How do you reason that the least polar to the most in an order?
Alkane>Alkene>ether>ester>aldehyde>ketone>alcohol> acid
Any good explanation
Do u mean "<" instead of >? Other than that in the case of alkanes there are only dispersion(weakest) forces between them. Also a pi bond is weaker than a sigma bond so there is some charge sepation across alkene double bond. rest of them just think about number of C-O bonds and geometry of the functional group. More the number of c-o bonds greater the charge separation. Be sure to draw the net dipole movement diagram like we do in gchem to figure out polararity. Remember dipole movement is a vector so if more electronegative atoms are present in more than one location it may be reduced or completely cancelled. The order seems to follow the BP order due to hydrogen bonding.!!!!
Thank you so much. But, how do you explain between ester and aldehyde. Ester has more O than aldehyde, but it says that ester is less acidic than aldehyde.
And ketone, alcohol and acid is also hard to understand.
Thank you so much. But, how do you explain between ester and aldehyde. Ester has more O than aldehyde, but it says that ester is less acidic than aldehyde.
And ketone, alcohol and acid is also hard to understand.
Remember that Aldehydes and ketones can tautomerize from keto to enol forms. Enol form has an OH group in it. Because of this, ketones/aldehydes have a higher boiling point due to potential H bonding in the enol form. Although in an equilibrium between keto/enol forms, the keto form is favored; there's an -OH character to them in one instance or another that allows them to better hold together compared to esters and ethers which don't have an H group to H-bond with.
Between ketones and alcohols --> Think of it this way. Alcohols are always in a state with the -OH group present (that's the definition of them.) Ketones/aldehydes favor the more keto form over the enol form so aren't in the form with the -OH group present (enol) all the time. Thus, alcohols have higher boiling points than them.
Now for carboxylic acids --> they can dimerize as well as H bond with each other because of that C=0 group and -OH group, which is why they have the highest bp out of all the types.
