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Topic: HMDS  (Read 9081 times)

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Offline moov

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HMDS
« on: July 20, 2010, 03:06:11 AM »
Hi,I need best condition to removal (wash) of HMDS From my reaction mixture.My moeity is heat sensitive.For extaction i need to use low boiling solvent.Plz give me a suggestion as early as possible.
Moovendan

Offline Doc Oc

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Re: HMDS
« Reply #1 on: July 20, 2010, 01:56:12 PM »
I'm assuming HMDS is hexamethyldisilazane (ie; you used NaHMDS or KHMDS as a base).

A couple of washes with 1M HCl should be enough to get that out of your reaction, as long as your product doesn't have free amines or is acid sensitive in any way.

Offline moov

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Re: HMDS
« Reply #2 on: July 22, 2010, 08:59:37 AM »
Yes you are correct. I used NaHMDS.Our moiety is acid sensitive as well as temperature sensitive also...,if any other options other than acid workup. Because of temperature our product degrated as starting material.
Moovendan

Offline Doc Oc

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Re: HMDS
« Reply #3 on: July 22, 2010, 11:17:03 AM »
How are you planning on purifying your product?  If you're doing a flash column the HMDS won't move much unless you're using a very polar solvent system.

Offline stewie griffin

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Re: HMDS
« Reply #4 on: July 23, 2010, 01:17:20 PM »
If you can't extract with acid due to issues with your desired substrate, you could try a wash with some saturated copper sulfate. The copper ions coordinate with the amine functionality and help remove it from the organic layer.

Offline manishbiyani

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Re: HMDS
« Reply #5 on: August 15, 2010, 01:26:19 AM »
Normally, the standard protocol to remove any sort of co-ordination produced by HMDS reagents are multiple wash with saturated NH4Cl. Please make sure the washing is rigorous are it does take time remove any sort of co-ordination due to Lithium.

Offline discodermolide

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Re: HMDS
« Reply #6 on: August 15, 2010, 02:10:37 AM »
Hi,I need best condition to removal (wash) of HMDS From my reaction mixture.My moeity is heat sensitive.For extaction i need to use low boiling solvent.Plz give me a suggestion as early as possible.

Add acetic acid and you will get the TMS ester and ammonia. then distill the ester under vacuum if necessary

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