CN103387562A - Preparation method of 3', 3'', 5', 5''-tetraiodophenolsulfonphthalein - Google Patents

Abstract

The invention relates to a preparation method of 3', 3'', 5', 5''-tetraiodophenolsulfonphthalein. The preparation method comprises the following steps: (1) adding iodine into a 40 wt% sodium hydroxide solution with stirring at 0-5 DEG C, after completely dissolving, adding a 10 wt% sodium hypochlorite solution, leaving to obtain a sodium hypoiodite solution; (2) dissolving phenol red in a sodium hydroxide solution, cooling to 5-10 DEG C, adding into the sodium hypoiodate solution little by little with stirring, after adding stirring for 10 min, heating and dissolving, adjusting the pH value to 5-6 with acetic acid, leaving for 30 min, then adding hydrochloric acid to adjust the pH value to 1-2, filtering out crystals and washing with hot dilute hydrochloric acid, and draining to obtain a crude product of 3', 3'', 5', 5''-tetraiodophenolsulfonphthalein; and (3) dissolving the crude product with a sodium hydroxide solution, filtering, neutralizing the filtrate with hydrochloric acid to obtain a pH value of 5-6, precipitating the precipitate, filtering, performing recrystallization, and performing air drying to obtain 3', 3'', 5', 5''-tetraiodophenolsulfonphthalein. By selecting a synthetic method of a water-soluble sodium salt, the preparation method is more universal and practicable, easily available in raw materials, short in period and simple to operate.

Description

The preparation method that a kind of tetraiodo is phenol red

Technical field

The invention belongs to the chemical reagent field, relate to a kind of indicator, the phenol red preparation method of especially a kind of tetraiodo.

Background technology:

Acid base indicator is often referred to a class material that is accompanied by colour-change along with the change of pH, is the indispensable chemical substance of chemistry and analysis field, and this tell-tale variation is actual is the result of a kind of " tautomer " structural changes.

This tautomer has the character of conjugate acid-base pair, is in each other a kind of equilibrium state.The pH value just can affect their balance while changing, and balance moves and be attended by the change of structure, the mutual conversion of acid or the alkali formula of proton occurred losing or obtaining, and namely we study the pH indicator to the indicator of this moment.

In actual applications, wish that usually the color change interval of indicator is narrower good, even pH value of solution has less variation also can make indicator produce sharp variation like this.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, provide a kind of tetraiodo phenol red preparation method, the present invention selects the synthetic method of water-soluble sodium salt, and more common easy row, raw material are easy to get, the cycle is short, easy and simple to handle.

The present invention solves its technical problem and takes following technical scheme to realize:

The preparation method that a kind of tetraiodo is phenol red, step is as follows:

⑴ in the 40wt% sodium hydroxide solution, then stir and to add iodine during with 0-5 ℃ down, after it dissolves fully, adds the 10wt% chlorine bleach liquor, and placement, obtain the hypoiodous acid sodium solution;

⑵ be dissolved in sodium hydroxide solution phenol red, be cooled to 5-10 ℃, join gradually in the hypoiodous acid sodium solution under stirring again, add rear stirring 10 minutes, heating for dissolving, be 5-6 with the vinegar acid for adjusting pH value, placed 30 minutes, then adding the salt acid for adjusting pH value is 1-2, filters out crystallization and with the dilute hydrochloric acid of heat, washs, be filtered dry, obtain the phenol red crude product of the tetraiodo;

⑶ crude product dissolves with sodium hydroxide solution, and after filtering gained filtrate being neutralized to the pH value with hydrochloric acid is 5-6, separates out precipitation, and filtering-depositing will precipitate and use ethyl alcohol recrystallization, dries to such an extent that the tetraiodo is phenol red.

And described 40% sodium hydroxide solution: iodine: 10% clorox: phenol red weight ratio is 6:7.2:21:5.

Advantage of the present invention and beneficial effect are:

1, the tetraiodo-benzene phenol red (C19H1OI4O5Smol857.97) of the present invention's preparation is water insoluble, is dissolved in ethanol, sodium hydroxide solution, and pH value 3.0-4.8 colors are by Huang Zhilan, mainly as acid base indicator, chromatographic analysis reagent.

2, the present invention selects the synthetic method of water-soluble sodium salt, and more common easy row, raw material are easy to get, the cycle is short, easy and simple to handle.

Embodiment

Be further described below in conjunction with embodiment, following examples are descriptive, are not determinate, can not limit protection scope of the present invention with this.

Per-cent with lower volume is mass percent

The preparation method that a kind of tetraiodo is phenol red, step is as follows:

⑴ in the 6kg40% sodium hydroxide solution, then stir and to add 7.2kg iodine during with 0-5 ℃ down, after it dissolves fully, adds the 21kg10% chlorine bleach liquor, and placement, obtain the hypoiodous acid sodium solution;

⑵ be dissolved in the 5L10% sodium hydroxide solution 5kg is phenol red, be cooled to 5-10 ℃, join gradually in the hypoiodous acid sodium solution under stirring again, add rear stirring 10 minutes, heating for dissolving, be 5-6 with the vinegar acid for adjusting pH value, placed 30 minutes, then adding the salt acid for adjusting pH value is 1-2, filters out crystallization and with the dilute hydrochloric acid of heat, washs, be filtered dry, obtain crude product;

⑶ crude product dissolves with the 6kg10% sodium hydroxide solution, and after filtering gained filtrate being neutralized to the pH value with hydrochloric acid is 5-6, separates out precipitation, and filtering-depositing will precipitate and use ethyl alcohol recrystallization, dry to obtain finished product.

Claims (2)

1. preparation method that the tetraiodo is phenol red, it is characterized in that: step is as follows:

⑴ in the 40wt% sodium hydroxide solution, then stir and to add iodine during with 0-5 ℃ down, after it dissolves fully, adds the 10wt% chlorine bleach liquor, and placement, obtain the hypoiodous acid sodium solution;

⑵ be dissolved in sodium hydroxide solution phenol red, be cooled to 5-10 ℃, join gradually in the hypoiodous acid sodium solution under stirring again, add rear stirring 10 minutes, heating for dissolving, be 5-6 with the vinegar acid for adjusting pH value, placed 30 minutes, then adding the salt acid for adjusting pH value is 1-2, filters out crystallization and with the dilute hydrochloric acid of heat, washs, be filtered dry, obtain the phenol red crude product of the tetraiodo;

⑶ crude product dissolves with sodium hydroxide solution, and after filtering gained filtrate being neutralized to the pH value with hydrochloric acid is 5-6, separates out precipitation, and filtering-depositing will precipitate and use ethyl alcohol recrystallization, dries to such an extent that the tetraiodo is phenol red.

2. the phenol red preparation method of the tetraiodo according to claim 1, it is characterized in that: described 40% sodium hydroxide solution: iodine: 10% clorox: phenol red weight ratio is 6:7.2:21:5.