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Author: Subject: Molishch's test: experiment suggestions
teodor
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[*] posted on 21-8-2019 at 01:12
Molishch's test: experiment suggestions


I've got a bottle of 1-naphthol and want to get some practice with Molishch's test. I'd like to do several interesting experiments with increasing complexity. Have you any ideas what experiments are worth making?
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Ubya
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[*] posted on 21-8-2019 at 02:34


maybe an azo dye? beta naphthol is used for para red, i don't know if there's a dye that uses 1-naphthol, but why not?




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teodor
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[*] posted on 21-8-2019 at 03:05


Quote: Originally posted by Ubya  
maybe an azo dye? beta naphthol is used for para red, i don't know if there's a dye that uses 1-naphthol, but why not?


Well, it is quite different but actually I was also thinking about comparing with beta naphthol in the same kind of reactions.

Thank you for the idea with azo dyes.
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Boffis
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[*] posted on 21-8-2019 at 03:16


Sulphonate then nitrate to get either Martius yellow or Naphthol yellow dyes. Numerous published procedures available on line and in books.

Preparation of 1,2 an 1,4 naphthaquinones and numerous derivatives in one of the organic preparation books in the SM library (Fieser I think).

1-naphthol is the starting material for a bewilder range of naphthalene compounds. There is an entire book dedicated to these compounds and processes. As Ubya suggests an azo dye; there are many azo-dyes prepared from 1-naphthol and its sulphonic acids

Methylate to 1-methoxynaphthalene, an unusually high refractive index liquid for a non-halogen bearing organic compound.
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teodor
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[*] posted on 22-8-2019 at 02:34


Thank you Boffis. 1-methoxynaphthalene looks interesting for me due to the refractive index. But I need dimethyl sulfate for this, and the procedure I found for making dimethyl sulfate (http://www.prepchem.com/synthesis-of-dimethyl-sulfate/) requires a vacuum pump which I don't have yet. So, I will save it for later.

Azo dyes synthesis looks more simple, but it doesn't catches me (I don't know how the final product can be useful/interesting).

But my question was about usage of alpha naphthol in Molisch test. So, I am thinking about :

- which organic material I can test for presence/absence/presence of small amount of carbohydrates
- what I can do with carbohydrate to convert it to another class of compound not detectable by the test
- what I can do with carbohydrate to convert it to another class of compound still detectable by the test
- what I can do with some class of compound to convert it to carbohydrate and proof the result with the test
- compare test results with different carbohydrates/concentration/types of organic samples etc/

For examples, I know that some cookies can contain derivatives of cellulose to make it more solid (I think they put it in some muffins). But also it contains sugar. Can I proof the presence of (synthetic) cellulose derivative with the test but do something with a sugar and flour to not interfere?


[Edited on 22-8-2019 by teodor]
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teodor
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[*] posted on 22-8-2019 at 04:42


Here I found something interesting for myself.
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nezza
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[*] posted on 24-8-2019 at 13:25


1 naphthol does undergo azo coupling with many phenols, usually giving red dyes. A particular one if you have p-nitroaniline is the synthesis of Magneson II which is a purple colour and can be used as a test for Mg++ ion in solution.



If you're not part of the solution, you're part of the precipitate.
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teodor
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[*] posted on 27-8-2019 at 01:53


Thank you nezza, that is interesting, I will read more about Magneson II, especially how sensitive is Mg test.
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