Chem 31 PROCEDURES (Practicals)

Frances Mae Dela Cruz

PROCEDURES EXPERIMENT 1: SOLUBILITY BEHAVIOR OF ORGANIC COMPOUNDS * 5 drops of solvent to 1-2 drops of test compound

Organic Compounds water-soluble

water-insoluble

( + ether)

S1

(ether soluble)

(+ 5% NaOH)

5% NaOH soluble

5% NaOH insoluble

S2

(ether insoluble)

(+ 5% NaHCO3)

(+ 5% HCl)

M

(5% HCl insoluble w/ Nitrogen or Sulfur; amides)

5% HCl insoluble w/o Nitrogen or Sulfur (+ H2SO4)

I

(5% HCl insoluble; w/o reaction)

A1

(5% NaHCO3 soluble; strong acid)

N

(5% HCl soluble)

B

(5% HCl soluble; amines)

EXPERIMENT 7: ALCOHOLS, PHENOLS, AND ETHERS A. LUCAS TEST (Test samples: ethanol, isopropyl alcohol, tert-butanol, benzyl alcohol) 2 mL Lucas reagent (Note 1) in a small test tube.

Add 3-4 drops of the alcohol. Stopper the test tube and shake.

Note the time required for the formation of an emulsion or separate layers (Note 2).

A2

(5% NaHCO3 insoluble; weak acid)

B. OXIDATION OF ALCOHOLS (Test samples: ethanol, isopropyl alcohol, tert-butanol, benzyl alcohol, diethyl ether)

5 drops of test sample in a small test tube.

Add 1 drops of dilute, neutral KMnO4. *Warm the mixture = no decolorization

C. REACTION OF PHENOLS 4 pieces pH paper on a watch glass. Determine the pH of 0.1 M sol'ns each of phenol, pnitrophenol, and picric acid.

3 drops each of 0.1 M of phenol, β-naphthol, nitrophenol, and bromophenol in separate test tubes.

3 drops of phenol solution in a test tube. Add Br2 in water drop by drop by shaking. Observe the formation of a precipitate.

3 drops of phenol solution in a test tube. Add 1 drop of neutral KMnO4 (aq). Observe for the decolorization of MnO4.

Add 1 drop of FeCl3 sol'n. Note the color of the resulting sol'ns.

EXPERIMENT 10: ALDEHYDES & KETONES A. REACTION WITH 2, 4 – DNPH (2,4 DINITROPHENYLHYDRAZINE)

+ 5 drops 95% CH3CH2OH in 3 separate micro test tubes

+ 1 mL 2,4-DNPH in HCl solution to each of the 3 test tubes

+ 2 drops of acetone to test tube A

Record the color of the ppt. formed. * If no ppt. forms immediately, let it stand for a few minutes.

+ 2 drops of benzaldehyde to test tube B

B. TOLLEN’S TEST + 5 drops Tollens' reagent in 3 separate micro test tubes

+ 1 drop formalin to test tube A

+ 1 drop benzaldehyde to test tube C

Observe the formation of silver mirror. *If no reaction takes place, warm in a hot water bath. Aromatic aldehydes may require heating.

C. SCHIFF’S TEST: + 4 drops of Schiff's reagent in 3 separate test tubes.

+ 1 drop formalin to test tube A

+ 1 drop acetone to test tube B

+ 1 drop acetone to test tube B

Silver mirror formed --> pour out contents of the test tube and immediately rinse with water.

+1 drop of benzaldehyde to test tube C

Shake and record the color that develops within 3-4 minutes.

D. BENEDICT’S TEST

+ 5 drops of Benedict's reagent in 2 separate micro test tubes.

+ 2 drops of formalin to test tube A

+ 2 drops of benzaldehy de to test tube B

Test tubes in hot water bath --> formation of brick red ppt.

E. Iodoform Test

+ 5 drops of 10% NaOH in 2 separate test tubes.

+ I2 in KI sol'n dropwise into each mixture, shaking the test tubes after each addition * continue adding until --> pale yellow.

