ASSIGNMENT

TOPIC:- “SYSTEMATIC QUALITATIVE ORGANIC ANALYSIS”

LECTURER NAME:- A . SENTHIL RAJA

SUBJECT:-PHARMACEUTICAL ORGANIC CHEMISTRY

DEPARTMENT OF PHARMACEUTICS, IT-BHU

DATE:- 12-03-2009

PREPARED BY:- VERIFIED BY:-

GANGINENI RAVI TEJA A. SENTHIL RAJA

08421EN008

Personal information:

Name:................................................ college code:……………..

Class:................ college name:……………………………………………

M.PHARM DUAL DEGREE PART-I

REFERENCES:-

1. EXPERIMENTAL ORGANIC CHEMISTRY(Principles and Practice)

Lawrence M. Hard Wood and Chrishtoper J. Moody chapter- 1

2. Qualitative Organic Analysis by Scott Frees[Rampo College of New Jersey,Mahwah,NJ07430]

3. http://wwwchem.uwimona.edu.jm/lab_manuals/c10expt25.html

4. Practical Chemistry

Systematic qualitative organic analysis

ContentsSection-A:-

Preliminary tests

a.Physical examination b.Solubility analysis c.Tests for Aliphaticity/Aromaticity d.Tests for unsaturation/saturation

Section-b:-

Tests for special elements N,S,P,X(HALOGENS).

Section-C:-

Tests for Functional groups

Section-d:-

Preparations of derivatives

Section-A:-

Preliminary testsexperiment Observation inferencea.physical examination

1.state

2.nature

3.Colour

1.liquid/solid

2.crystalline/amorphous

3.coloured/colourless

1. a)Liquid-alcohols, aldehydes,ketones simplehydrocarbonsand acids,nitro compounds,phenolsand amines.b)solids-carbohydrates,simple acids,some phenols,amides and anilides,nitro compounds,amines,phenols,quinones.

3. a)coloured-nitro compounds,amines, phenols,quinones.

b)colourless- alcohols, aldehydes,ketones simplehydrocarbonsand acids, carbohydrates,simpleacids,some phenols,amides and

4.odour 4. a)carbolic smell b)smell of bitter almonds c)pleasant smell d)spirituous smell e)pungent smell

anilides.4.

a)phenols. b)benzaldehyde,nitrobenzene. c)esters. d)alcohols. e)formic acid,formalin.

b)solubility analysis:-unknown

Mono functional compoundswith less than 5 carbon

compounds,

ionic compounds

Inference:-may be

H

soluble

Aq.NaOH

Aq.NaHCO3

Insoluble

soluble

Insoluble

Aq,HClsoluble

insolu

ble

(a).hydrophilic groups,--COOH,-NH2,-OH

c)Tests for Aliphaticity/Aromaticity:-

Experiment Observation InfererenceTake a small portion of the given compound on a glass rod and ignite it over free flame

Burns with

a)sooty flame

b)yellow and non sooty flame

c)chars

May be

a) an aromatic compound

b) aliphatic compound

c) carbohydrate , hydroxy acid or sulphonic acid

d) nitrogenous compounds like urea

May be-COOH,-SO3H,Highly acidic phenols

Phenols , Thio-phenols.

Aliphatic amine,primary aromatic amine.

Conc,H2SO4

Oxygen containing compounds,alkenes,alkynes,activated aromatic compounds.

soluble

In

soluble

Observation inference

a)Insoluble in Aq.NaHCO3 and soluble in 2M.Aq a) phenol or enolic compounds

NaOH (1,3diketone,Keto-enol tautomerism)

b)an intensification or appearanceof colour b)may be aromatic

on dissolution inbase

c)solublein2MHCl AND and any change in colour may be amino compound,hetero atomic

base, aromatic amine

Alkanes,halo alkanes,un activated aromatic compounds

d)smell of ammoniaNitration test :-Take 1ml of conc. H2SO4 and1ml of conc. HNO3 in a test tube and add small portion of the compound

a) Any colourationb) No coloration

a) Maybe aromaticb) may be aliphatic

d) Tests for un saturation/saturation:-

Experiment Observation Inference a) reaction with Bromine:-Take solution of the compounds in water and add to it few drops of bromine water .alternatively take a solution of the compound in CCl4

and add to it a solution of bromine, shake well

i. De colourisation

ii. A ppt .is obtained

i. Unsaturated compound

ii. Amines and phenols

b) reaction with

alkalineKMnO 4 :- Dissolve a little of the substance in water or acetone. Add to it1ml. of dil. sodium carbonate solution and add a few drops of KMnO4 solutionand shake well.

