Esters- Structual Formula and Other Problems (1 Viewer)

[Stopsign]

These questions have to be answered.
1. In esterification, where do both the H and -OH each come from when they form water?
2. What is the structual formula?
3. What is its 'homologous series' formula?
4. How do you name an ester?

Thanks for all those who help. It's my fault for not studying hard enough.

 

[Dreamerish*~]

1. In esterification, where do both the H and -OH each come from when they form water?

The H⁺ comes from the -COOH (carboxylic) group of the alkanoic acid, and the OH^- is simply the -OH (hydroxy) group of the alkanol.

2. What is the structual formula?

R₁-COO-R₂, where R₁ and R₂ are alkyl groups originating from the alkanoic acid and alkanol, respectively.

3. What is its 'homologous series' formula?

There isn't one, because esters can be made from any combination of alkanoic acids and alkanols, varying in length of carbon chain. However, the general formula for alkanols is C_nH_2n+2O or C_nH_2n+1OH; and the general formula for alkanoic acids is C_nH_2nO₂ with n > 0 or C_nH_2n+1COOH with n > 0.

4. How do you name an ester?

The "general formula" for the name of an ester is an alkyl alkanoate. The "-yl" part comes from the alkanol, and is formed by detaching the "-anol" part of an alkanol and replacing it with "-yl". For example, "methanol" becomes "methyl", and "butanol" becomes "butyl". The "-anoate" part comes from the alkanoic acid, and is formed by detaching the "-anoic acid", replacing it with "-anoate". For example, "methanoic acid" becomes "methanoate", and "butanoic acid "becomes "butanoate".

So if an ester is made from say, pentanol and methanoic acid, it would be called pentyl methanoate.

 

[Stopsign]

Thankyou Dreamerish. Problem solved.

You forgot to mention about the =0 (Oxygen's double bond).

 

[Dreamerish*~]

You forgot to mention about the =0 (Oxygen's double bond).

The -COOH (carboxylic acid group) implies the -C=O bond.

 

[wah]

The H⁺ comes from the -COOH (carboxylic) group of the alkanoic acid, and the OH^- is simply the -OH (hydroxy) group of the alkanol.

This is not correct. The OH- actually comes from the -COOH bond, while the H+ originates from the -OH bond. This can be found in the Surfing Text for the Acidic Environment.

 

[Dreamerish*~]

This is not correct. The OH- actually comes from the -COOH bond, while the H+ originates from the -OH bond. This can be found in the Surfing Text for the Acidic Environment.

I suppose that depends on from which source the information is obtained.

In the equation of the reaction which is:

CH₃-COOH + HO-CH₂-CH₃ → CH₃-COO-CH₂-CH₃ (Conquering Chemistry)

It's not clear whether the hydroxy group is detached from the alkanoic acid or the alkanol.

EDIT: Actually, I wouldn't be surprised if it varied. The -OH could come from either reactant because the reaction that takes place is a condensation reaction in which the functional groups are identical. It wouldn't make a difference (chemically) in the ester whether the OH group came from the alkanoic acid or the alkanol.

 

[Stopsign]

RCOOHR' is the form right?

R is the alkanoic acid.
R' is the alkanol. (That's attached to the oxygen).

Am I right?

 

[Dreamerish*~]

RCOOHR' is the form right?

R is the alkanoic acid.
R' is the alkanol. (That's attached to the oxygen).

Am I right?

R₁-COO-R₂, where R₁ was the alkanoic acid and R₂ was the alkanol.

There's no hydrogen atom. Both hydrogen atoms from the two OH groups were consumed in producing water.

 

[wah]

I suppose that depends on from which source the information is obtained.

In the equation of the reaction which is:

CH₃-COOH + HO-CH₂-CH₃ → CH₃-COO-CH₂-CH₃ (Conquering Chemistry)

It's not clear whether the hydroxy group is detached from the alkanoic acid or the alkanol.

EDIT: Actually, I wouldn't be surprised if it varied. The -OH could come from either reactant because the reaction that takes place is a condensation reaction in which the functional groups are identical. It wouldn't make a difference (chemically) in the ester whether the OH group came from the alkanoic acid or the alkanol.

Yeah, Conquering Chemistry doesn't explain which comes from which. But Surfing clearly illustrates this in the Ester chapter
That's why it's always wise to refer to several textbooks when you do your study
Though this -OH and H+ matter isn't really worth its controversy. I highly doubt you will be asked something so detail in any assessment task or the HSC.

 

[babywwq]

hey man
read the text book
good way is not waste time here