Final Lab Report - Alcohols

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2ROH + (NH4)2Ce(NO3)6 → Ce(NO3)4(ROH)2 + 2NH4NO3 [red color]

Eq. 7

Table 3. Ceric Nitrate Test Alcohols

Observations

Initial Color

Final Color

Isopropyl Alcohol

Yellow

Red

Ethanol

Yellow

Red

Tert-Butyl

Yellow

Red

H2O

Yellow

Yellow

Moreover, the alcohol sample was also tested whether it exhibits a primary, secondary, or tertiary property through two different tests: Chromic Acid Test and Lucas Test. In the Chromic Acid Test, primary and secondary alcohols are tested. Chromic acid, which is a strong oxidizing agent is used. Theoretically, it has been said previously that any organic product with at least one hydrogen atom will be further oxidized. Knowing that a primary alcohol reacted to chromic acid will result to a carboxylic acid, while a secondary alcohol will result to a ketone, observations show that ethanol and chromic acid resulted from a clear color to a blue color in 7 seconds. Whereas, isopropyl alcohol and chromic acid resulted to the same reaction but in 10 seconds. This suggests that ethanol oxidized faster for a reason that the alcohol carbon is attached to less alkyl groups and that the oxidation reaction depends on the alkyl portions of the molecule due the presence of hydrogen. The phenol and tert-butyl however, did not show any color change because there are no hydrogens attached to the alcohol carbon. Recalling that a carbon is oxidized when it loses a hydrogen or gains a more electronegative atom. In the case of the phenol and tert-butyl, the alcohol bearing carbon does not have any hydrogens attached. Thus, having the resulted outcome (Refer to Table 4.1). Below are the equations for each:

Eq. 8 1O: –CH2OH+ H2Cr2O7 [orange] →[H2SO4] RCOH + Cr2(SO4)3 [blue-green] → RCOOH

Eq. 9 2O: –CHROH + H2Cr2O7 [orange] →[H2SO4] RCOH : Cr2(SO4)3 [blue-green]

Eq. 10 3O: –CR2OH + H2Cr2O7 [orange] →[H2SO4] no reaction, no color change

Alternatively, the Lucas Test examines primary to tertiary alcohols. An emulsion was formed since its reaction with the Lucas Reagent is based on the rate of formation of insoluble alkyl chloride. Ideally, a primary alcohol remains unreactive for several hours; a secondary alcohol reacts in 5-10 minutes, while a tertiary alcohol reacts rapidly to form a cloudy solution from the alkyl halide and water. This reaction is determined by the formation of the carbocation intermediate. An immediate reaction occurs for tertiary compounds because of the formation of relatively stable tertiary carbocation. Same implies for the secondary and primary. The lesser the stability of carbocation, the longer for it to react. (Brooklyn University, n.d.). From the data collected, there has been a positive result with ethanol having no reaction taking place and tert-butyl having the fastest reaction (Refer to Table 4.2)

Table 4. Distinguishing 1o and 2o Alcohols from 3o Alcohols

Table 4.1 Chromic Acid Test (1o and 2o)

Observations

1 (Ethanol)

> Initial Color: clear

> Final Color: Blue

> Time: 7 seconds

2 (Isopropyl)

>Initial Color: clear

>Final Color: blue

>Time: 10 seconds

3 (Tert-butyl)

> did not turn blue

4 (Phenol)

> did not turn blue

Table 4.2 Lucas Test (1o,2o, and 3o)

1 (Ethanol)

No appearance of cloudiness

2 (Isopropyl)

slightly cloudy in approximately 5 minutes

3 (Tert-butyl)

Cloudy white in a second

Phenols were also studied through testing its acidity, its reaction with bromine water, and its solubility with ferric chloride. In nature, phenols (pKa>=10) are more acidic than ethanol (pKa>=16-20), but less acidic than acetic acid, a carboxylic acid (pka>=4). This difference implies a possible separation of the compounds. Mixing phenol with a dilute base of sodium bicarbonate converts it to its alkali salt and can be separated from the organic phase (Hunt, n.d.). This is evident from the data collected in Table 5. Initially, the three compounds: phenol, acetic acid, and ethanol are acidic. When added NaHCO3, their acidity changed based on their reaction with sodium bicarbonate as the pH paper ionize with their organic state. Phenol and ethanol turned basic while acetic acid remains acidic (Refer to Table 5). This could be inferred that acetic acid is the most acidic among the three compounds while ethanol is the least acidic. The results obtained are backed up theoretically, as stated previously.

Table 5. Acidity of Phenols

Observations

Initial pH

After adding 1Ml NaHCO3

Final pH

1 (Phenol)

Acidic

Bubble formation occurred

Basic

2 (Acetic Acid)

Acidic

Bubble formation occrred

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