Classification Tests for Carboxylic Acid and Derivatives

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Classification Tests for Carboxylic Acid and Derivatives
Mary Catherine Sarte, John Emmanuel Sy, Allurie Umel,Franklin Yap, Mary Christine YouIntroduction

Carboxylic acids derivatives are simply groupsof compounds that contain a carbonyl group butwith an electronegative atom attached to thecarbon. The difference in the structure leads to amajor change in reactivity. The reactions of thesegroups of compounds involve nucleophilicsubstitution. Although there are abundant kindsof carboxylic acid derivatives, the experimentonly focuses on the common ones: acid halides,acid anhydrides, esters and amides.Carboxylic acids and their derivatives areusually seen in industrial processes and mostbiological pathways. Esters can be seen as fatsand within the cell membrane. Esters are alsopresent in pleasant smelling liquids that areresponsible with the fragrant odor of fruits andflowers. Amides are also present in animalprotein and also in industrial products such asnylon. Acid chlorides and acid anhydrides areused in the synthesis of carboxylic derivatives.These are not usually found in nature because of its high reactivity property.One property of carboxylic acids is that theyare acidic. Because of these, carboxylic acids aremostly made to react with bases such as NaOH toyield a water soluble metal carboxylates.Carboxylic acids and their derivatives reactwith nucleophiles which yields a formation of alcohol. The initially formed intermediate productexpels one of its substituents which is originallybonded to the carbonyl carbon forming a newcarbonyl compound. The reaction is callednucleophilic acyl substitution reaction.The procedure for acyl halides, acid anhydrides,esters and amides is hydrolysis. Hydrolysis issimply the reaction with water to yield acarboxylic acid. Also for acetyl chloride isalcoholysis: Schotten-Bauman Reaction. It is thereaction with an alcohol to yield an ester. Thealcohol used here was ethanol. Again for acetylchloride and acetic anhydride, the reaction usedwas aminolysis: anilide formation. Aminolysis isthe reaction with ammonia or amine to yield anamide. In this case, aniline was the ammonia andanilide, an amide, was produced. Hydroxamicacis test was used for ethyl acetate andacetamide.Through this experiment, students are able tovisualize, through the different reactions, thenecleophilic acyl substitution reaction forcarboxylic acids and it derivatives. The differentclassification tests for such are also observed. Experimental

A.Hydrolysis of Acid Derivatives Acyl halides and Acid anhydrides 1 ml of water was placed in a test tube. 10drops of the sample, in this case acetyl chlorideand acetic anhydride, was added in a drop wisemanner. A warming effect was noted. The firstresulting mixture was divided into two portions.To the 1 st

, 1 ml of 2% AgNO3 was added.Precipitation was observed. To the secondmixture, 1 ml of saturated NaHCO3 was added.An evolution of gas was observed. Esters
2ml of 25% NaOH solution was added to 1 mlof ethyl acetate. The mouth of the test tube wascovered and the test tube was heated in a boilingwater bath for about 5 minutes. The mixture wasthen neutralized with 10% HCL solution. With awafting motion, the odor of the solution wasnoted. Amides

1ml of benzamide was treated with 5ml of 10%NaOH solution. The solution was then heated toboiling. While heating, the test for the reaction of gas evolution was done by holding a piece of moist red litmus paper over the heated test tube. B.Alcoholysis: Schotten-Baumann Reaction

A mixture of 10 drops of acetic acid, 1mlethanol and 5 drops of conc. was warmedover a water bath for 2 minutes. The odor of theester formed was noted. Abstract
Carboxylic acids are mainly organic compounds containing at least one carboxyl group. Its general formulais represented by the formula R-COOH. Its derivatives, on the other hand, is defined as organic compoundscontaining a carbonyl group with an electronegative atom (oxygen, nitrogen or halogen)...
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