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Unformatted text preview: Mapua I nstitute of Technology Organic Chemistry Laboratory 2 Final Report Aldehydes and Ketones Von Joby M. Romero, K ristine S. Salvador School of Chemical Engineering and Chemistry, Mapua Institute of Technology, Intramuros, Manila, Philippines Experiment No. 4, Submitted on November 10, 2010 at N402 ABSTRACT Reaction behavior of aldehydes and ketones species was verified in this experiment. Acetaldehyde, acetone, benzaldehyde, acetophenone were subjected to different reaction reagents not only to test their chemical properties and reactivity but as well as to classify them. The tests applied are Benedicts test and Tollens test (for identifying aldehydes), condensation reaction and addition reaction (for the presence of carbonyl groups) and haloform reaction (for methyl ketones). I t is also compared in this experiment which of the tests with common function is more useful than the other. I t turned out that only acetaldehyde yields positive result with Benedicts reagent while on Tollents test, benzaldehyde also reacts, giving us an idea that it is better to use Tollens test in identifying aldehydes. For carbonyl group identification, both 2,4-DNP and NaHSO 3 reagents gives positive result upon reaction with acetaldehyde and acetone. Finally, presence of alkyl group is observed on both acetaldehyde and acetone because it gives positive outcome on Iodoform test. Keywords: classification test, carbonyl group, alkyl group, aldehydes, ketones 1 I N TRODUCT ION Aldehydes and ketones were another functional groups to be studied for this course. These functional groups are classified as a carbonyl group (carbon doubly bonded to oxygen) and are characterized to be useful. These functional groups are important in synthetic organic chemisty and also responsible for the pleasant odor of naturally occurring products. For this reason, aldehydes and ketones are normally utilized and extracted for perfumery or food flavoring purposes. The degree of substitution of the carbonyl carbon is one of the major differences between these two functional groups. For aldehydes, the carbonyl carbon posses one R (alkyl, aryl, etc.) group while the carbonyl carbon of ketones contains two R attached to it. This distinguishing difference is responsible for the variation in structure and properties of both carbonyl containing compounds. Figure . Structure of carbonyl groups aldehydes and ketones As to reactivity, carbon-oxygen double bond found on both groups is highly polarized due to the electronegativity difference of oxygen relative to carbon. Since carbon (also known as the beta carbon) is partially positive, it acts as electrophilic specie that is susceptible to nucleophilic attack. Reactions of aldehydes and ketones primarily occur in the carbonyl group particularly at the partially positive carbonyl carbon....
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