.8 gms
M.P.:-144-147 oC
Reaction:-
OH
OH
OH
OH
COCH3
CH3COOH
ZnCl2-H2O
Calculation:-
110 gms Resorcinol gives 152 gms Resacetophenone
10 gms Resorcinol gives (?) gms Resacetophenone
= = 13.8 gms Resacetophenone
Theoretical Yield=14.0 gms
Practical Yield = _________ gms
% Yield =
ORGANIC PREPARATION SEM-II
Preparation Of Benzimidazole From o-phenylene diamine
Take 10gms of o-phenylene diamine in 250 ml R.B.F & 6 ml of 90% Formic acid. Heat themixture on a water bath at 100 oC for 2 hours cool the flask & then add 10% NaOH soln.slowly with constant rotation of the flask until the mixture is just alkaline [check on litmuspaper] filter off the crude Benzimidazole at the pump & wash with ice cold water forrecrystallization, dissolve the crude product in about 150 ml of water boil it & add 75 gmsof decolorizing carbon & digest for 15 minutes. Filter rapidly at the pump cool the filtrateto about 10 oC filter off the Benzimidazole wash with cold water & dry at 100 oC.
Preparation Of 4-Methyl-7-Hydroxy Coumarin From Resorcinol
Aim:- Organic Preparation Of 4-Methyl-7-Hydroxy Coumarin
Requirement:- 15 ml Conc. H2SO4, 3.7 gms Resorcinol, 5 ml Ethyl Acetoacetate, NaOH &HCl
Procedure:-
15 ml Conc. H2SO4 in a wide necked 50 ml flask cool it. Externally till the temp. of the acidis about 5 oC mean while prepare a solution of Resorcinol [3.7 gms to 4.0 gms] in 4.4 ml ofEthyl acetoacetate.
Now add the solution of Resorcinol in Ethyl Acetoacetate to Conc H2SO4 slowly. So that thetemp of mixture does not rise about 10 oC continue the stirring for 30 minutes. Pour themixture into crushed ice when the solid separates. Filter of the Coumarin at the pump. .Recrystallized it from Alcohol
in a 250ml beaker take 5.0 gms of Sulphanilic acid, 1.5 gm of Anhydrous Na2CO3 & 50 mlof water and warm until a clear solution is obtained cool the soln. under the tap to about 15oC & then place it in a ice bath. Now add this cold soln. of NaNO3 into a cold solution ofSulphanilic Acid. Slowly with constant stirring.
Now pour this resulting solution slowly & with stirring into a 500 ml beaker containing 5ml of Conc. HCl & 30 gms Crushed ice.
Stir well this mixture for 10 min &maintain the temp. Below 10 oC using the ice bath.Diazobenzene sulphonate will soon separate out. Do not filter this off as they will dissolveduring the next stage of preparation.
Now dissolve 3.0 ml of Dimethyl Aniline into cold soln. of diazotized Sulphanilic acid withconstant stirring. Allow the mixt. To stand for 10 min the red or acid form of methylOrange will gradually separated.
After 10 min add slowly & with stirring 25 ml of 20% NaOH soln. the mixture will assumea uniform Orange color due to separation of the sodium salt of Methyl Orange in fineparticles.[add NaOH till Alkaline]
Now heat the contents almost to boiling stage & add 5.0gms of NaCl & again warm it at 80-90 oC. Until the salt has dissolved completely.
Allow the mixture to cool undisturbed for 15 min & then cool it in ice bath. Filter theproduct wash with water & recrystallized it from hot water.
Take 10 gms of powdered Acetanilide (dry) & 15 ml Glacial HAc in a 250ml beaker & add20 ml of Conc. H2SO4 with stirring the mixture becomes warm and clear solution isobtained.
Surround the beaker with freezing mixture of ice & salt and stir the solution mechanically
Now, take 5 ml fuming HNO3 & 3 ml Conc. H2SO4 in a 100 ml beaker cool the acid solution& transfer it in a separating funnel.
When the temp. of the solution from separating funnel drop by drop and maintain the tembelow 10 oC.
When all the mixed acid has been added remove the beaker from the freezing mixture andallow it to stand at room temperature for at least about 1 hour and then pour the reactionmixture into an ice containing water.
Crude P-Nitro Acetanilide is at once precipitated allow it to stand for 15 min. filter theproduct, wash it with cold water till free from acids[checks on litmus paper] dry it.Recrystallized the product with alcohol.
Step 2:- P-Nitro Acetanilide to P-Nitro Aniline [Acid Hydrolysis]
Requirement:- P-Nitro Acetanilide, 70% Conc. H2SO4[60ml Conc. H2SO4+45 ml H2O],10% NaOH or Conc. Ammonia Solution.
Procedure:-
Take 10 gm P-Nitro Acetanilide & 50 ml of 70% Conc. H2SO4 in a 250ml R.B.F attach areflux condenser & reflux it for about half hour [or until a test sample remains clear upondilution with 2 – 3 times its volume with water]
The P-Nitro Aniline is present in the liquid as sulphate. Pour the clear hot solution intocold water and precipitate the P-Nitro Aniline by adding excess of Conc. Ammoniasolution. Cool the mixture in ice water.
