Classification Tests for Hydroxyl- and Carbonyl-containing Compounds PDF

PRAYER BEFORE CLASS Holy Spirit, Divine Creator, true source of light and fountain of wisdom! Pour forth your brilliance upon my dense intellect, dissipate the darkness which covers me, that of sin and of ignorance. Grant me a penetrating mind to understand, a retentive memory, method and ease of le...

PRAYER BEFORE CLASS Holy Spirit, Divine Creator, true source of light and fountain of wisdom! Pour forth your brilliance upon my dense intellect, dissipate the darkness which covers me, that of sin and of ignorance. Grant me a penetrating mind to understand, a retentive memory, method and ease of learning, the lucidity to comprehend, and abundant grace in expressing myself. Guide the beginning of my work, direct its progress and bring it to successful completion. This I ask through Jesus Christ, true God, and true man, living and reigning with You and the Father, forever and ever. Amen.  UST General Santos Post Laboratory Discussion: Classification Tests for Hydroxyl- and Carbonyl-containing Compounds Inorganic and Organic Chemistry Laboratory Unit Intended Learning Outcome: At the end of the unit, the student must be able to: ❖ distinguish whether a compound is hydroxyl- or carbonyl-containing; ❖ differentiate the three types of alcohols; ❖ differentiate aldehydes from ketones; and ❖ explain the mechanisms involved in the differentiating tests. Topic Outline ❖ Classification Tests ⮚ Solubility of Alcohols in Water ⮚ Ester Formation ⮚ Lucas Test ⮚ Oxidation of Alcohols using Acidic Potassium Dichromate ⮚ 2,4-Dinitrophenylhydrazine Test ⮚ Fehling’s Test ⮚ Tollens’ Silver Mirror Test ⮚ Iodoform Test  UST General Santos Alcohols Classification Tests for Hydroxyl- and Carbonyl- containing Compounds Water Solubility - as carbon chain increases beyond three (3) carbons, solubility in water rapidly decreases Solubility of Alcohols in Water ALCOHOL SOLUBILITY IN WATER Ethanol Soluble Methanol Soluble Ester Formation CARBOXYLIC ACID ALCOHOL ESTER Formic Acid Ethyl Alcohol Ethyl Formate Acetic Acid Ethyl Alcohol Ethyl Acetate Ester Formation Ester Formation FISCHER ESTERIFICATION - formation of esters by condensation of carboxylic acid and alcohol in an acidic medium Ester Formation CARBOXYLIC ACID ALCOHOL ESTER Formic Acid Ethyl Alcohol Ethyl Formate Acetic Acid Ethyl Alcohol Ethyl Acetate CARBOXYLIC ACID ALCOHOL ODOR Formic Acid Ethyl Alcohol Rum Acetic Acid Ethyl Alcohol Fruity Acetic Acid Isopentyl Alcohol Banana Acetic Acid Octyl Alcohol Orange Propionic Acid Ethyl Alcohol Pineapple Lucas Test - to differentiate and categorize primary, secondary and tertiary alcohols using lucas reagent - cannot be used for water insoluble alcohols (>3 carbon atoms) LUCAS REAGENT: solution of anhydrous zinc chloride in concentrated hydrochloric acid Lucas Test CARBOCATION - ion containing a positively charged carbon atom Lucas Test Oxidation of Alcohols using Acidic Potassium Dichromate set of operational rules for organic redox: 1. an organic oxidation is an oxidation that increases the number of C-O bonds and/or decreases the number of C-H bonds 2. an organic reduction is an reduction that decreases the number of C-O bonds and/or increases the number of C-H bonds Oxidation of Alcohols using Acidic Potassium Dichromate Oxidation - primary and secondary alcohols readily undergo oxidation in the presence of mild oxidizing agents oxidizing agents: - potassium permanganate - potassium dichromate - chromic acid Oxidation of Alcohols using Acidic Potassium Dichromate Oxidation of Alcohols using Acidic Potassium Dichromate Oxidation of Alcohols using Acidic Potassium Dichromate Oxidation of Alcohols using Acidic Potassium Dichromate Oxidation of Alcohols using Acidic Potassium Dichromate  UST General Santos Ketones and Aldehydes Classification Tests for Hydroxyl- and Carbonyl- containing Compounds 2,4-Dinitrophenylhydrazine Test - qualitative test used to identify carbonyl compounds (aldehydes and ketones) 2,4-Dinitrophenylhydrazine Test OXIDATION OF ALDEHYDES AND KETONES Oxidizing agents: oxygen in air, potassium dichromate, tollens’ test, benedict’s test OXIDATION OF ALDEHYDES AND KETONES ▪ Aldehydes readily undergo oxidation to carboxylic acids and ketones are resistant to oxidation. OXIDATION OF ALDEHYDES AND KETONES ▪ Aldehydes are also oxidized to carboxylic acids by a variety of oxidizing agents, including potassium dichromate. OXIDATION OF ALDEHYDES AND KETONES ▪ Aldehydes are oxidized to carboxylic acids by the oxygen in the air. OXIDATION OF ALDEHYDES AND KETONES ▪ Aldehydes are also oxidized to carboxylic acids by a variety of oxidizing agents, including potassium dichromate. OXIDATION OF ALDEHYDES AND KETONES ▪ For Ketones Tollens’ Silver Mirror Test ▪ Oxidation test that distinguishes aldehyde and ketone ▪ Tollens’ reagent uses silver(I) oxide (Ag 2O) in aqueous ammonium hydroxide (NH4OH). ▪ Only aldehydes react with Tollens’ reagent. ▪ Oxidation with Tollens reagent provides a distinct color change because the Ag+ reagent is converted to silver metal (Ag), which precipitates out of the reaction mixture as a silver mirror. Tollens’ Silver Mirror Test Carboxylic Acid + Silver Tollens’ Silver Mirror Test Sample Result Interpretation aldehyde POSITIVE With Reducing Property ketone NEGATIVE Without Reducing Property Iodoform Test - identify presence of methyl ketone or secondary alcohols adjacent to a methyl group Iodoform Test  UST General Santos Post Laboratory Discussion: Classification Tests for Hydroxyl- and Carbonyl-containing Compounds Inorganic and Organic Chemistry Laboratory References ❖ Bettelheim, F. A, W. H., Brown, M. K. Campbell, S. O. Farrell & O. Torres. (2021). Introduction to General, Organic and Biochemistry, 12th ed. Boston, MA, USA: Cengage Learning End of discussion Do you have any questions? PRAYER AFTER CLASS Grant me, O Lord my God, a mind to know you, a heart to seek you, wisdom to find you, conduct pleasing to you, faithful perseverance in waiting for you, and a hope of finally embracing you, Amen.