[baseball07]

Hi everyone.  I have this salt silane which terminates in ---COO- Na+  and I would like it to terminate in ---COOH.  I was told that an acid wash would replace the Na+ with an H which would give me a carboxylic acid.  What is this sort of reaction called?  How strong does the HCl solution have to be forthe wash?  Would a .1M HCl work?  Thank you.

[Mitch]

.1M seems a bit strong, you could probably get away with something less concentrated than that. The only way to be sure is to setup a titration, but an acid workup is a common synthetic technique. I'm not sure if it has a proper noun name for this reaction aside from what we've called it here so far.

[baseball07]

Thanks Mitch.  That's what I figured, I think I am going to use .001M HCl.  My next question is when to do this wash and what to use to rinse it off in.  The deposition of this Silane proceeds as follows.

1.  Dip sample into solution of ethanol/silane for 2 minutes.
2.  Rinse free of excess materials by dipping in ethanol.
3.  Cure sample at 110C for 5-10 minutes. 

My questions are thefollowing:
1.  Do I want to apply the silane, cure the sample, then perform the acids wash?  Or do I deposit the silane, wash with acid then cure at the end? 
2.  How long in the HCl wash do I want to keep the sample.  Few seconds or few minutes?
3.  After dipping the sample in the HCl do I want to rinse with dH2O, or Ethanol since that is the solventI used to deposit the silane with.

Thanks!

[Mitch]

I'm not exactly sure what your experiments are, so everything has to be taken with that qualification.

1.) Assuming you wanted to make the carboxylic acid on the surface of your sample, I would do the steps you outlined in the first part of your question.
2.) Kinda as long as you would expect a surface of salt to dissolve in water. Somewhere between seconds and a few minutes.
3.) I can see how one would consider washing with ethanol to make sense, but it is a bit silly since this acid work-up is already considered the rinse.