Examples 1 and 2 copied from US patent 3,197,479 show a similar type of reaction.
EXAMPLE 1
3-(2-hydroxyethyl)indole
A 3-liter, stainless steel, rocker autoclave was charged with 117 grams of indole, 100 ml. of ethylene glycol, and 7.0 grams of potassium hydroxide. The autoclave was sealed and heated at 250 degrees C. for 19 hours while agitating the reaction mixture by rocking. The autoclave was then cooled, opened, and the contents were filtered to remove solids. The filtrate was evaporated under vacuum to a volume of about 400 ml. and then admixed with 1 liter of water. The aqueous mixture was extracted with ether. On vacuum distillation of the ether extract there were recovered 21 grams of 3-(2-hydroxyethyl)indole as a fraction boiling at 150-186 degrees C. at 1.0 mm Hg. A sample of the 3-(2-hydroxyethyl)indole, after recrystallization from toluene melted at 56-57 degrees C.
[The melting point of 3-(2-hydroxyethyl)indole was reported by Oddo and Camberi, Gazz. Chem. Ital., 69, 19 (1939) to be 57-58 degrees C.]
EXAMPLE 2
3-(2-hydroxylethyl)indole
Employing apparatus and procedures similar to those described in example 1, an autoclave was charged with 234 grams of indole, 1146 grams of ethylene glycol, 126.2 grams of hydrated barium hydroxide (Ba(OH)2.8H2O) and 128 milliliters of water. The autoclave was flushed with hydrogen, sealed and heated at 250 degrees C. for 19.5 hours. There were produced 225 grams of 3-(2-hydroxyethyl)indole which were recovered as a fraction boiling at 160 to 174 degrees C. at 1.0 mm Hg.
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Notice that example 2 includes the addition of water just as the Organic Synthesis article on indole-3-acetic acid. There's 18 examples in the patent using diols such as propylene glycol, butane diol, hexane diol, etc. Some include flushing with hydrogen. It says in the specification (column 4 lines 30-35) the following:
In addition, it has been found desirable, especially when a 3-(hydroxycarbyl)indole is the desired product, to conduct the reaction under a hydrogen atmosphere. The hydrogen pressure can vary from atmospheric pressure to 500 psig or more, with pressures of from 50 psig to 20 psig preferred.