[cogujada]

Hello, I wonder if you could help me please.
I'm making different sol-gel solutions. These are the solutions:

• Sol-Gel ZnO solution:
In this case I had zinc atetate dihydrate (sigma aldrich 99.999% trace metal basis) and I added 0.913 g to 20 mL of Methoxyethanol. It was stirred at 60 °C during 30 minutes. Then, 1 mL of ethanolamine (stabilizer) was added, and the solution was stirred during 90 minutes at 60 °C. After that, it was kept aging at room temperature during 24 hours, and then stirred at 60 °C during 3 hours (were the solvents vaporized and the sol gel was formed)

• Sol-Gel ZnO solution Doped with Indium
The procedure was the same as for the ZnO solution, but Indium Nitrate hydrate was added (4:100 In:Zn mole basis) at the same time ethanolamine was added.

If you could, please, put the reactions of one solutions, I could probably deduct the reactions for the other one.
It may seem I have not tried, but i'm chemical engeineer and I'm currently substituting a physical chemist, and I'm no where near his knowlegde in mechanisms, reactions, etc. I've tried to deduct myself the reactions, but I'm not going anywhere (I think).
What I've read is that probably the complex Zn₄O(CH₃COO)₆ will be formed, but I don't know what is the propper reaction. Also acetic anhydride will form, but I also don't know how...
Could someone help me please...
Thanks!

[Hunter2]

What I am missing is, that if a ZnO gel should be formed, that no addition of Hydroxide was down. So you have only the zink acetate in your gel. The ethanolamine is alcaline and keeps Zn in solution, but I think its to less to form the Oxide.

[cogujada]

And the methoxyethanol?

[Hunter2]

Methoxyethanol also called Methylglycolether is only solvent.

[cogujada]

Hmmm what I can confirm is that a gel was formed... I really don't know if there is OH missing.
What I can also confirm is that numerous autors have used this method to form a ZnO sol-gel

[cogujada]

Methoxyethanol also called Methylglycolether is only solvent.

I've been thinking, what do you think about this?

Zinc Acetate dihydrate hydrolizes:
Zn(CH₃COOH)₂ + H₂O  Zn(OH)₂ + 2CH₃COOH
Then, both methoxyethanol and monoethanolamine condensate
Then we have a transesterification reaction between methoxyethanol and monoethanolamine (which have condensed previously)
Finally, we have a reaction of the zinc hydroxide with the compounds formed in the previous stage (transesterification), forming ZnO in a organic sol-gel matrix. Because I heat the solution, that organic matrix progressively evaporates, leaving a more viscous gel.

Do I have any stage correct?

[Hunter2]

Zinc Acetate dihydrate hydrolizes:
Zn(CH3COOH)2 + H2O  Zn(OH)2 + 2CH3COOH]

Need alcaline environment.  Is  ethanolamin strong enough?

Then, both methoxyethanol and monoethanolamine condensate
Then we have a transesterification reaction between methoxyethanol and monoethanolamine (which have condensed previously)

Condensate to what and how? Which transesterification? There is no ester. Reaction with acetic acid needs water free environment. Sulfuric acid  as water Catcher and catalyst.

Finally, we have a reaction of the zinc hydroxide with the compounds formed in the previous stage (transesterification), forming ZnO in a organic sol-gel matrix. Because I heat the solution, that organic matrix progressively evaporates, leaving a more viscous gel.

What evaporate?  Glycol ether need 126 °C boiling temperature .

[cogujada]

Zinc Acetate dihydrate hydrolizes:
Zn(CH3COOH)2 + H2O  Zn(OH)2 + 2CH3COOH]

Need alcaline environment.  Is  ethanolamin strong enough?

Then, both methoxyethanol and monoethanolamine condensate
Then we have a transesterification reaction between methoxyethanol and monoethanolamine (which have condensed previously)

Condensate to what and how? Which transesterification? There is no ester. Reaction with acetic acid needs water free environment. Sulfuric acid  as water Catcher and catalyst.

Finally, we have a reaction of the zinc hydroxide with the compounds formed in the previous stage (transesterification), forming ZnO in a organic sol-gel matrix. Because I heat the solution, that organic matrix progressively evaporates, leaving a more viscous gel.

What evaporate?  Glycol ether need 126 °C boiling temperature .

Maybe it is strong enough. pH after 2 h of aging was about 10.

Ethanolamine condensates to amino ethoxy ethanol 2 [NH₂CH₂CH₂OCH₂CH₂OH]
Methoxyethanol condensates to MeOCH₂CH₂OCH₂CH₂OMe

Both then react? Don't know mate...

With reference to the evaporation, although water's boiling point is 100 °C, if you heat it till 70 °C it will evaporate partially at least.

[Hunter2]

Ethanolamine condensates to amino ethoxy ethanol 2 [NH2CH2CH2OCH2CH2OH]
Methoxyethanol condensates to MeOCH2CH2OCH2CH2OMe

Even this will not happen. To get an ether by condensation you need extremly conditions.

[cogujada]

Well then I have absolutely no idea about which reactions are taking place 

Thanks by the way mate! 

[Hunter2]

Me too, normaly it needs a polymer like polyethylenglycol, polyvinylpyrollidin, polyacrylic acid, etc.
Then something to get Zn2+ precipitate as hydroxide, Maybe the Ethanolamin is capable for it
But the others Methylglycol is only the solvent where the reaction takes place.