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Credit
The action of thionyl chloride on the methylene ethers of catechol derivatives. Pt. II. Piperonyloin, piperil and hydropiperoin / by George Barger and Arthur James Ewins. Attribution 4.0 International (CC BY 4.0). Source: Wellcome Collection.
Provider
This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.