Org. Synth. 1946, 26, 95
Submitted by C. F. Koelsch
Checked by C. F. H. Allen and J. VanAllan.
One hundred grams (0.75 mole) of p-methylacetophenone1
is added to a mixture of 250 ml. (4 moles) of concentrated nitric acid
(sp. gr. 1.42) and 1 l. of water in a 3-l. flask, and the mixture is refluxed in a hood
for 4 hours. After the mixture has been cooled, the sticky, yellow solid is collected on a 14-cm. Büchner funnel
, pressed down well, and washed with 300 ml. of cold water.
The moist solid is mixed with 1 l. of water and 35 g. of sodium hydroxide in a 3-l. three-necked flask, fitted with a mechanical stirrer and a reflux condenser, and the stirred mixture is heated almost to its boiling point. Through the momentarily opened third neck of the flask is added, in portions of about 20 g., 300 g. (1.9 moles) of potassium permanganate, at such a rate that the boiling of the stirred mixture is maintained without external heating. After the addition has been completed, the mixture is refluxed for 2 hours; if any permanganate remains it is destroyed by the addition of 25 ml. of ethanol. The mixture is then filtered through a 14-cm. Büchner funnel, and the manganese dioxide is washed by removing it from the funnel, slurrying with 500 ml. of hot water (Note 1), and filtering.
The combined filtrates are heated nearly to boiling and acidified with a solution of 108 ml. of concentrated sulfuric acid (sp. gr. 1.84) in 400 ml. of water. After the mixture has been cooled to room temperature, the terephthalic acid is filtered and washed by stirring on the filter with three successive 100-ml. portions of cold water. The product is dried in an evaporating dish on a steam bath. The yield of terephthalic acid which sublimes at 300° or higher without melting is 105–109 g. (84–88%) (Note 2) and (Note 3).
This extraction yields 1–2 g. of the product.
The acid is analytically pure. There is no satisfactory solvent for the recrystallization of large amounts of terephthalic acid
. Small quantities may be recrystallized from acetic acid
, but the purity of a properly precipitated and washed sample is not thereby improved.
The high yields of ethyl ester obtainable from the product attest its purity. A mixture of 50 g. of terephthalic acid
, 500 ml. of absolute ethanol
, and 25 ml. of sulfuric acid
was boiled for 16 hours and then distilled to half its volume and poured into dilute aqueous sodium carbonate
. There was obtained 56.7 g.
of diethyl terephthalate
), and from the wash water there was recovered 4.6 g. of terephthalic acid
; these materials account for 93.3% of the original substance.
has been obtained from a great many p
-disubstituted derivatives of benzene
by oxidation with permanganate, chromic acid
, or nitric acid
. The following routes appear to have preparative value: from p-toluic acid
by oxidation with permanganate; from p-cymene
by oxidation with sodium dichromate
and sulfuric acid
or from p-chloro- or p-bromobenzoic acid
by heating at 250° with potassium and cuprous cyanides
and from p-dibromobenzene7
or p-iodobenzoic acid
, and carbon dioxide
. It has been obtained also by the air oxidation of p-xylene
in the presence of cobalt naphthenates.9
Oxidations of p-toluic acid
have been patented.
Chemical Abstracts Nomenclature (Collective Index Number);
p-chloro- or p-bromobenzoic acid
potassium and cuprous cyanides
sulfuric acid (7664-93-9)
acetic acid (64-19-7)
sodium hydroxide (1310-73-2)
nitric acid (7697-37-2)
potassium permanganate (7722-64-7)
sodium carbonate (497-19-8)
carbon dioxide (124-38-9)
chromic acid (7738-94-5)
sodium dichromate (7789-12-0)
manganese dioxide (1313-13-9)
Terephthalic acid (100-21-0)
diethyl terephthalate (636-09-9)
p-Toluic acid (99-94-5)
p-iodobenzoic acid (619-58-9)
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