Polarity and Hydrogen Bonding in Organic Chemistry

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Discussion Overview

The discussion revolves around the chemical reaction between p-toluidine and hydrochloric acid, as well as the polarity of benzoic acid. Participants explore the nature of the reaction and the characteristics of the molecules involved, including their polar and non-polar attributes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Homework-related

Main Points Raised

  • Some participants inquire about the type of reaction that occurs between p-toluidine and hydrochloric acid, suggesting it may be an acid/base reaction due to the presence of an amine group.
  • There is a discussion about whether the reaction can be classified as an addition reaction, with some uncertainty expressed regarding the products of the reaction.
  • Participants note that benzoic acid is generally more polar than many organic substances but less polar than smaller alcohols, indicating a spectrum of polarity rather than a binary classification.
  • Some argue that the carboxyl group in benzoic acid contributes to its polarity, while the size of the benzene ring may reduce its overall polarity compared to smaller acids.
  • Questions arise about how to explain the dual nature of benzoic acid being both polar and non-polar, with participants seeking clarification on how to approach this in their responses.
  • There is mention of the electrostatic potential map as a tool to visualize the polarity of benzoic acid, although some participants express difficulty in finding this resource.

Areas of Agreement / Disagreement

Participants express varying degrees of understanding regarding the reaction between p-toluidine and hydrochloric acid, with no consensus on the exact nature of the reaction or the products formed. The discussion on the polarity of benzoic acid also remains unresolved, with multiple perspectives on how to classify it.

Contextual Notes

Participants highlight the complexity of classifying molecules as polar or non-polar, indicating that the overall polarity may differ from the polarity of individual parts of the molecule. There is also an acknowledgment that the size of the molecule can influence its polarity.

jnimagine
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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??
 
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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.
 


Ygggdrasil said:
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...
 


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


Ygggdrasil said:
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?
 


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.
 


Ygggdrasil said:
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...
 


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.
 


so is it CH3C6H4NH2 + HCl -> CH3C6H4NH3+Cl-??
 
  • #10


Yes. To make it more readable:

R-NH2 + H+ = R-NH3+
 
  • #11


Borek said:
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...
 
  • #12


jnimagine said:
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.
 
  • #13


Borek said:
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...
 
  • #14


Ygg have addressed this question 48 hours ago.
 
  • #15


yeah... but I'm still not clear on why it's both polar and nonpolar...
 
  • #16


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.
 
  • #17


naele said:
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?
 
  • #18


anyone??
help~~~ T.T
how do i explain the way benzoic acid is polar and nonpolar?
 
  • #19


jnimagine said:
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?
 
  • #20


jnimagine said:
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..
 

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