Filter the yellow crystalline P-Nitro Aniline. Wash with water & dry it. Recrystallize theproduct with hot water.
Take 5 gms of finely powdered Acetanilide in 15 ml of glacial HAc in R.B.F & cool it in icebath in another 100 ml beaker take 3 ml of bromine & dissolve it in 12 ml of HAc &transfer the solution slowly and with constant shake to cold solution of acetanilide which ispreserved in ice bath when all the bromine has been added the solution will turn an orangedue to the slight excess of bromine. All the reaction mixture into ice cold water in a 500 mlbeaker stir the mixture and add just sufficient NaHSO3 solution to remove the orangecolor. Filter the product, wash with ice cold water and dry it. Recrystallized the productwith Alcohol.
Take 7 gms P-Bromo Acetanilide & 15 ml Ethanol in a 250 ml R.B.F attached a refluxcondenser & heat the mixture till a clear solution is obtained [if necessary add morealcohol]
Meanwhile prepare a solution of 4 gms KOH in 10 ml of waters. Add this solution in a clearsoln. of R.B.F & reflux the contents for about 2 hours. Cool & add the contents of the flaskin a 250 ml beaker containing 100 ml ice cold water. The precipitate of P-Bromo Aniline isobtained. Filter the product and dry it. Recrystallized the product with rectified sprite.
Step 1:- Acetanilide to P-Nitro Acetanilide [Nitration]
Reaction:
Mechanism:
NHCOCH3
H
NHCOCH3
H
NHCOCH3
NO2
NHCOCH3
NO2
Step 2:- P-Nitro Acetanilide to P-Nitro Aniline [Acid Hydrolysis]
Reaction:-
NHCOCH3
NO2
P-Nitro Acetanilide
NH2
NO2
CH3COOH
P-Nitro Aniline
Acid Hydrolysis
Mechanism:
P-Bromo Aniline
Step 1:- Acetanilide to P-Bromo Acetanilide [Bromination]
Reaction:
Mechanism:
Step 2:- P-Bromo Acetanilide to P-Bromo Aniline
Reaction:
Mechanism:
ORGANIC ESTIMATION SEMESTER-II
1
Determine the % purity of Formaldehyde
Aim:- to determine the % purity of Formaldehyde by Hydroxyl Amine Hydrochloride MethodRequirement:- Formaldehyde, 10 % Hydroxyl Amine Hydrochloride soln., Exact 0.1N NaOHsoln., Bromo phenol blue IndicatorProcess:-
1. Blank Experiment:-Take 25 ml of distilled H2O in a conical flask. Add about 1 ml Bromo phenol blueIndicator & then add 10 ml soln. of 10 % Hydroxyl Amine Hydrochloride & titrate itagainst 0.1N NaOH soln. from the burrete yellow soln. changes to blue violet is the endpoint. Take 3 to 4 readings. Let the constant burrete reading “V2” ml.
2. Actual Experiment:-Weight out accurate about 0.270 to 0.300 gms of the given formaldehyde soln. in aweighting bottle. Transfer it to a conical flask by 25 ml dist. H2O. then add about 1 mlBromo phenol blue Indicator & then add 10 ml soln. of 10 % Hydroxyl AmineHydrochloride &allow to stand for 10 min & shake frequently. Then titrate the liberatedHydrochloride acid against 0.1N NaOH soln. from the burrete yellow soln. changes toblue violet is the end point. Take 3 to 4 readings.let the constant burrete reading “V1” ml.
Reaction:-
Observation:-Blank Estimation:-
Burette:- 0.1N NaOH Soln.
Flask:- 10 ml 10 % Hydroxyl Amine Hydrochloride + 25 ml dist. H2O
Process:-Blank estimation:-[standardization of NaOH]Take 25 ml of 1.5N NaOH in a 250 ml S.M.F & diluted it to 250 ml with dist. H2O. take 25 ml ofthe diluted soln. in a conical flask & titrate it against 0.1N HCl soln. from burette usingphenolphthalein as an indicator disappearance of pink color is the end point. Take 3 or 4 reading.Let the constant burette reading “A” ml.
Estimation of Acid:-Take 25 ml of given mixed soln of acid+amide in a 250 ml S.M.F & dilute it to 250 ml dist. H2O.Take 25 ml of this diluted soln.in a conical flask and titrate it against 0.1N NaOH soln. fromburette using phenolphthalein as an indicator. Appearance of pink color is the End point. Take 3to 4 burette reading. Let the constant burette reading “D” ml.
Actual Estimation [Estimation of Acid + Amide]:-Take 25ml of given mixed soln. of acid + amide in 250 ml R.B.F. add exact 25 ml of 1.5 NNaOH by pipette & 2 to 3 T.T dist. H2O attach on air condenser & refluxed the content on a sandbath. Cool the content & transfer the Hydrolyzed.Take 25 ml this diluted Hydrolyzed soln. in a conical flask & titrate it against 0.1N HCl soln.from burette using phenolphthalein as an indicator. Disappearance of pink color is the end point.Take 3 to 4 reading. Let the constant burette reading. Let the burette reading “B” ml.
