CHE-005-LAS-9-Rationale PDF

ACTIVITY NO.9 CHEMICAL PROPERTIES OF ALDEHYDES AND KETONES RACEL TRANGIA-BACTOL, RPh, MPA, MMSc  Both aldehydes and ketones contain a carbonyl functional group. A carbonyl group is a carbon atom double-bonded to an oxygen atom. An aldehyde is a carbonyl- containing organic compound in...

ACTIVITY NO.9 CHEMICAL PROPERTIES OF ALDEHYDES AND KETONES RACEL TRANGIA-BACTOL, RPh, MPA, MMSc  Both aldehydes and ketones contain a carbonyl functional group. A carbonyl group is a carbon atom double-bonded to an oxygen atom. An aldehyde is a carbonyl- containing organic compound in which the carbonyl carbon atom has at least one hydrogen atom directly attached to it. A ketone is a carbonyl-containing organic compound in which the carbonyl carbon atom has two other carbon atoms directly attached to it A. Reaction with Alcoholic Sodium Bisulfite Solution. Benzaldehyde 3. Is Unknown Sample A an aldehyde or a ketone compound? Support your answer. The Unknown Sample A is a ketone compound since it does not react with alcoholic NaHSO3 solution, or it does not form a bisulfite addition product as aldehydes do. 4. Is Unknown Sample B an aldehyde or a ketone compound? Support your answer. The Unknown Sample B is an aldehyde compound since it reacts with alcoholic NaHSO3 solution by forming solid crystal or white precipitate as the bisulfite addition product in the reaction mixture. This reaction is commonly used as a qualitative test to distinguish aldehyde from other carbonyl compounds. 3. Is Unknown Sample A an aldehyde or a ketone compound? Support your answer. The Unknown Sample A is a ketone compound since it does not react with Tollen’s reagent, or it does not form a silver mirror or precipitate as aldehydes do. 4. Is Unknown Sample B an aldehyde or a ketone compound? Support your answer. The Unknown Sample B is an aldehyde compound since it reacts with Tollen’s reagent by forming a silver mirror or precipitate in the reaction mixture. This reaction is commonly known as the silver mirror test and is used to detect the presence of an aldehyde group. Acetone Formaldehyde 3. Is Unknown Sample A an aldehyde or a ketone compound? Support your answer. The Unknown Sample A is a ketone compound since it does not react with Tollen’s reagent, or it does not form a color change to brick red or brick-red precipitate in the reaction mixture as aldehydes do. 4. Is Unknown Sample B an aldehyde or a ketone compound? Support your answer. The Unknown Sample B is an aldehyde compound since it reacts with Benedict’s reagent by forming a brick-red precipitate or color in the reaction mixture. This reaction provides a qualitative test for the presence of an aldehyde functional group in the compound. 3. Is Unknown Sample A an aldehyde or a ketone compound? Support your answer. The Unknown Sample A is a ketone compound since it does not react with Schiff’s reagent, or it does not form a pink or red colored complex in the reaction mixture as aldehydes do. 4. Is Unknown Sample B an aldehyde or a ketone compound? Support your answer. The Unknown Sample B is an aldehyde compound since it reacts with Schiff’s reagent by forming a pink or red colored complex in the reaction mixture. This reaction provides a qualitative test for the presence of an aldehyde functional group in the compound. ACTIVITY QUESTIONS: 1. What are the components of the following reagents: a. Tollen’s reagent Silver nitrate (AgNO3) Ammonium hydroxide (NH4OH) Water (H2O) b. Benedict’s reagent Copper(II) sulfate (CuSO4) Sodium citrate (Na3C6H5O7) Sodium carbonate (Na2CO3) c. Schiff’s reagent Basic fuchsin (pararosaniline hydrochloride) Sulfurous acid (H2SO3) or sodium metabisulfite (Na2S2O5) Water (H2O) 2. What is Oxidation Reaction. Do alcoholic NaHSO3 solution, Tollen’s reagent, Benedict’s reagent, and Schiff’s reagent exhibit oxidation reactions? Elaborate your answer. Yes, alcoholic NaHSO3 solution, Tollen’s reagent, Benedict’s reagent, and Schiff’s reagent all exhibit oxidation reactions under certain conditions. Alcoholic NaHSO3 solution undergoes oxidation reactions with aldehydes. In these reactions, the aldehyde is oxidized, while the bisulfite ion (HSO3-) is reduced to form a bisulfite addition product.  Tollen’s reagent is used to test for the presence of aldehydes, which undergo oxidation to carboxylic acids in the presence of the reagent. This reaction involves the oxidation of the aldehyde functional group.  Benedict’s reagent also undergoes oxidation reactions with aldehydes. – The reagent is reduced during this reaction, leading to the formation of a colored precipitate of copper(I) oxide Schiff’s reagent (fuchsine sulfurous acid solution) forms colored complexes with aldehydes, resulting from the oxidation of the aldehyde functional group to form a Schiff base. 3. Why can aldehydes readily undergo oxidation reactions whereas ketones do not? What are the expected products of aldehyde oxidation? Aldehydes can readily undergo oxidation reactions because they possess a hydrogen atom directly bonded to the carbonyl carbon, which can be easily removed by an oxidizing agent. This makes the carbonyl carbon of aldehydes more susceptible to oxidation compared to ketones, which lack such a reactive hydrogen atom. In mild oxidation conditions, aldehydes are typically oxidized to form carboxylic acids. 4. Can aldehydes and ketones undergo reduction reactions? What are the expected products of these reactions? Yes, both aldehydes and ketones can undergo reduction reactions. Reduction of aldehydes and ketones typically involves the addition of hydrogen atoms to the carbonyl carbon, resulting in the formation of alcohols. For aldehydes, the expected product of reduction is a primary alcohol. The carbonyl group is reduced to a hydroxyl group (-OH) attached to a carbon atom, which is bonded to only one other carbon atom. For ketones, the expected product of reduction is a secondary alcohol. The carbonyl group is reduced to a hydroxyl group attached to a carbon atom, which is bonded to two other carbon atoms. Example: 5. Draw the structure of the organic product formed when each of the following aldehydes and ketones are subjected to oxidation or reduction. If no reaction occurs, write N.R. a. b. c. N.R. 6. Draw the structural formula of the organic product when each of the following aldehydes is oxidized to a carboxylic acid. a. Pentanal b. Formaldehyde c. 3,4- Dichlorohexanal