Solvents

Homepage, Shamash, Quest for Dicyanin, Cheap Science, Other Materials, Solvents

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Again, Solvents

The below narrative might still be true. Perhaps the problems I am having solving dicyanine A in ethyl alcohol is related to the manufacturer or condition of my sample, rather than the solvent.

For the moment, I am focusing on use of methyl alcohol and pinacyanol

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Solvents

How shall we dissolve the expensive, fragile, scarce, crucial organic dyes? Positively identifying Dr. Kilner's materials is vital.

Unfortunately, he only refers to his solvent as an "alcoholic solution." Bagnall also refers to the dye as being dissolved in "alcohol" (pg 49.) He also recommends triethsnolamine, a rather nasty substance; we probably won't end up using that.

However, the 1924 edition of the International Colour Index also only refers to "alcoholic solutions", so whatever was in use was ubiquitous. When was the isopropanol process invented?

Try cross referencing alcoholic solvents with alcoholic antiseptics. It makes sense that the alcohol solution that a doctor would have on hand would be an antiseptic.

Dr. Kilner and Mr. Bagnall only refer to the dye as being in an "alcoholic solution," so they apparently felt further distinction was unnecessary. The 1924 ICI similarly refers to "alcoholic solutions" of various compounds, but does not specify a particular kind of alcohol.

What kind of alcohol would Dr. Kilner have used in his practice? Common sense tells us that a physician's most familiar alcohol would be used for antiseptic purposes. If we cross-reference antiseptic alcohols with solvent alcohols, we are left with three candidates: ethanol, propanol, and isopropanol, all of which are in common use today.

But propanol and isopropanol were invented by Standard Oil. The process to produce them from oil refining by-products was published in 1922, after the death of Dr. Kilner, and came into common use sometime after that. That leaves an ethanol mixture as the most likely solvent.

Conclusion

The most likely solvent used by Dr. Kilner was surgical alcohol. For a physician of his time period, that would most likely have been ethanol mixed with water and possibly other denaturing ingredients. See the solvents page for the full story and supporting material.

Substituting Available Materials

Using commercial grade denatured alcohol as an initial solvent is not unreasonable, if USP grade ethanol / surgical alcohol is not available. I speculate that the lifetime of the dye solution may be shortened, rather than that the color will be drastically changed.

Antiseptic + Solvent Alcohols

• Alcohol Solvents
  • Solvent alcohols: 22 listed, relevant ones are probably Denatured Alcohol, Isopropyl Alcohol, Ethanol, Methanol
• Antiseptics
  • Antiseptic alcohols: Ethanol, Propanol, Isopropanol, or mixtures of these.
    • Note that Isopropanol creation process inherently leaves 1% - 30% water. Reaching 1% requires at least three processing steps.
  • Science.Technology.Society Surgical alcohol is commonly ethanol (60-90%), 1-propanol (60-70%) and 2-propanol/isopropanol (70-80%) or mixtures of these alcohols.

Likely Solvent Candidates

• Ethyl Alcohol
  • Ethyl Alcohol, Denatured from Sciencestuff
    • .90 Ethyl, .05 Isopropyl, .05 Methyl alcohols
  • Substitute Denatured alcohol from hardware store
    • Also use in alcohol lamps
    • Successfully obtained denatured alcohol from Home Depot painting department.
• Isopropyl alcohol
  • Isopropyl alcohol, 90% v/v from Sciencestuff
    • Solves nonpolar / lipophilic compounds readily.
    • Relatively non-toxic
    • Evaporates readily
  • Substitute common 91% variety from local drugstore
  • 70% might be better because of the need for the red component-- would Kilner have had 70% alcohol at his disposal?
  • aka Propyl alcohol
  • aka Propan-2-ol
    • Isopropyl alcohol is used as an antiseptic , which may mean Dr. Kilner would have used it in his office routinely as "alcohol".
  • Aha! Isopropyl and propyl alcohol were invented by Standard Oil Company. The process to manufacture them was published in 1922, after the death of Dr. Kilner.
    • A Handbook of the Petroleum Industry, Title Page
    • A Handbook of the Petroleum Industry, Petro-alcohol process, p399

Solvent Search Concluded

We can use Denatured Ethyl alcohol as the initial solvent with some confidence that it would have been available to Dr. Kilner, and commonly referred to as "alcohol." Denatured Ethyl alcohol is the actual definition of USP rubbing alcohol.