Question

What would cause a refractive index of a synthesized sample to be different than it's known value from the CRC Handbook, etc.

I synthesized cyclohexanone from cyclohexanol with bleach and acetic acid through simple distillation and separation, finally aspiration.

CRC Handbook says the refractive index of cyclohexanone is 1.450

Our sample, looks very exact in regards to IR spectrum, had a RI of 1.3551

What are some possibilities? Thanks!

Answer 1

Possibilities are

1. Purity of compound CRC uses 99.99% purest samples

2. Moisture absorbed by sample during measurement, better to run under nitrogen atmosphere (First flush with N2 gas)

3. May be there is unreactive cyclohexanol still present and also other bleach, acetic acid are also present in minute quantities.

4. Instrument may not be calibrated accurately, a small error will lead to a large deviation.

5. Avoid parallax effects, such as optic imperfections (especially lens must be clean).

Thank You!

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