Reaction of benzene Watch

coconut64
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Attachment 609010609012609000Attachment 609010609012 for this question , my answer missed out a step compared to the actual answer.
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coconut64
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The answer shows that the first step should be reacting the molecules with NABH4 to form an alcohol then you oxidize it. Can you just reduce aldehyde to carboyxlic acid directly ? Thanjs
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Pigster
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I think you meant to oxidise the aldehyde to the carboxylic acid, but yes you can.

1/2 the aldehyde to the carboxylic acid, the other half to the alcohol. Esterify.
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Kallisto
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(Original post by coconut64)
The answer shows that the first step should be reacting the molecules with NABH4 to form an alcohol then you oxidize it. Can you just reduce aldehyde to carboyxlic acid directly ? Thanjs
Aldehyde is not reduced, but oxidise to carboxylic acid. The rest of the reactions, measured by your sketches, seem to be all-right. Can't find a mistake in your esterify. Don't know where a step is missing.
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coconut64
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(Original post by Kallisto)
Aldehyde is not reduced, but oxidise to carboxylic acid. The rest of the reactions, measured by your sketches, seem to be all-right. Can't find a mistake in your esterify. Don't know where a step is missing.
Name:  1483744871766-288108227.jpg
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Size:  395.0 KB the first step of this is what I haven't included. So I am unsure about my answer . Thanks
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Kallisto
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(Original post by coconut64)
Name:  1483744871766-288108227.jpg
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Size:  395.0 KB the first step of this is what I haven't included. So I am unsure about my answer . Thanks
Oh yeah, I see. You have not included the reaction step for Benzoic acid (C6H5CHO) in your sketch. Would say this step can be excluded, if benzoic acid is in existence as an educt.
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coconut64
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(Original post by Pigster)
I think you meant to oxidise the aldehyde to the carboxylic acid, but yes you can.

1/2 the aldehyde to the carboxylic acid, the other half to the alcohol. Esterify.
So my reactions steps are also valid?
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Pigster
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The image you posted are my (and your) steps.

Nowhere does it show to oxidise the alcohol to the carboxylic acid, the image shows the oxidation (using Cr2O72-/H+) of the aldehyde.
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coconut64
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(Original post by Pigster)
The image you posted are my (and your) steps.

Nowhere does it show to oxidise the alcohol to the carboxylic acid, the image shows the oxidation (using Cr2O72-/H+) of the aldehyde.
Ok. The actual image actually shows the aldehyde is being reduced to an alcohol by reacting with NaBH4. But what's the point of that if they are oxidising aldehyde to carboyxlic acid in STEP 2?
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Pigster
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To make an ester, you need an alcohol and a carboxylic acid.

An aldehyde can be both converted to an alcohol, by reduction AND to a carboxylic acid, by oxidation.
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coconut64
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(Original post by Pigster)
To make an ester, you need an alcohol and a carboxylic acid.

An aldehyde can be both converted to an alcohol, by reduction AND to a carboxylic acid, by oxidation.
Are you suggesting that the alcohol made in step 1 is used to react with the carboxylic acid in step 3 ?

But I thought since the alcohol is a reagent, you don't need to produce it in order to react it with the carboxylic acid...

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Pigster
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The image shows three steps.

Step 1, the reduction of benzaldehyde to phenylmethanol
Step 2, the oxidation of benzaldehyde to benzoic acid
Step 3, the esterification of phenylmethanol and benzoic acid to the ester.
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coconut64
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(Original post by Pigster)
The image shows three steps.

Step 1, the reduction of benzaldehyde to phenylmethanol
Step 2, the oxidation of benzaldehyde to benzoic acid
Step 3, the esterification of phenylmethanol and benzoic acid to the ester.
phenylmethanol needs to be produced because the question said you only have 1 organic compound to start with?

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Pigster
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(Original post by coconut64)
phenylmethanol needs to be produced because the question said you only have 1 organic compound to start with?
The Q doesn't say "you only have 1 organic compound to start with"

It says "starting with benzaldehyde, C6H5CHO, as the only organic compound."
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coconut64
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(Original post by Pigster)
The Q doesn't say "you only have 1 organic compound to start with"

It says "starting with benzaldehyde, C6H5CHO, as the only organic compound."
My question is will I lose marks if I didn't write down the reaction of aldehyde with NaBH4 to produce the alcohol. I get that the alcohol reacts with the acid but I am wondering if you don't show how the alcohol is made, is that still okay?

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Pigster
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I suspect that you'd lose two marks, one for the reagents and conditions for the conversion and one for the equation.
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