+ 2 drops of acetone to test tube A

Warm the solution in water bath. * If sol'n --> colorless after heating, add more I2 in KI sol'n and take not if the sol'n turns yellow again.

+ 2 drops of 95% CH3CH2OH to test tube B

Record the color of the sol'n after each addition of I2 in KI before and after heating.

F. EFFECT OF ACID CONCENTRATION ON THE RATE OF ADDITION OF 2,4-DNPH Weigh 0.15 g of 2,4DNPH in a beaker and dissolve in 15 mL acetone. Decant if there undissolved solids. (CLASS MONITOR)

+ 1 drop of 0.1M HCl to test tube C

+5 drops of prev. prepared 2,4DNPH sol'n into 4 different test tubes.

+ 1 drop of 1.0M HCl to test tube D

Keep 1 test tube (A) as standard.

+ 1 drop 0.1M CH3COOH to test tube B

Note the time of mixing and the time when crystals appear.

EXPERIMENT 11: CARBOHYDRATES A. OSAZONE FORMATION + 5 drops of the 5% solutions of SUCROSE, GLUCOSE, FRUCTOSE, and MALTOSE in separate test tubes After 30 mins., cool all in ice bath even, if some didn't form crystals

+ 10 drops of phenylhydrazine and 1 drop conc. HCl, each test tube

Heat all in boiling water bath

Record the order of crystal formation

Note the color and amount of the crystals formed for each sugar solution.

B. MOLISCH TEST

+ 5 drops of 1% glucose sol'n + 2 drops of Molisch reagent in a micro test tube

Mix the contents by gently shaking the test tube

Tilt, + 10 drops of conc. H2SO4 carefully. Observe the color of the junction of two liquids.

Repeat for 1% sucrose and starch solutions.

C. BIAL’S TEST + 5 drops of 1% ribose + 10 drops of Bial's reagent in a micro test tube

Heat until the solution begins to boil. Note the color of the product formed.

If the color is not distinct, dilute w/ 5 mL H2O, + 1 mL amyl alcohol. Observe color of alcohol layer.

Repeat the test with 1% glucose solution.

D. SELIWANOFF’S TEST + 5 drops of 1% solutions of glucose, fructose, and sucrose in separate micro test tubes

+ 10 drops of Seliwanoff's reagent each test tube

Heat the test tube in water bath.

After the 1st (+) result, observe the color of the solutions at 5-minute intervals for about 20 mins.

Record the time required for a (+) test each sample.

E. BENEDICT’S TEST FOR REDUCING SUGARS

+ 5 drops of 5 % sol'ns of glucose, fructose, maltose, sucrose, starch and distilled water in separate micro test tubes.

+ 1 mL Benedict's sol'n each test tube

Heat the test tubes in a boiling water bath and observe the resulting color change.

F. BARFOED’S TEST + 1 mL Barfoed's reagent to micro test tubes that gave a (+) result in Benedict's test.

Heat the test tubes in a water bath. Observe change in color within 10 MINUTES ONLY.

Arrange the sugars according to the degree of reducing power.

G. HYDROLYSIS OF POLYSACCHARIDES + 10 drops of 10% sucrose solution w/ 10 drops of distilled water in a micro test tube.

+ boiling stone and + 2 drops of conc. HCl

Boil gently for 3 mins.

Test for reducing property with Benedict's reagent.

Compare the result with unhydrolyzed sucrose sol'n.

Grind 0.5 g starch w/ little distilled water in mortar.

+ 1 drop of filtrate and mix it w/ 1 drop of I2 in KI sol'n in a spot plate. Note the color formed.

To the rest of the filtrate, + 5 drops of conc. HCl. Heat the solution in a water bath at 80⁰C.

Immediately get a drop of the heated starch sol'n and add it to a spot plate containing a drop of I2 in KI sol'n, record the resulting color.

Cool the solution and + 10% NaOH. Stir solution after each addition.

Test for reducing property with Benedict's reagent.

Compare the result with that of unhydrolyzed starch solution.

Cool the sol'n, then, neutralize with 10 % NaOH. *Stir the sol'n after each addition of NaOH.