De colourisedPresence of unsaturation

Section-b:-

Tests for special elements N,S,P,X(HALOGENS).

To elemental analysis of an unknown compound there are two methods

(a).Lassaignes Sodium Fusion Extract.

(b).Middleton’s method.

(a).Lassaignes Sodium Fusion Extract:-

Materials required:-

Sodium metal,iron(ll)sulphate,Aq.sulphuric acid(5%),Aq.disodium penta cyano nitrosyl ferrate(0.1%)(Sodium nitro prusside,Sodium nitro ferri cyanide), Aq.nitric acid(5%),Aq.silver nitrate solution(5%),

Chlorine water { An equivalent reagent may be prepared from 10% aq.NaOCl, acidified with 1/5th of volume of 10%aq. HCl }.

CCl4 ,ammonia solution(concentrated).ammonium molybdate reagent [ prepared by dissolving 4.5 grams(NH4)2MoO4 in 4ml of conc. ammonia solution ,adding 12gm NH4NO3 and diluting the mixtureto 100ml.] zirconium alizarin red S paper

Preparation of Sodium Fusion Extract :-

a) Take a ignition tube and hold it with tongs.transfer 200-300 mg of sodium metal with the help of forcibs.

b) Melt the Sodium metal in the ignition tube.

c) Pinch of substance(or) 2-3 drops of the compound should be added to the molten sodium metal.

d) Heat the ignition tube till it is red hot and place the tube slowly in a50-60 ml of cold waterin a bowl shape.

e) A wire gauge should be used for safety so that no broken part of the ignition tube comes out the bowl.

f) Triturate the mixture and transfer it to abeaker , heat for 15-20 min and the solution should be filtered.

g) The colourless filtrate obtained should be testedfor the ele ments.

h) The solution should be taken in five test tubes in small portions.

Experiment Observation Inference Sulphur detection:-

(a) Add 2ml of the di sodium penta- cyano nitrosyl ferrate stock solution

A purple coloration which fades slowlyPresence of sulphur

to one of the test tubes.(b) If the stock solution is not

available,dissolve small crystal of the reagent in 2ml of distilled water and this to your sample.

Phosphorus detection:-Acidify the sample in the fifth test tube with dilute HNO3 and boil the mixture for 2min.Add an equal volume of the ammonium molybdate solution. Warm the mix to app 40-50 C and allow to stand

Formation of yellow ppt. Presence of phosphorus

Experiment Observation InferenceNitrogen detection:-Add 200mg of iron (ll)sulphatetothe second test tube,heat the solutiontothe boiling and add sufficient dil.H2SO4 to dissolve anyppt and make the solution acidic.

If the condensationhas been formed ,filter the mixture , with distilled water and examine the residuefor blue colouration

The formation of deep blue ppt. (or)colouration

Presence of nitrogen

Halogen detection:-Add the nitric acid to the solution to make it acidic boil until its volumehas been halved(removes HCN or H2Swhich interferethe test.(The above test may be skipped when nitrogen and sulphur is absent.)

Experiment Observation Inference Add 1ml of AgNO3 solution to this mixture.

White or yellow ppt. Presence of halogen

0.5ml of CCl4was added to the another test tube. Add chlorine water dropwiseto

Brown colourisation in bottom layer Presence of bromine

themixtureAdd excess of chlorine water drop wise Purple coloration(disappears after some

time)iodine

A sample which trreared with AgNO3 Gives a white ppt.No colouration obtained with Cl2 water

Presence of chlorine

Acidify 2ml of filtrate with glacial acetic acid reduce the volume to one half by boiling and spot the resultant mixture onto zirconium alizarin red S-paper

Appearance of yellow spot(presence of phosphate or sulphate interfere the result)

Presence of flourine

(b).Middleton’s method:-

Sodium carbonate- zinc fusion.

In this method N and X are converted to zinc sulphide which is decomposed with dilute acid and the H2S liberated detected with lead acetate paper.

Materials:-

Sample,zinc powder-sodium carbonate mixture. aq. Lead (II) acetate (5%) reagents N and X(halogen)are of same as lassaign’s fusion extract.

