Lab 01

Misr International University Faculty of Pharmacy Pharmaceutical Chemistry Department

Practical Pharmaceutical Organic Chemistry I

PHC 111

Dr. Ibrahim Elghamry

Contents Page Laboratory Safety

3

Tools and glassware

6

Identification and Classification of Organic Compounds

7

Collective Prospective: A- Physical Characterizations:

8

1- Conditions 2- Colour 3- Odour 4- Solubility 5- Dry heat

Working Sheets B- Chemical Characterizations: 1- Action of Soda lime 2- Action of 30% NaOH 3- Action of Concentrated H2SO4 4- Reaction with FeCl3

8 8 8 9 11 13 16 16 17 18

Working Sheets

19 21

Organic Compounds and Functional Groups Identification

24

1- Aliphatic hydrocarbons (Alkenes) Working Sheets 2- Alkyl Halides Working Sheets 3- Alcohols Working Sheets 4- Aldehydes and Ketones Working Sheets

24 26 28 30 33 37 40 44

5- Aliphatic Carboxylic Acids

47

A- Aliphatic Monocarboxylic Acids

47

B- Aliphatic Polycarboxylic Acids

50

Working Sheets 6- Salts of Aliphatic Carboxylic Acids

53 56

Working Sheets

57

Working Sheets for Final Practice

61

Prelab Exercise: Read this part carefully.

Locate the emergency eye-wash station,

Safety shower and fire extinguisher in your lab.

Check your safety glasses or goggles for size and transparency.

Learn: How to someone help and how to put out a clothing fire. First aid procedure for acid and alkali spills on the skin. The procedures for properly disposing of solid and liquid waste in your lab.

Important General Rules Know: The safety rules of your particular lab. The locations of emergency eye washes and safety showers.

NEVER: :! Eat, Drink, Or Smoke in the lab.

Do not Work alone. Perform no unauthorized experiments Distract your fellow workers; Horseplay has no place in the lab.

Eye protection is extremely important. Safety glasses of some type must be worn at all times.

Contact lenses should not be worn Because reagents can get under a lens and cause damage to the eye before the lens can be removed. It is very difficult to remove a contact lens from the eye after a chemical splash has occurred. Ordinary prescription eyeglasses do not offer adequate protection.

Dress sensibly in the lab. Wear shoes, not sandals or cloth-top sneakers. Confine long hair and loose clothes. Do not wear shorts. Do not use mouth suction to fill a pipette.

Wash your hands before leaving the lab. Do not use solvent to remove chemicals from your skin. This will only hasten the absorption of the chemical through the skin.

TOOLS & GLASSWARES

Identification and Classification of Organic Compounds Collective prospective

For the purpose of identification of an organic functional group as well as an organic compound, the following scheme for laboratory work should be applied

A) Physical Characteristics: 1. Condition 2. Colour 3. Odour 4. Solubility 5. Dry heat

B) Chemical Reactions: 1. Action of soda lime (on solid only) 2. Action of 30%NaOH 3. Action of conc. H2SO4 4. Reaction with FeCl3

C) General Class Reaction and Special Tests

A) Physical characteristics: 1. Conditions: The material is either Solid or Liquid

a) Solid: o Powder. o Crystalline (shiny) which may be micro or macro crystals (e.g. needles, plates, balls) according to the size

b) Liquid: You have to determine whether the liquid is •

True liquid or solution:

By using anhydrous copper sulphate in a watch glass then add few drops of the compound: ♦

True liquid: the colour does not change.

♦

Solution in water: the colour changes from green to blue.

•

Mobility: viscous, oily

2. Colour: o The colour of the original sample is noted o Compounds may show colour due to impurities or chromophoric groups o The colour observation may help to expect the unknown compound.

3. Odour: o Some organic compounds have characteristic odour,

(Strong smelling is avoided) e.g. Alcoholic odour: methanol, ethanol Bitter almond odour: benzaldehyde Mice like odour: acetamide Pleasant fruity odour: esters Vinegar odour: acetic acid.

4. Solubility: Solubility is used to indicate the nature of the organic compound & its functional group, by trying solubility at room temperature in: 1-H2O

2- dilute NaOH

3- dilute HCl

♦Solubility Test: 1- Few amount of solid (finely powdered) or (0.2 mL) of liquid in a test tube. 2. Add 5 mL solvent (H2O, dilute NaOH or dilute HCl) shake well at room temperature, then notice the change:

A) Compounds soluble in water: If the compound dissolves in water, test the aqueous solution with litmus paper and observe whether it is: Acidic (blue→red), basic (red→blue) or neutral (no change)

For example:

1. Aqueous solution acidic to litmus paper: carboxylic acids, phenols, salts of amines. 2. Aqueous solution basic to litmus paper: sodium or potassium salts of carboxylic acids 3. Aqueous solution neutral to litmus paper: alcohols, aldehydes, ketones or sugars.

