The story of the genesis of this hoax was one of Asimov's favourite personal anecdotes and he retold it a number of times in print. At the time, Asimov was engaged in doctoral research in chemistry and, as part of his experimental procedure, he needed to dissolve catechol in water. As he observed the crystals dissolve as soon as they hit the water's surface, it occurred to him that if catechol were any more soluble, then it would dissolve before it encountered the water.
By that time Asimov had been writing professionally for nine years and was shortly to face the challenge of writing up his research as a doctoral dissertation. He feared that experience writing readable prose for publication might have impaired his ability to write the prose typical of academic discourse and decided to practice with a spoof article (including fake citations) describing experiments on a compound, thiotimoline, that was so soluble that it dissolved in water up to 1.3 seconds before the water was added.
Asimov was uncertain as to whether the resulting work of fiction was publishable, but offered it to John W. Campbell, the editor of Astounding Science Fiction (his preferred publication outlet). Campbell was delighted with the piece and accepted it for publication, agreeing to Asimov's request that it appear under a pseudonym in deference to Asimov's concern that he might alienate potential doctoral examiners at Columbia University were he revealed as the author.
Some months later Asimov was shocked to see the piece appear under his own name. In later years Campbell insisted that this was an oversight, though Asimov maintained a suspicion that Campbell had acted deliberately out of greater wordliness, for, in Asimov's words 'The Columbia Chemistry Department proved far less stuffy than I had feared' and his examiners effectively delivered their favourable verdict on his dissertation by good-naturedly asking him a final question about thiotimoline.
In subsequent years Asimov wrote three sequels ("The Micropsychiatric Applications of Thiotimoline", "Thiotimoline and the Space Age" and "Thiotimoline to the Stars"), though only the first of these matched the hoax article format of the original. In one of these he expounded a putative rationale for thiotimoline's behaviour: namely that the chemical bonds in the compound's structural formula were so starved of space that some were forced into the time dimension.