revisionlad
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Hi, I'll attach the image. It's basically asking why 'methyl' group is preferred and given a higher preference than 'oxo- in a dicarboxylic acid- as the correct answer in the Textbook says it is 1. I don't understand how tho?
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charco
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(Original post by revisionlad)
Hi, I'll attach the image. It's basically asking why 'methyl' group is preferred and given a higher preference than 'oxo- in a dicarboxylic acid- as the correct answer in the Textbook says it is 1. I don't understand how tho?
I suggest that the ketone loses priority by being one of the prefixes to the root, in this case alphabetic order is used to prioritize.

http://www.acdlabs.com/iupac/nomencl...93/r93_317.htm
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revisionlad
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(Original post by charco)
I suggest that the ketone loses priority by being one of the prefixes to the root, in this case alphabetic order is used to prioritize.

http://www.acdlabs.com/iupac/nomencl...93/r93_317.htm
Hi, thank you. I understand how the ketone loses priority to the root as the carboxylic acid is higher preference. I also understand why alphabetically the methyl would be named first.

But what I don't understand is how on a dicarboxylic acid like this, the methyl gets a higher priority position (numerical) in comparison to the ketone.

We get qs like this on my exam and they give you these names to choose from as multiple choice purposefully to catch students out. That's why I'm being extra particular.
Thanks.
.
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charco
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(Original post by revisionlad)
Hi, thank you. I understand how the ketone loses priority to the root as the carboxylic acid is higher preference. I also understand why alphabetically the methyl would be named first.

But what I don't understand is how on a dicarboxylic acid like this, the methyl gets a higher priority position (numerical) in comparison to the ketone.

We get qs like this on my exam and they give you these names to choose from as multiple choice purposefully to catch students out. That's why I'm being extra particular.
Thanks.
.
Like I suggested.

Once the groups become prefixes the normal priority rules do not apply and it becomes alphabetical.
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revisionlad
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(Original post by charco)
Like I suggested.

Once the groups become prefixes the normal priority rules do not apply and it becomes alphabetical.
Oh right okay. So alphabetical order dictates numerical position in this occasion?
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