glycerin n

[apochronaut]

Will the refractive index of glycerin go up or down when sucrose is dissolved in it?

[Hobbyst46]

Tried searching literature data. The answer depends on several variables, such as temperature, solubility and solution properties.
Most handbook RI's are given for 20C.

Many RI data are given for sugars in water solutions, not for the pure sugar. I am not sure which RI is higher - pure glucose vs pure glycerol.
Moreover, sugars do not dissolve well in pure glycerol. They dissolve better, the more moist the glycerol. Yet water lowers the RI significantly.

For the posted question, The nearest something I found, in an article.from the year 1953, is that in almost dry (99.96%) glycerol, that contains 5.7% sucrose, the RI at 25C is 1.4796. At 15C it is 1.4700.

And that in slightly wetter glycerol (95% glycerol), that contains 14.3% glucose, the RI at 25C is 1.4711. At 15C it is 1.472.
The RI is a simple additive properties, provided that the two components (glycerol and glucose) do not mutually interact in mixture, I doubt that it is strictly correct.

So as a rough estimate I would assume that the change (plus or minus) is less than 0.01. Open to debate of course.

[Hobbyst46]

FWIW: I also found in an article from 1926 (nearly a centrury ago - wow...) that the RI of solid glucose hydrate is 1.52-1.56; so perhaps adding glucose to glycerol should enhance the RI, but again - the change would be very small, of the order of 0.01.

[apochronaut]

So that tells me I guess that glucose has a higher n than glycerin but glucose is impractical. Obviously, I am wondering how much sucrose ( 1.00/ lb.) it would take to get glycerin close to 1.52. Eighty percent sucrose in water is just over 1.5. I was hoping a lower percentage of sucrose in glycerin would sub for immersion oil.
Maybe that's how the study of fruit fly genetics got started.

[Hobbyst46]

Any particular advantage of sugar as additive ? I could think that it is available, cheap, stable, harmless, easy to weigh and mix - but it does not dissolve in glycerol sans water.
Unforetunately, high-RI substances are not as good as sugars in any of the above respects...
Cinnamon bark oil would increase the RI but probably impractical for other reasons.
Must think about other things, solids... nano materials I am afraid that the quest for high-RI friendly materials is still a great challenge - especially for substances that can be mixed with liquids.

[apochronaut]

Yes. It seems about 6% is possible so maybe 1.48 or 9 might be the limit for non aqueous glycerin?

[Hobbyst46]

Yes. It seems about 6% is possible so maybe 1.48 or 9 might be the limit for non aqueous glycerin?

I think so. 1.48. I estimate that EVEN IF glucose were 14% soluble in anhydrous glycerol the RI would be 1.48 at the most. A weighted average of the two RIs.
Note that glycerol is hygroscopic.

[apochronaut]

There is always waterglass = ph 12 , the same as household bleach!

[ericmaslim]

I also found in an article from 1926 (nearly a centrury ago - wow...) that the RI of solid glucose hydrate is 1.52-1.56snow rider 3d

[apochronaut]

I also found in an article from 1926 (nearly a centrury ago - wow...) that the RI of solid glucose hydrate is 1.52-1.56snow rider 3d

corn syrup. honey might be similar.