ORGANIC ESTIMATION SEMESTER-II
3
Observation: Blank estimation [standardization of NaOH soln.]Burette:- 0.1N HCl Soln.Flask:- 25 ml dil. Soln. of NaOHIndicator:- phenolphthalein IndicatorEnd point:- disappearance of pink color
Estimation of Acid:-Burette:- 0.1N NaOH Soln.Flask:- 25 ml dil. Soln. of [Acid + Amide]Indicator:- phenolphthalein IndicatorEnd point:- Appearance of pink color
25 ml diluted refluxed [Hydrolyzed Soln.] required B = _______ ml 0.1 N HCl
Reaction:-
Now,
1. The amt. of NaOH soln. added in terms of 0.1 N HCl A = ______ ml2. The amt. of NaOH soln. unused in terms of 0.1 N HCl B = ______ ml3. The amt. of NaOH soln. used up for acid + amide in terms of 0.1 N HCl C = A – B ml
C = ________ ml4. The amt. of NaOH soln. used up for amide only in terms of 0.1 N HCl F = C – D ml
F = _______ ml
Now,
1000 ml 1 N NaOH = 1000 ml 1 N HCl = 59 gms Acetamide1000 ml 1 N HCl = 59 gms Acetamide1 ml 0.1 N HCl = 0.0059 gms AcetamideF ml 0.1 N HCl = 0.0059 X F gms Acetamide
G = _______ gms AcetamideAmt. of Acetamide in the given solution = G X 10
Y = ________ gms.
RESULT:-1. Normality of given NaOH solution = _______ N2. Amt. of Acid in the given solution = ________ (X) gms3. Amt. of Amide in the given solution = ________ (Y) gms
ORGANIC ESTIMATION SEMESTER-II
5
Determine the Amount of Acid + Ester
Aim:- you are given a mixed solution of acid + Ester. Determine the amount of acid & E in thegiven solution.
Process:-Blank estimation:-[standardization of NaOH]Take 25 ml of 1.5N NaOH in a 250 ml S.M.F & diluted it to 250 ml with dist. H2O. take 25 ml ofthe diluted soln. in a conical flask & titrate it against 0.1N HCl soln. from burette usingphenolphthalein as an indicator disappearance of pink color is the end point. Take 3 or 4 reading.Let the constant burette reading “A” ml.
Estimation of Acid:-Take 25 ml of given mixed soln of acid+Ester in a 250 ml S.M.F & dilute it to 250 ml dist. H2O.Take 25 ml of this diluted soln.in a conical flask and titrate it against 0.1N NaOH soln. fromburette using phenolphthalein as an indicator. Appearance of pink color is the End point. Take 3to 4 burette reading. Let the constant burette reading “D” ml.
Actual Estimation [Estimation of Acid + Amide]:-Take 25ml of given mixed soln. of acid + ester in 250 ml R.B.F. add exact 25 ml of 1.5 N NaOHby pipette attach water condenser & reflux it on water bath till hydrolysis is complete [ 1 and halfhour hour].Cool it and transfer the reflux solution in a 250 ml S.M.F & dilute it to250 ml with dist. H2O.Take 25 ml this diluted refluxed soln. in a conical flask & titrate it against 0.1N HCl soln. fromburette using phenolphthalein as an indicator. Disappearance of pink color is the end point. Take3 to 4 reading. Let the constant burette reading. Let the burette reading “B” ml.
Observation: Blank estimation [standardization of NaOH soln.]Burette:- 0.1N HCl Soln.Flask:- 25 ml dil. Soln. of NaOHIndicator:- phenolphthalein IndicatorEnd point:- disappearance of pink color
Estimation of Acid:-Burette:- 0.1N NaOH Soln.Flask:- 25 ml dil. Soln. of [Acid + Ester]Indicator:- phenolphthalein IndicatorEnd point:- Appearance of pink color
25 ml diluted refluxed Soln. required B = _______ ml 0.1 N HCl
Reaction:-
Now,
1. The amt. of NaOH soln. added in terms of 0.1 N HCl A = ______ ml2. The amt. of NaOH soln. unused in terms of 0.1 N HCl B = ______ ml3. The amt. of NaOH soln. used up for acid + ester in terms of 0.1 N HCl C = A – B ml
C = ________ ml4. The amt. of NaOH soln. used up for ester only in terms of 0.1 N HCl F = C – D ml
F = _______ ml
Now,
1000 ml 1 N NaOH = 1000 ml 1 N HCl = 88 gms Ethyl acetate1000 ml 1 N HCl = 88 gms Ethyl acetate1 ml 0.1 N HCl = 0.0088 gms Ethyl acetateF ml 0.1 N HCl = 0.0088 X F gms Ethyl acetate
G = _______ gms Ethyl acetateAmt of Ethyl acetate in the given solution = G X 10
Y = ________ gms.
RESULT:-5. Normality of given NaOH solution = _______ N6. Amt. of Acid in the given solution = ________ (X) gms7. Amt. of Ester in the given solution = ________ (Y) gms