Analysis of 1-Hexanol and Hexanal Properties in Organic Chemistry

This assignment provides a detailed comparison of 1-hexanol and hexanal, two organic compounds. It begins by defining each compound, including their chemical formulas and structural representations. The study then examines their physical properties, specifically melting and boiling points, high...Read More

Organic Chemistry 1
ESSENTIAL CHEMISTRY
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Organic Chemistry 2
1-hexanol is an organic compound which has the chemical formula C6H13OH (Gooch
2011). It is an alcohol which has the condensed structural formula CH3 (CH2)5OH (Gooch
2011). It is derived from hexane by substituting one of the hydrogen atoms with a hydroxyl
group (-OH). The structure of the alcohol is shown in the table below. The melting point of
ethanol ranges between -53 to -41 ℃ while the boiling point ranges between 155 to 159℃
(Gooch 2011). On the other hand, as an aldehyde, hexanal is a product of the termination
phase of the oxidation of fats (Hornback 2005). It is a straight-chain six-carbon compound
which has the following molecular formula, C6H12O (Hornback 2005). It corresponds to a
molecule of hexane whose one of the terminal methyl groups has been oxygenated by an
atom of oxygen forming an aldehyde (Hornback 2005). The structural formula of hexanal is
shown in the table below. Its boiling point is about 131 degree Celsius at standard
atmospheric pressure (Mackay, Shiu, Ma, & Lee 2006).
It is observed that, 1-hexanol has a higher boiling point compared to hexanal. The
molecular weight of an organic compound determines the melting and boiling points of the
compound. An organic compound with a higher molecular weight will have higher melting
and boiling points. The molecular weight of 1-hexanol is about 102.17 g/mol while that of
hexanal is approximately 100.16 g/mol (Mackay, Shiu, Ma, & Lee 2006). This explains why
the melting and boiling points of 1-hexanol are higher than those for hexanal.
Alcohol Structure Melting
point (℃)
Boiling
point (℃
) at 760
mm Hg
Molecular
Weight
(g/mol)
Functional
group
1-
hexanol
-44.6 157.0 102.17
Hexanal -56.0 131.0 100.16

Organic Chemistry 3
The melting and boiling points of organic compounds are also dependent on the type
of the functional group attached to the compound. For 1-hexanol, the functional group is
hydroxyl (-OH) while hexanal contains a carbonyl group (C=O) (Bettelheim, Brown,
Campbell, & Farrell 2009). A comparison of the boiling points for aldehydes and the
corresponding alcohols shows that the alcohol is more polar because of the present hydrogen
bond. Due to the absence of a hydroxyl group in hexanal, there are no intermolecular
hydrogen bonds. This explains why 1-hexanal has higher melting and boiling points
compared to hexanal. Unlike 1-hexanol, hexanal has a carbonyl group which is polar since
oxygen is more electronegative compared carbon forming a partially charged dipole
(Bettelheim, Brown, Campbell, & Farrell 2009).
The carbonyl group has polar covalent bonds, dipole dipole forces and London forces
compared to the alcohol which has a hydroxyl group with stronger forces including polar
covalent bonds, hydrogen bonds, London forces and dipole forces (Bettelheim, Brown,
Campbell, & Farrell 2009). As a result, the -OH group requires the highest level of energy to
break the bonds
In conclusion, differences in the functional groups of 1-hexanol and hexanal can
account for the differences in the melting and boiling points of the two organic compounds.
Besides, the difference in the molecular weight of the compounds further justifies the
difference in the melting and boiling points of the two compounds. The higher the molecular
weight, the greater the melting and the corresponding boiling points.
References

Organic Chemistry 4
Bettelheim, F., Brown, W., Campbell, M., & Farrell, S. (2009). Introduction to Organic and
Biochemistry. Boston, MA: Cengage Learning.
Gooch, J. W. (2011). Hexanol. Encyclopedic Dictionary of Polymers, 366-366.
doi:10.1007/978-1-4419-6247-8_5938
Hornback, J. M. (2005). Organic Chemistry. Boston, MA: Cengage Learning.
Mackay, D., Shiu, W., Ma, K., & Lee, S. C. (2006). Handbook of Physical-Chemical
Properties and Environmental Fate for Organic Chemicals, Second Edition. Boca
Raton, FL: CRC Press.