Mixing Boric Acid, Sodium Borate and alcohol

This is for a liquid detergent that I am developing - when I dissolve boric acid (doesn't fully dissolve though) and then mix it with dissolved sodium borate( also doesn't fully dissolve in water), settling occurs after sometime.
How do firstly dissolve these chemicals and how do I prevent the settling of these after sometime at room temperature?




Before you go further with boric acid and sodium borate, you should know the characteristic properties of them first. Boric acid has the molecular formula $\ce{H3BO3}$ and has a triangular planner structure: $\ce{B(OH)3}$ with the central boron having only six electrons (not fulfilling Octet rule and hence a Lewis acid). According to [this article](https://www.ema.europa.eu/en/documents/report/boric-acid-borate-used-excipients-report-published-support-questions-answers-boric-acid-borates-used_en.pdf):



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> Its physical appearance is white or almost white crystalline powder or can call it colorless. It is soluble in water and in ethanol (96 per cent), and freely soluble in boiling water to give acidic solution. For example, 3.3% aqueous solution of boric acid shows $\mathrm{pH}$ of $3.8$–$4.8$. Boric acid is also soluble in glycerol (85 per cent).
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Thus, for instance, you may use heat to dissolve boric acid well. Yet, you may need to know this: $\mathrm{p}K\_\mathrm{a}$ of boric acid is $8.92$–$9.24$ that is sensitive to temperature, ionic strength, and concentration (Ref.1). Accordingly,



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> The $\mathrm{p}K\_\mathrm{a}$ varies with concentration because of polymerization above $\pu{0.02 M}$. Boric acid reacts reversibly with alcohols, especially 1,2-diols including carbohydrates, with carboxylic acids, thiols, and amines. These esters/adducts, are also Lewis acids with lower $\mathrm{p}K\_\mathrm{a}$ values. Boric acid can stabilize some materials while catalyzing the degradation of others.
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Thus, the settling you experience must be due to the polymerization of boric acid solution:


[![Polymerization in boric acid](https://i.stack.imgur.com/vIJ8l.png)](https://i.stack.imgur.com/vIJ8l.png)


[![Polymerization in boric acid-2](https://i.stack.imgur.com/gGHlb.png)](https://i.stack.imgur.com/gGHlb.png)


Finally, boric acid and/or borate can easily undergoes esterification with alcohol functions (Ref.2). For example,


[![esterification with alcohol](https://i.stack.imgur.com/4p3BM.png)](https://i.stack.imgur.com/4p3BM.png)




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**References:**


1. Antonio Lopalco, Angela A. Lopedota, Valentino Laquintana, Nunzio Denora, Valentino J. Stella, "Boric Acid, a Lewis Acid With Unique and Unusual Properties: Formulation Implications," *Journal of Pharmaceutical Sciences* **2020**, *109(8)*, 2375-2386 (ODI: <https://doi.org/10.1016/j.xphs.2020.04.015>).
2. Supachok Tanpichai, Farin Phoothong, and Anyaporn Boonmahitthisud, "Superabsorbent cellulose-based hydrogels cross-liked with borax," *Scientific Reports* **2022**, *12*, 8920 (12 pages) (ODI: <https://doi.org/10.1038/s41598-022-12688-2>).


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