Zn-Na2CO3 mixture prepared as stock reagent by grinding intimately together 25gm anhydrous Na2CO3 and

50gm of high purity grade zinc powder. (blank test halogens and sulphur should be made.)

(a) Fusion:- In a test tube mix unknown substance with sufficient of Zn-Na2CO3 reagentadded 1cm depthand mix 2cm of reagent further mixing should be donePlace 40ml of water in the evaporating dish torecieve the hot tube after the fusion and place this behind the safety screen , with the tube held horizontally ,gently heat the reagent nearest the open end of the tube and slowly increase the rate of heating until the whole mass is at red hot (evolution of gases are seen and the ejection of red hot solid stop heating temporarily).

Finally heat the tube in vertical position and then drop it inti the water contained in the evaporating dish for 2min and then filter the hot mixture.

Experiment Observation InferenceSulphur detection:-Wash out the evaporating dish and return the residue in the filter paper to it add about 10ml of 5% HCl to the residue and covere the evaporating dish with a filter paper moistened with lead acetate solution.

Formation of brown stain on the paper Presence of sulphur

For P,N,X(halogens)same as that of lassaigne’s fusion extract.

Section-C:-

Tests for Functional groups

Experiment Observation InferenceCarboxylic acids:-Acids are soluble in water and dissolve the acid in methanol, add carefully 5% saturated NaHCO3 solution

Vigorous effervescence -COOH is present

ESTERS:-(a)FeCl 3 testDissolve a drop or few small crystals of the compound in 1ml of 95%ethanol and 1ml of HCl . note the colour produced When 1 drop of 5% iron chloride is added.

Any colour Hydroxamic acid test not applicable

(b)hydroxamic acid test:- (a) mix 1 drop or several small crystals of the compound with 1ml of 0.5M NH2OH hydrochloridein 95%ethanoland add 0.2 ml of 6M aq. NaOH. (b) heat the mixture to boiling and after the solution has cooledslightly add2mlof 1M HCl. (c) if the solution is cloudy .add 2ml of 95%of ethanol.observe the colour produced when 1 drop of 5%iron (lll)chloride solution is added.

(d)if the resulting colour does not persists, continue to add the reagent dropwise until the observed colour pervades the entire solution .usually 1drop of iron (lll)chloridesolution is necessary.

(e) compare the colour with that produced in the test ‘a’.

(f) a positive test will be a distinct burgundy or magenta colour as compared with yellow colour observed when the original compound is tested with iron (lll)chloride solution in the presenceof acid (parallel test is always advised).

Experiment Observation Inference

Amides:-Boil 0.5 gm of the compound with 5ml of 10%NaOH solution

NH3 is evolved(tested with a rod dipped in conc.HCl will give fumes)

Amide(-CO-NH2) is present

Aldehydes and ketones:-(a)2,4-Dinitrophenyl hydrazine:-0.2-0.3gm (2-3ml) of compound and add (2-3ml) of 2,4-Dinitrophenyl hydrazine

(b)Iodoform test:-Add four drops or 0.1 g of unknown to a test tube. Add 5 mL of dioxane, and shake until unknown dissolves. Add 1 mL of 10% NaOH solution, and then slowly add the iodine-potassium iodide solution with shaking, until a slight excess yields a definite dark color of iodine. Heat the mixture to 60oC.The addition of iodine is continued until the dark color is not discharged by 2 minutes of heating at 60oC. Add a few drops of 10% NaOH solution to discharge iodine color. Now fill the test tube with water and let stand for 15 minutes. Filter the precipitate and check the melting point; iodoform melts at 119-121oC.

(a) Yellow or red ppt.

(b)Formation of solid iodoform (yellow)

Presence of aldehyde

Presence methyl ketone group

Aldehydes only:-(a)Fehlings solution:- Add2-3 drops (0.05gm) of sample andadd 2-3 drops of reagent and heat on boiling water bath for 3-4 minutes. (b)tollens reagent(ammoniacal AgNO3 solution):- Add 2-3 drops of the compoundin methanol 2-3ml of tollens solution containedina very cleantest tube

Yellow or red colouration

Silver mirror

Presence of aldehyde

Presence of aldehyde

Alcohols:-(a)Jones reagent:-Place 1ml of acetone in a test tube and dissolve one drop of liquid or long of solid alcohol or aldehyde in it. Add one drop of jones reagent(CrO3-H2SO4 in H2O) to the acetone solution and shake the tube to mix the contents well

(b)Lucas reagent test:-To 0.2 mL or 0.2 g of the unknown in a test tube add 2 mL of the Lucas reagent(ZnCl2 - conc. HCl ) at room temperature. Stopper the tube and shake vigorously, then allow the mixture to stand. Note the time required for the formation of the alkyl chloride, which appears as an insoluble layer or emulsion.

