Why is 2-methyl-1-propanol more soluble in water than 1-butanol?

Answer 1

these chemicals are both aldehydes and have a carbonyl group (C=O). They cannot form hydrogen bonds with other aldehydes, but will form hydrogen bonds with water molecules. the (delta) + charge on one of the hydrogen atoms in the water molecule can be sufficiently attracted to the the lone pair of the oxygen on the carbonyl group for a hydrogen bond to form.

Dispersion forces (van der waals) and dipole dipole attractions also exist between the molecules of the ketones or aldehydes and water. Forming these attractions releases energy, which also provides the energy needed to separate the water molecules and aldehyde or ketone molecules from each other so that they can mix together. As chain length increases, the hydrocarbon tail prevents such attractions occuring.


as propanal is a three carbon molecule and methanal a one carbon molecule, methanal will dissolve more easily due to its shorter hydrocarbon chain length. :D

Answer 2

Yes! In this case, it comes down to polarity, "like dissolves like!" H20 is very polar. Draw out the dipoles on methanal. You will find that there is a huge dipole moment on methanal, depleting the carbonyl carbon of electron density. Conversely, draw out the dipoles on propanal. You will find that the charge, although not completely non-polar, is distributed more equally than methanal because of the two terminal carbons on either side of the carbonyl carbon, making the molecule as a whole less polar and therefore less soluble in water.

Answer 3

Propanone and propanal are soluble in water because they have polar functional groups. In propanone, the ketone functional group is polar. Water is also polar, and therefore will dissolve propanone. In propanal, the aldehyde functional group is polar.

Answer 4

it's not