Phenol differs from salicylic acid by only one functional group.

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  Difficult to ensure position of new group when modifying

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  100% atom economy

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  Derivative of Salicylic acid with fewer side effects

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  Not soluble, so was first medicine sold as a tablet

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  Expensive and time consuming to develop new drugs

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  Patents prevent other firms from copying drugs for a period of time

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  Medicines often have alternative uses that are discovered later

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    Aspirin and heart disease