B) Compounds insoluble in water and soluble in 10% NaOH: ♦ If the compound is insoluble in water, try solubility in dilute NaOH •

If the compound is soluble in 10% NaOH, and reprecipitate by adding conc. HCl, this indicates it is acidic substance

For example: Higher aliphatic acids

Sodium carbonate test: •

This test is carried out to differentiate between strong and weak acidic organic compounds.

•

This test is carried out for compounds:

a) Soluble in water & acidic to litmus paper b) Insoluble in water & soluble in 10% NaOH

Procedures: 1. In a test tube, with 2 mL of Sodium carbonate solution add few crystals of the substance. (warm if necessary) 2. Note the effervescence: •

If there is effervescence and evolution of CO2 then the substance is strong acid e.g. carboxylic acids or aniline salts

•

If there is no effervescence then the substance is weak acid eg: phenols

C) Compounds insoluble in water, dilute. NaOH and soluble in dilute HCl •

If the compound is insoluble in dilute NaOH, try solubility in dil HCL

•

If the compound is soluble in dilute HCl, and reprecipitate by 30%

NaOH, this indicates it is basic substance e.g.

Aromatic amines (Aniline,

Toluidine,..)[NOT INCLUDED IN THIS COURSE]

D) Compounds insoluble in dilute. NaOH and dilute HCl: •

if the compound is insoluble in all above reagents then this compound is neutral

5) Dry heat: •

heat a small portion of the organic compound on inverted porcelain lid or broken glass, note carefully: 1. Inflammability: a) Inflammable or non inflammable

(Inflammable means that when you remove the substance from the flame it will catch fire) b) Luminous or non luminous c) Smoky or non smoky: e.g.

I- Unsaturated, and higher aliphatic compounds give

yellow

and

smoky flame II- Lower aliphatic compounds give yellow and non-smoky flame III- Lower alcohols: Give clear bluish flame

2.

Change in appearance: As seen (melts, blackens, charring, swelling, evaporates)

3. Change in odour: As detected (ammonia odour, burnt sugar odour,…) 4. Change in colour:

• Sodium salts: Golden yellow flame • Potassium salts: Violet flame • Organic halogen compounds: Green flame 5. Residue: Notice, if there is a residue (remaining) after ignition or not •

if the residue is present, check if the residue is A. Metallic residue: produced from ignition of metallic derivatives e.g. alkali salts of carboxylic acids B. Nonmetallic residue: residue of carbon which may be very difficult to burn off completely

Procedure: Allow the residue to cool then add few drops of dilute HCl and observe the effervescence which appears in case of metallic residue.

Working Sheet Sample 1:

Chemical Name:

Chemical Structure:

Physical Characterizations ………………………………………………………………………………………… …….................................................................................................................................. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .........................................................................................................................................

Working Sheet Sample 2:

Chemical Name:

Chemical Structure:

Physical Characterizations ………………………………………………………………………………………… …….................................................................................................................................. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ........................................................................................................

Working Sheet Sample 3:

Chemical Name:

Chemical Structure:

Physical Characterizations ………………………………………………………………………………………… …….................................................................................................................................. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ..........................................................................................................................................

B. Chemical Characteristics:

1.

Action of Soda-Lime: (On Solids only) •

Soda lime is a fused mixture of NaOH and CaO.

•

Its main action is based on the action of NaOH, while CaO decompose or dehydrate the substance.

•

This test is done on solid only.

•

If your compound is a liquid, this test is not done.

Procedure: In a mortar, mix one part of the compound with three parts of soda lime, grind and notice any change at room temperature (r.t.) first (odour or any change in the nature of the sample). If no odour is produced at room temperature, transfer part of the mixture into a dry test tube and heat (CAUTION!!!!).

The action of soda lime on organic compounds involves the following reactions: •

Decarboxylation

e.g. Carboxylic acids give parent hydrocarbon. ⎯⎯⎯→

RCOOH •

R-H

Hydrolysis

e.g. Amides give ammonia odor. R-CO-NH2 •

⎯⎯⎯→

R-COONa + NH3

Dehydration

e.g. Carbohydrates give burnt sugar odor due to the removal of water molecules. •

Neutralization

e.g. Amine salts give free amines. R-NH2.HCl

⎯⎯⎯→

R-NH2

Some important observations are summarized in the following table: Observation

Expected substance

Ammonia odour at r.t.

