Polarity and Hydrogen Bonding in Organic Chemistry

[jnimagine]

Organic Chemistry question!

How do you write a balanced chemical equation for the reaction that can occur between p-toluidine and hydrochloric acid?? and is benzoic acid a polar or non-polar molecule overall??

 

[Ygggdrasil]

How do you think p-toluidine will react with hydrochloric acid? What type of simple reaction will this be?

Polar/non-polar is not an either/or type of question. There are varying degrees of being polar and non-polar. Overall, benzoic acid lies more toward the polar side compared to most organic substances, but it is not as polar as things like short-chain alcohols and other compounds.

 

[jnimagine]

How do you think p-toluidine will react with hydrochloric acid? What type of simple reaction will this be?

Polar/non-polar is not an either/or type of question. There are varying degrees of being polar and non-polar. Overall, benzoic acid lies more toward the polar side compared to most organic substances, but it is not as polar as things like short-chain alcohols and other compounds.

is the reaction an addition reaction? I'm not sure actually... :(
and the question asks us to state wheter benzoic acid is polar or not and explain why...

 

[Ygggdrasil]

p-toluidine contains an amine group. How do amine groups react with acids?

 

[jnimagine]

p-toluidine contains an amine group. How do amine groups react with acids?

hmm.. don't they combine to make amino acids?? but what would the chemical equation look like?

 

[Ygggdrasil]

Amine groups are basic. Hence they will react in an acid/base reaction with HCl.

Amino acids are compounds that contain both an amine group and a carboxylic acid group.

 

[jnimagine]

Amine groups are basic. Hence they will react in an acid/base reaction with HCl.

Amino acids are compounds that contain both an amine group and a carboxylic acid group.

sorry I've never learned that reaction... I'm still not sure what the products would be...

 

[Borek]

Surely you know how ammonia reacts with acids? For example with hydrochloric acid, giving ammonium chloride? Same happens with amines, proton gets into free electron pair on the nitrogen atom.

This is not type of reaction you expect in organic chemistry, this more like general chemistry or even inorganic, that's why you can't catch it.

 

[jnimagine]

so is it CH3C6H4NH2 + HCl -> CH3C6H4NH3+Cl-??

 

[Borek]

Yes. To make it more readable:

R-NH₂ + H⁺ = R-NH₃⁺

 

[jnimagine]

Yes. To make it more readable:

R-NH₂ + H⁺ = R-NH₃⁺

if i write it this way, i don't need to balance the equation?! ... because it asked for a balanced chemical equation...

and also, is benzoic acid a polar or nonpolar molecule?? i know that a part of it is polar and a part of it is nonpolar but the question asked me to state whether it's polar or not and explain why...

 

[Borek]

if i write it this way, i don't need to balance the equation?! ... because it asked for a balanced chemical equation...

It is balanced. But you must either explicitely write what R stands for, or write full formula of moiety instead.

 

[jnimagine]

It is balanced. But you must either explicitely write what R stands for, or write full formula of moiety instead.

Ok i see..
but just one more question..
I still can't figure out whether to state that benzoic acid is polar or nonpolar...

 

[Borek]

Ygg have addressed this question 48 hours ago.

 

[jnimagine]

yeah... but I'm still not clear on why it's both polar and nonpolar...

 

[naele]

It's polar because of the carboxyl group, but it's not as polar as say formic acid or acetic acid because of the size of the benzene framework. Try and deduce the general dipole moment. Alternatively, go to your computer lab and look up the electrostatic potential map of benzoic acid to see what it looks like.

 

[jnimagine]

It's polar because of the carboxyl group, but it's not as polar as say formic acid or acetic acid because of the size of the benzene framework. Try and deduce the general dipole moment. Alternatively, go to your computer lab and look up the electrostatic potential map of benzoic acid to see what it looks like.

so the bigger they are, the less polar they are?
i couldn't find the electrostatic potential map... what does it show?
is it both polar and nonpolar or do i have to state one or the other?
Is the overall polarity different from parts of the molecule?

 

[jnimagine]

anyone??
help~~~ T.T
how do i explain the way benzoic acid is polar and nonpolar?

 

[TdotJace1]

How do you write a balanced chemical equation for the reaction that can occur between p-toluidine and hydrochloric acid?? and is benzoic acid a polar or non-polar molecule overall??

This is just a guess... But it seems that you are a chemistry student... wait my psychic senses are coming so me... You're a U of T student... You are currently enrolled in CHM138... You are doing the pre-lab questions to experiment #1... getting warmer?? Your lab is next week... am i right?

 

[TdotJace1]

so the bigger they are, the less polar they are?
i couldn't find the electrostatic potential map... what does it show?
is it both polar and nonpolar or do i have to state one or the other?
Is the overall polarity different from parts of the molecule?

You should know that the carboxyl group allows for hydrogen bonding... but if the size of the molecule is very large, the effect of the substituent is reduced since it is MORE nonpolar than polar.. every molecule is polar at some parts and non polar at others.. you just have to guess wether it's overall polarity is high or low..