Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Ethyl Alcohol (Ethanol)
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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 Ethyl Alcohol provides, in addition to common physical constants, a general description including typical appearance, applications, change in state (approximate), aqueous solubility, and density. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Color (APHA), Solubility in Water, Residue after Evaporation, Acetone, Isopropyl Alcohol, Titrable Acid, Titrable Base, Methanol, Substances Darkened by Sulfuric Acid, Substances Reducing Permanganate, and Ultraviolet Spectrophotometry.
CH3CH2OH
Formula Wt 46.07
CAS No. 64-17-5
Suitable for general use or in ultraviolet spectrophotometry. Product labeling shall designate the uses for which suitability is represented on the basis of meeting the relevant specifications and tests. The ultraviolet spectrophotometry specifications include all of the specifications for general use.
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . clear, colorless liquid Applications . . . . . . . . . . . . . . . . . . . . . . . . extraction medium; chromatography solvent; preparation of indicator solutions Change in state (approximate) . . . . . . . . . . . . boiling point, 78 °C Aqueous solubility . . . . . . . . . . . . . . . . . . . . miscible Density . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.81
SPECIFICATIONS General Use Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥95.0% CH3CH2OH Maximum Allowable Color (APHA) . . . . . . . . . . . . . . . . . . . . . . 10 Solubility in water . . . . . . . . . . . . . . . . . . . Passes test
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4135 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Residue after evaporation . . . . . . . . Acetone, isopropyl alcohol . . . . . . . Titrable acid . . . . . . . . . . . . . . . . Titrable base . . . . . . . . . . . . . . . . Methanol (CH3OH) . . . . . . . . . . . . . Substances darkened by sulfuric acid . Substances reducing permanganate . .
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. 0.001% . Passes test . 0.0005 meq/g . 0.0002 meq/g . 0.1% . Passes test . Passes test
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Absorbance (AU) . 0.01 . 0.05 . 0.15 . 0.25 . 0.40
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Specific Use Ultraviolet Spectrophotometry Wavelength (nm) 270–400 . . . . . . . . . . . . . . . . 240 . . . . . . . . . . . . . . . . . . . 230 . . . . . . . . . . . . . . . . . . . 220 . . . . . . . . . . . . . . . . . . . 210 . . . . . . . . . . . . . . . . . . .
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TESTS Assay Analyze the sample by gas chromatography using the general parameters cited in [Part 2: Chromatography; Recommended Procedures; Gas Chromatography]. The following specific conditions are also required. Column . . . . . . . . . . . . . . . . . . . . . . . . . . Type I, methyl silicone Detector . . . . . . . . . . . . . . . . . . . . . . . . . TCD Measure the area under all peaks, and calculate the ethyl alcohol content in area percent.
Color (APHA) [Part 2: Measurement of Physical Properties; Color (APHA); Procedure for Color (APHA)].
Solubility in Water Mix 15 mL with 45 mL of water, and allow to stand for 1 h. The mixture should be as clear as an equal volume of water.
Residue after Evaporation [Part 2: Gravimetric Methods; Residue after Evaporation]. Evaporate 100.0 g (124 mL) to dryness in a tared, preconditioned dish on a hot plate (~100 °C), and dry the residue at 105 °C for 30 min.
Acetone, Isopropyl Alcohol Dilute 1.0 mL with 1 mL of water. Add 1 mL of a saturated solution of disodium hydrogen phosphate and 3 mL of a saturated solution of potassium permanganate. Warm the mixture to between 45 and 50 °C, and allow to stand until the permanganate color is discharged. Add 3 mL of 10% sodium hydroxide reagent solution, and filter, without washing, through glass. Prepare a control containing 1.2 mL of water, 1 mL of the saturated solution of disodium hydrogen phosphate, 3 mL of the saturated solution of potassium permanganate, 3 mL of 10% sodium hydroxide reagent solution, and 0.8 mL of acetone
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4135 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
[(CH3)2CO] standard solution. To each solution, add 1 mL of 1% furfural solution (described below), and allow to stand for 10 min. To 1.0 mL of each solution, add 3 mL of hydrochloric acid. Any pink color produced in the solution of the sample should not exceed that in the control. (Limit about 0.001% acetone, 0.003% isopropyl alcohol.)
For the Determination of Acetone, Isopropyl Alcohol
F u r f u r a l S o l u t i o n , 1 % . Dissolve 1.0 g of furfural in 100 mL of reagent-grade ethyl alcohol.
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Titrable Acid Add 10 mL to 25 mL of water in a glass-stoppered flask, and add 0.15 mL of phenolphthalein indicator solution. Add 0.01 N sodium hydroxide until a slight pink color persists after shaking for 30 s. Add 25 mL of the sample, mix well, and titrate with 0.01 N sodium hydroxide until the pink color is restored. Not more than 1.0 mL of the sodium hydroxide solution should be required.
Titrable Base Dilute 25 mL with 25 mL of water, and add 0.15 mL of methyl red indicator solution. Not more than 0.40 mL of 0.01 N sulfuric acid should be required to produce a pink color.
Methanol Dilute 5 mL with water to 100 mL. To 1 mL of the solution add 0.2 mL of dilute phosphoric acid (1:9) and 0.25 mL of a 5% potassium permanganate reagent solution. Allow to stand for 15 min, add 0.3 mL of 10% sodium bisulfite solution, and shake until colorless. Add slowly 5 mL of ice-cold 80% sulfuric acid (3 volumes of acid added to 1 volume of water), keeping the mixture cool during the addition. Add 0.1 mL of 1% chromotropic acid reagent solution, mix, and digest on a hot plate (~100 °C) for 20 min. Any violet color should not exceed that produced by 0.04 mg of methanol in 1 mL of water treated in the same way as the 1 mL of the diluted sample.
Substances Darkened by Sulfuric Acid Cool 10 mL of sulfuric acid, contained in a small conical flask, to 10 °C. Add dropwise, with constant agitation, 10 mL of the sample, while keeping the temperature of the mixture below 20 °C. The resulting solution should have no more color than either of the two liquids before mixing.
Substances Reducing Permanganate Cool 20 mL to 15 °C, add 0.10 mL of 0.1 N potassium permanganate, and allow to stand at 15 °C for 5 min. The pink color should not be entirely discharged.
Ultraviolet Spectrophotometry Use the procedure in [Part 2: Chromatography; Recommended Procedures; LC Suitability; Procedure for Absorbance] to determine the absorbance.
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4135 ACS Reagent Chemicals, Part 4