(a) Orange colour(2s)(b) Green or blue green ppt.

(2s)(c) No reaction upto 3min

(a) immediate to 2-3 minutes (b) 5 -10 minutes (c) Solution remains clear

(a) Primary alcohol(b) Secondary alcohol

(c) Tertiary alcohol

(a) 3o alcohols(b) 2o alcohols(c) 1o alcohols

PHENOLS:-(a)Bromine water:-Dissolve or suspend about o.o5 gm of the compound in 2ml of dil.HCl and Br2 water drop wise until the bromine remains its colour

(b)FeCl3 test:-Dissolve 0.05 gm of the compound in2ml of water (or a water, ethanol mixture when the compound is water insoluble) and add an aqueous solution of FeCl3 drop wise

A white ppt.

Observe any colour changes (red ,purple, blue ,green)

Presence of phenolic group

Presence of phenolic group

Amines:-(a) Reaction with nitrous

acid:-dissolve the amine (0.5ml) in conc.acid(mostly H2SO4)and water(3ml)and cool the solution to 0-

(a) N2 is evolved

(b) Diazonium salt is formed

(c) Yellow oily nitrosamines are

(a) Alphatic amine

(b) Aromatic amine

(c) aliphatic and aromatic

5C in an ice bath for 5 min. add a cold solution of sodium nitrite(0.5gm) in water(2ml)from a dropper;with swirling the test tube still keeping in the ice bath.

(b) Reaction with Benzene sulphonyl chloride:-Place 0.5 ml of the compound, 15-10 ml of 5%NaOH and stopper the tube and shake until odour of the sulphonyl chloride is disappeared. The solution must be alkaline.

If ppt. occurs in the above solution dilute with 10ml of water and shake well

If no ppt. acidify with conc. HCl

generally formed. (d) green solid p-nitroso compounds (if p-position unsubstituted).

No reaction

ppt. not dissolve

congo red colouration

(d) Dialkylanilines(aromatic)

Tertiary amine

Secondary amine

Primary amine

Section-d:-

Preparations of derivatives

CLASS OF COMPOUND DERIVATIVES1. ALCOHOLS 3,5-dinitrobenzoate2. PHENOLS benzoate, acetate, bromo-derivative3. ALDEHYDES AND KETONES semicarbazone, 2,4-dinitrophenyl-hydrazone, oxime4. ACIDS anilide, amide, p-toluidide.5. AMINES benzoyl, acetyl and sulphonamide derivativesMETHODS FOR THE PREPARATION OF DERIVATIVES

ALCOHOLS:-

(i) 3,5-Dinitrobenzoates3,5-Dinitrobenzoyl chloride is usually partially hydrolysed and should be prepared in the pure state by heating gently a mixture of 3,5-dinitrobenzoic acid (1 g) and phosphorus pentachloride (1.5 g) in a dry test tube, until it liquifies (5 min).* The liquid is poured on a dry watch glass and allowed to solidify. The phosphoryl chlorides are removed by pressing the solid with a spatula on a wad of filter paper. The residual acid chloride is suitable for immediate use in the preparation of the derivatives.

*Work under fume hood. Fumes are irritating to the eyes and nose.

The 3,5-dinitrobenzoyl chloride is mixed with the alcohol (0.5 - 1 mL) in a loosely corked dry test tube and heated on a steam bath for about 10 min. Secondary and tertiary alcohols require up to 30 min. On cooling add 10 mL sodium hydrogen carbonate solution, stir until the ester crystallises out, and filter at the pump. Wash with a little carbonate solution, water and suck dry. Recrystallise from the minimum hot ethanol or light petroleum. Cool slowly to avoid the formation of oily droplets of your ester.