Ammonium salt of carboxylic

acids Ammonia odour on hot

Amides or imide

Fishy odour at r.t.

Salts of amines

Burnet sugar like odour on hot

Carbohydrates

aliphatic

and

some

hydroxyl acids and

their salts. Hydrocarbons evolved on hot

2.

Carboxylic acids or their salts

Action of 30% NaOH: The action of 30% NaOH is done on both solids & liquids. Procedure: 30% NaOH is added directly on the compound in a test tube. Note any reaction on cold (odor-color). If no reaction at room temperature, then heat and observe any change.

I-Odour: Some important observations are summarized in the following table: Observation

Expected substance

Ammonia odour at r.t.

Ammonium salt of carboxylic

acids Ammonia odour on hot

Amides or imide

II-Observation of any change in: Some important observations are summarized in the following table:

Observation

Expected substance

Brown resinous material on hot

Aliphatic aldehydes

Yellow solution which rapidly

Polyhydroxy compounds

darkens on shaking White emulsion at r.t.

Some esters

The action of 30% NaOH on organic compounds involves the following reactions: • • •

Neutralization: e.g.: amine salts to give free amines. Reaction with NH4 salts liberates NH3. Polymerization: e.g. acetaldehyde, gives yellow resin.

3- Action of concentrated. H2SO4: The action of conc. H2SO4 is done on both solids & liquids. Concentrated. H2SO4 is added directly on the compound. Procedure: 1- In a dry test tube, place a small amount of the compound then add 1 mL conc.H2SO4 (CAUTION!!!!!). 2- Note the reaction first on cold then warm gently.

Precautions in dealing with conc.H2SO4 :

™ Never use large quantities of conc.H2SO4. ™ Never heat excessively (never boil). ™ Discard in running water slowly.

Some important observations are summarized in the following table:

Observation

Expected substance

Evolution of carbon monoxide

Formic or oxalic acids and their

salts without blackening Yellow colour, effervescence and

Citric acid and its salts

evolution of carbon monoxide Blackening without effervescence

Polyhydroxy

compounds

(resorcinol) Rapid charring without effervescence

Tartaric or tartarate

Evolution of pungent vapours without

Simple carboxylic acids and their

blackening and effervescence

derivatives

4- Reaction with FeCl3: •

FeCl3 is a yellow colored solution.

•

This test is done on solutions only (even if the compound is a liquid)

•

The observation is usually a change in color. ♦Colorations are frequently given by the reaction of FeCl3 with :

a.

Acids & their salts.

b.

Phenols

[NOT IN THIS COURSE]

c.

Amines

[NOT IN THIS COURSE]

Procedure: 1- In a test tube add a small amount of the substance (as a solution) then add

three drops of ferric chloride.

2- Notice any change in color. ™ This test depends on solubility results: NOTE: Few amount of solid is dissolved in excess amount of solvent. Dissolve in the proper solvent The proper solvent must:

i) Dissolve the compound completely. ii) Not interfere with the reaction. If the compound is neutral, basic, or weakly acidic:

If the compound is strong acid: (free acid) It must be neutralized by preparing a neutral solution, (N.S.) as follows:

1. In a beaker, add small amount of the acid + 25mL water + red Litmus paper (L.p.). Then add NH4OH dropwisely till the red L.p. turns blue. 2. Boil the beaker on direct flame to evaporate excess NH3. 3. Check the absence of ammonia (notice the color of the L.p.) then cool. 4. Take some of the prepared N.S. in a test tube then add 3drops FeCl3. Note: When a lemon yellow color is produced, blank solution should be prepared, to

differentiate between the lemon yellow color and the yellow color of FeCl3.

Blank Experiment: Take 3 mL H2O in a test tube, add 3 drops FeCl3 then shake. Compare between the colour produced with the compound and the color of the blank experiment.

Working Sheet Sample 1:

Chemical Name:

Chemical Structure:

Physical Characterizations ………………………………………………………………………………………… …….................................................................................................................................. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ......................................Chemical Characterizations .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ....................................................................................

Working Sheet Sample 2:

Chemical Name:

Chemical Structure:

Physical Characterizations ………………………………………………………………………………………… …….................................................................................................................................. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ......................................Chemical Characterizations .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ....................................................................................

Working Sheet Sample 3:

Chemical Name:

Chemical Structure:

Physical Characterizations ………………………………………………………………………………………… …….................................................................................................................................. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ......................................Chemical Characterizations .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ....................................................................................