Filter the paste and wash w/ minimum amount of distilled water.

Perfom the last step at 1minute intervals on new I2 in KI sol'ns on the spot plate until the resulting color for 3 successive tests are the same.

EXPERIMENT 12: CARBOXYLIC ACID AND ACID DERIVATIVES A. SOLUBILITY OF CARBOXYLIC ACIDS IN 5% NAHCO3 + 1 drops of glacial acetic acid + small pinch benzoic acid in 2 separate test tubes

+ 1 drop 0.5M NaHCO3 to each test tube

Record any observable change

B. TEST FOR ACETIC ACID + 2 drops of 2% NaOH + dropwise, glacial acetic acid until the solution is slightly acidic to litmus

D. FORMATION OF ESTERS

+ 2-3 drops 0.1M FeCl3 solution

Record any observable change (Note 1)

Fr: Carboxylic Acid + 5 drops of EtOH + 2 drops of glacial acetic acid in a micro test tube

+ 1 drop conc. H2SO4, Warm the solution

Note the smell of the product formed

Fr: Acyl Halides + 10 drops of EtOH + 2 drops of benzoyl chloride

Note the smell of he product formed

Stopper with cork and shake

E. HYDROXAMIC ACID TEST FOR THE ESTER GROUP + 1 drop of ethyl acetate + 1 drop of ether in a micro test tube

+ 1 drop of alc. NH2OH.HCl + 1 drop of alc. KOH

Heat over a smal flame to almost boiling and then cool a little

Acidify w/ alc. HCl

Esters: +2 mL ethyl acetate + 5 mL 25% NaOH in a 10 mL round bottom flask

Reflux the mixture for 30 mins. Observe the disappearance of the pleasant smell of the ester

+ 1 drop of 0.1M FeCl3 sol'n Record the color of the solution

F. HYDROLYSIS OF ACID DERIVATIVES Acetic Anhydride: + 5 drops of water + 3 drops of acetic anhydride in a micro test tube

Neutralize the sol'n with 6.0M HCL. Observe the emergence of the sour smell of the carboxylic acid formed

Moisten blue litmus with the sol'n and the note the color change

Amides: + small pinch of benzamide + 5 drops of 2% NaOH in a micro test tube

Heat the sol'n and note the odor of the gas evolved

C. CHEMICAL PROPERTIES OF HYDROCARBON Place a drop each of hexane, limonene and benzene into separate micro test tubes.

Add 2 drops of t-butyl chloride to each test tube. Mix thoroughly.

Allow the solution to wet the crystal and observe the change in the color of the crystal. Repeat the procedure using the rest of the test solutions.

Place 2 drops each of hexane, limonene, and benzene into separate micro test tubes. Add 1 drop of 0.05M Br2 in H2O into each test tube.

Incline the test tube and place small crystal of anhy. AlCl3 near its mouth. (Note: Powdery AlCl3 is no longer anhydrous)

Shake well and record observations.

Stopper the test tube in its position taking care that he crystal does not fall into the solution.

Place 2 drops of hexane, limonene and benzene into separate micro test tubes. Add 2 drops of 0.005M KMnO4 solution. Shake well and record observations.

Ignite 5 drops each of hexane, limonene and benzene contained in separate evaporating dishes in the hood. Observe the character of the flame (clear or sooty). Record observations.

RESULTS: I. ALCOHOLS, PHENOLS, ETHERS a. Lucas Reagent (ZnCl2 conc. HCl) Reactant Ethanol Isopropyl alcohol tert-Butanol Benzyl alcohol c. Reactions of Phenols Reactants Phenol + Br2 Phenol + KMnO4 Phenol + FeCl3 Nitrophenol + FeCl3 β-naphthol + FeCl3

b. Oxidation for Alcohols (KMnO4) Products / Results NVR

Products/ Results White Precipitate Brown Precipitate NVR Colored complex solution NVR

Reactant Ethanol Isopropyl alcohol tert-Butanol Benzyl alcohol Diethyl ether

Products/ Results NVR NVR

Bromophenol + FeCl3

Colored complex solution