PHENOLS

(i) Benzoates (Schötten-Baumann method):-To the phenol (0.5 g) is added 5% sodium hydroxide (10 mL) in a well-corked boiling tube or a small conical flask. Benzoyl chloride (2 mL) is added in small quantities at a time, and the mixture shaken vigorously with occasional cooling under the tap or in ice-water. After 15 min the solid benzoate separates out: the solution should be alkaline at the end of the reaction; if not alkaline, or if the product is oily, add a solid pellet of sodium hydroxide and shake again. Collect the benzoate, wash thoroughly with cold water, and recrystallise from alcohol or light petroleum.

(ii) Acetates:-Acetates of many simple phenols are liquids; however, this is a suitable derivative for polyhydric and substituted phenols. The phenol (0.5 g) is dissolved in 10% sodium hydroxide solution and an equal quantity of crushed ice is added, followed by acetic anhydride (2 mL). The mixture is vigorously shaken in a stoppered test tube until the acetate separates. The product is filtered and recrystallised from alcohol.

(iii) Bromo derivatives:-The phenol (0.3 g) is suspended in dilute hydrochloric (10 mL) and bromine water added dropwise until no more decolourisation occurs. The bromo derivative which precipitates out is filtered off and recrystallised from alcohol.

ALDEHYDES AND KETONES

(i) Semicarbazones:-Dissolve semicarbazide hydrochloride (1 g) and sodium acetate (1.5 g) in water (8 - 10 mL), add the aldehyde or ketone (0.3 mL) and shake. Shake the mixture for a few minutes and then cool in ice-water. Filter off the crystals, wash with a little cold water and recrystallise from methanol or ethanol.

(ii) 2,4-Dinitrophenylhydrazones:-Suspend 0.25 g of 2,4-dinitrophenylhydrazine in 5 mL of methanol and add 0.5 mL of concentrated sulphuric acid cautiously. Filter the warm solution and add a solution of 0.2 g of the carbonyl compound in 1 mL of methanol. Recrystallise the derivative from methanol, ethanol or ethyl acetate.

(iii) Oximes:-Hydroxylamine hydrochloride (0.5 g) is dissolved in water (2 mL). 10% sodium hydroxide (2 mL) and the carbonyl compound (0.2 - 0.3 g) dissolved in alcohol (1 - 2 mL) are added, the mixture warmed on a steam bath for 10 min and then cooled in ice. Crystallisation is induced by scratching the sides of the test tube with a glass rod. The oximes may be crystallised from alcohol.

ACIDS

(i) Amides, anilides and p-toluidides:-The acid (0.5 g) is refluxed with thionyl chloride (2 - 3 mL) in a fume cupboard for about 30 mins.* It is advisable to place a plug of cotton wool in the top of the reflux condenser to exclude moisture. The condenser is removed and the excess of thionyl chloride is distilled off (b.p. 78 ). The acid chloride thus produced is treated with concentrated ammonia solution (5 mL) or aniline (0.5 - 1 mL) or p-toluidine (0.5

- 1 g), when the solid derivative separates out. It is collected and recrystallised from alcohol adding decolourising charcoal if found necessary.

*Alternately use PCl5 to form the acid chloride.

AMINES

(i) Acetyl derivatives (acetamides):-Reflux gently in a small dry flask under a dry condenser the amine (1 g) with acetic anhydride (3 mL) for 15 min. Cool the reaction mixture and pour into 20 mL cold water. Boil to decompose the excess acetic anhydride. Cool and filter by suction the insoluble derivative. Recrystallise from ethanol.

(ii) Benzoyl derivatives (benzamides):-Suspend 1 g of the amine in 20 mL of 5% aqueous sodium hydroxide in a well-corked flask, and add 2 mL benzoyl chloride (fume hood!), about 0.5 mL at a time, with constant shaking. Shake vigorously for 5 - 10 min until the odour of the benzoyl chloride has disappeared. Ensure that the mixture remains alkaline. Filter off the solid derivative, wash with a little cold water and recrystallise from ethanol.

(iii) Benzenesulphonamides:-To 1 g of the amine in 20 mL of 5% sodium hydroxide solution in a well-corked flask add 1 mL benzenesulphonyl chloride (fume hood!). Shake the mixture until the odour of the sulphonyl chloride disappears. Check that the solution is alkaline. Acidify if necessary to obtain the precipitated derivative. Concentrated hydrochloric acid added dropwise should be used. Filter the product, wash with a little cold water and suck dry. Recrystallise from ethanol.