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### Topic: Deprotection of Carboxybenzyl using 10% Pd/C & 1atm Hydrogen  (Read 4136 times)

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#### Optimist

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##### Deprotection of Carboxybenzyl using 10% Pd/C & 1atm Hydrogen
« on: December 16, 2016, 06:12:28 AM »
How much amount of 10% Pd/C catalyst w.r.t substrate is required for the deprotection of Carboxybenzyl (Cbz) group under one atm hydrogen pressure. how can we calculate the amount of catalyst required during this reaction?
« Last Edit: December 16, 2016, 06:58:26 AM by Optimist »

#### rolnor

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##### Re: Deprotection of Carboxybenzyl using 10% Pd/C & 1atm Hydrogen
« Reply #1 on: December 16, 2016, 09:55:06 AM »
You can not calculate the amount, it depends on how fast reaction you want. I dont now how many % I use but a half teaspoon to ten grams, something like that?

#### wildfyr

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##### Re: Deprotection of Carboxybenzyl using 10% Pd/C & 1atm Hydrogen
« Reply #2 on: December 17, 2016, 05:15:13 PM »
teaspoons on an organic chemistry forum!

#### teiwaz

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##### Re: Deprotection of Carboxybenzyl using 10% Pd/C & 1atm Hydrogen
« Reply #3 on: December 17, 2016, 08:21:39 PM »
i use normally about 20 w%, if you have 20g of substrate you can use 4g catalysator and stirr it overnight. if you want to know the ideal relation of cat. amount and time, you have to do some test reactions.

#### Optimist

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##### Re: Deprotection of Carboxybenzyl using 10% Pd/C & 1atm Hydrogen
« Reply #4 on: December 18, 2016, 02:15:39 AM »
You can not calculate the amount, it depends on how fast reaction you want. I dont now how many % I use but a half teaspoon to ten grams, something like that?

I think half teaspoon is too much. Would you more precise about the amount, I think it's dangerous to use too much in a laboratory scale experiment.

#### Optimist

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##### Re: Deprotection of Carboxybenzyl using 10% Pd/C & 1atm Hydrogen
« Reply #5 on: December 18, 2016, 02:19:11 AM »
i use normally about 20 w%, if you have 20g of substrate you can use 4g catalysator and stirr it overnight. if you want to know the ideal relation of cat. amount and time, you have to do some test reactions.

Actually i conducted experiment using 100mg for 1g substrate and stirred it overnight but my yield decreased after purification step. May be there are some unknown impurities which having the same retention time in silica column which remained when i done deportection of carboxybenzyl group. I have methyl ester group in my compound.

#### Dan

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##### Re: Deprotection of Carboxybenzyl using 10% Pd/C & 1atm Hydrogen
« Reply #6 on: December 18, 2016, 11:19:59 AM »
How much amount of 10% Pd/C catalyst w.r.t substrate is required for the deprotection of Carboxybenzyl (Cbz) group under one atm hydrogen pressure. how can we calculate the amount of catalyst required during this reaction?

I tend to go for about 25 mg of 10% Pd/C per mmol substrate, about 2.5 mol%, and run the reaction overnight. I might reduce the loading on larger scale.
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