Question

using the IR, the 13C, and DEPT NMR spectra of your product determine the identity of your unknown ester from a C-4 or C-5 alcohol. the identity of the C-4 or C-5 alcohol also needs to be determined.

The following C-4 or C-5 alcohols will be used in this experiment:

1-butanol (n-butyl alcohol)

2-butanol (sec-butyl alcohol)

2-methyl-1-propanol (isobutyl alcohol)

3-methyl-1-butanol (isopentyl alcohol)

1-pentanol (n-pentyl alcohol)

2-pentanol

3-pentanol

cyclopentanol

Questions:

1. Why is the mixture extracted with aqueous sodium bicarbonate solution? Give an equation and explain its relevance.

2. Using your alcohol, determine which starting material is the limiting reagent in this procedure. Which reagent is used in excess?

3. Tertiary alcohols do not work well in the procedure outline for this experiment; they give a different product than you might expect. Explain this and draw the expected product from t-butyl alcohol.

4. Why is glacial acetic acid designated as “glacial”?

The general reaction for this experiment is: + ROH 4,809 HC POR + H0 H2SO4 + R-OH H3COH H3COR + H2O acetic acid alcohol ester

Answer 1

Hi there, the unknown identified as n-butylacetate

IR:

2957 & 2862 cm-1, strong, sp3 C-H stretch

1738 cm-1, strong, ester C=O stretch

1364 & 1467 cm-1, sp3 C-H bending

1231 cm-1, strong, ester C-O stretch

below 1000 cm-1 out of plane vibrations

DEPT-135:

3 -CH₂- groups present as we can clearly seen 3 negative (downward) peaks.

HNMR & CNMR:

HNMR CNMR Hac V CH3 H3C 2 Assign shift Assign shift (ppm) integration splitting Зн 2.0 4.0 1.6 singlet triplet pentet sextet triplet 50358 20.8 168 62.4 26.5 18.5 12.0

Hope this helped you!

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