Aldehydes and Ketones PDF

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Laboratory Report of Aldehydes and Ketones that all CHEM 238 students are require to complete. ...

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Maggie Tran TA: Keturah Odoi Organic Chemistry 238-202 Aldehyde and Ketone: Results and Discussion Introduction: Chemists spend enormous amounts of time and effort to create reactions that occur typically in nature. Living organisms have specific protein structures to drive the synthesis of certain reactions to a desired product. For chemistS devote time and effort to try and create the same products synthetically and identify if the product is in fact the product desired. In this experiment reactions of aldehydes and ketones are used to identify the starting product and its derivative. Results: The sample assigned was vial 508-E. The sample was water soluble, when mixed in a test tube containing water. During the distillation, the boiling point range of the 1st fraction was observed to be 65.8oC and the principle fraction was boiled out from 66-68oC. From the observed principle fractions boiling point the choices were narrowed down to 2-Methylpropanol, Butanol, and 2-Butanone by a boiling point observation alone. All tests were performed and can be observed in figure 1. Figure 1.

Test

Control

Test on Sample 508-E

Meaning of Results

MP

2,4 DNP

2-butanone

No alternating pi bonds

165-167.9

Iodoform

2-butanone

Positive, appearance of a yelloworange precipitate Positive, appearance of a bright yellow precipitate

NONE

Schiff’s Tollens’

2-methyl-2propanol 2-butanone

Semicarbazone

NONE

Presence of a methyl group attached to carbonyl carbon The compound is an aldehyde The compound is an aldehyde Identify MP

Positive, immediate appearance of a wine-red color Positive, appearance of a silver coating on test tube Crystal created from test

NONE NONE ERROR

Referring to figure 1 the results from the tests on sample 508-E. The 2,4 DNP results were positive with a yellow-orange precipitate, indicates that this molecule does not have alternating pi bonds which mean its saturated with hydrogen molecules. The 2,4 DNP recrystallized product was obtained and its melting point was measured to be 165-167.9oC. Next the Iodoform test was run and created a positive result which yielded an bright yellow precipitate. The test indicates a methyl group is attached to the carbonyl carbon. The Tollens’s and Schiff’s tests are run to

identify if the compound is an aldehyde, both results came back positive to confirm that the compound is indeed a aldehyde, narrowing down our choices. Next to observe the IR results to identify which of the 2 possible aldehydes are the molecule in question. The IR spec of the results showed wavelengths at 3466.55 cm-1 which correlates to an –OH stretch, which could be possible traces of a impure molecule due to having to use the 1st fraction. A peak at 2971.06 cm-1 and 2877.77 cm-1 which correlates to a –C-H bond, proving the molecule is saturated with C-H. A peak at 2711.01 cm-1 which correlates to a C=O bond, proving the molecule is an aldehyde or ketone. A peak at 1468.46 cm-1 which correlates to –CH2 bond, and a peak at 1397.61 cm-1 which correlates to a –CH3 bond. A peak at 1073.02 cm-1 which correlates to a C-C bondS. All these traces point to the molecule2-Methylpropanol, when observing its IR spec data online. Error: This experiment the principle fraction was used up during the experiment and could not be used to perform all but the 2,4 DNP test. So it was advised to use the 1st fraction. Since the 1st fraction contains impurities, it could be hypothesized that the Iodoform was a false positive. Since the IR spec of the principal fraction was obtained the IR was used to determine that the compound in question could possibly be 2-Methylpropanol. Also acetone was used to clean certain glassware, which could lead to a false positive iodoform test. Conclusion: In conclusion, the use of qualitative organic tests could be used to identify a compound based on functional groups. Using the IR spec and closely examining the peaks and determining what each peak represents by using a reference table to determine a compounds functional groups. In this experiment classification tests are used to understand how to identify a ketone or aldehyde by simple reaction tests. In the case for sample 508-E it is proposed that the sample is 2Methylpropanol. Yet, due to the fact of having to use the 1st fraction instead of the normally used principle fraction, results to be slightly skewed in the qualitative tests performed....