Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Isatin (2,3-Indolinedione)
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Part 4, Monographs for Reagent Chemicals: General Descriptions, Specifications, and Tests eISBN: 9780841230460 Tom Tyner Chair, ACS Committee on Analytical Reagents James Francis Secretary, ACS Committee on Analytical Reagents
ABSTRACT This monograph for Isatin provides, in addition to common physical constants, a general description including typical appearance, applications, change in state (approximate), and aqueous solubility. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Sensitivity to Thiophene, Melting Point, Alcohol-Insoluble Matter, and Residue after Ignition.
C8H5NO2
Formula Wt 147.13
CAS No. 91-56-5
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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orange solid reagent for cuprous ions, mercaptans, and thiopene melting point, 203 °C (partial sublimation) soluble in boiling water
SPECIFICATIONS Sensitivity to thiophene . . . . . . . . . . . . . . . . Passes test Melting point . . . . . . . . . . . . . . . . . . . . . . . 199–204 °C Maximum Allowable Alcohol-insoluble matter . . . . . . . . . . . . . . . . 0.01% Residue after ignition. . . . . . . . . . . . . . . . . . 0.05%
© 2017 American Chemical Society
A
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4178 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Sensitivity to Thiophene Add 5.0 mL of freshly prepared (sample) isatin solution (described below) to a dry, clean 50 mL porcelain crucible. Carefully overlay with 1.0 mL of thiophene standard solution (described below). Allow to stand undisturbed for 1 h, and compare with a blank containing 5.0 mL of isatin reagent solution and 1.0 mL of thiophene-free hexanes (described below) in a 50 mL porcelain crucible. A bluish-green color should develop as a halo or ring at the phase separation with the sample solution when compared to the blank.
For the Determination of Sensitivity to Thiophene
S o l u t i o n A . Dissolve 0.25 g of sample in 25 mL of sulfuric acid.
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S o l u t i o n B . Dissolve 0.25 g of ferric chloride in 1 mL of water. Dilute to 50 mL with sulfuric acid, and allow the evolution of gas to cease. I s a t i n S o l u t i o n . To 2.5 mL of solution A, add 5.0 mL of solution B, and dilute to 100 mL with sulfuric acid. T h i o p h e n e S t a n d a r d S o l u t i o n ( 0 . 0 0 1 m g o f C 4 H 4 S i n 1 m L ) . Transfer 1.0 g (0.95 mL) of thiophene to a 100 mL volumetric flask. Dilute to the mark with thiophene-free hexanes (described below), and mix. Transfer 1.0 mL of this solution to another 100 mL volumetric flask. Dilute to the mark with thiophene-free hexanes, and mix. Transfer 1.0 mL of this solution to a third 100 mL volumetric flask, dilute to the mark with thiophene-free hexanes, and mix. T h i o p h e n e - F r e e H e x a n e s . Add 350 mL of hexanes to a 500 mL separatory funnel, and add 50 mL of sulfuric acid. Shake, and allow the phases to separate. Extract the acid layer from the funnel. Add another 50 mL of sulfuric acid, and extract again. Discard the acid washings.
Melting Point [Part 2: Measurement of Physical Properties; Melting Point].
Alcohol-Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Dissolve 10.0 g in 250 mL of warm reagent alcohol. The solution should be orange-red. Do not digest the solution. Filter through a tared filtering crucible, wash well with warm reagent alcohol, and dry at 105 °C.
Residue after Ignition [Part 2: Gravimetric Methods; Residue after Ignition]. Gently ignite 2.0 g. Moisten the char with 1 mL of sulfuric acid.
© 2017 American Chemical Society
B
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4178 ACS Reagent Chemicals, Part 4
