formation of α-phenyl-α-ethylmalonic ester. finally a condensation reaction with urea gives phenobarbital. the second approach utilizes diethyl carbonate in the presence of a strong base to give α-phenylcyanoacetic ester. alkylation of this ester using ethyl bromide proceeds via a nitrile anion intermediate to give the α-phenyl-α-ethylcyanoacetic ester. this product is then further converted into the 4-iminoderivative upon condensation with urea. finally acidic hydrolysis of the resulting product gives phenobarbital. a new synthetic route based on diethyl 2-ethyl-2-phenylmalonate and urea has been described. regulation the level of regulation includes schedule iv non-narcotic (depressant) (acscn 2285) in the united states under the controlled substances act 1970—but along with a few other barbiturates and at least one benzodiazepine, and codeine, dionine, or dihydrocodeine at low concentrations, it also has exempt prescription and had at least one exempt otc combination drug now more tightly regulated for its ephedrine content. the phenobarbitone/phenobarbital exists in subtherapeutic doses which add up to an effective dose to counter the overstimulation and possible seizures from a deliberate overdose in ephedrine tablets for asthma, which are now regulated at the federal and state level as: a restricted otc medicine and/or watched precursor, uncontrolled but watched/restricted prescription drug & watched precursor, a schedule ii, iii, iv, or v prescription-only controlled substance & watched precursor, or a schedule v (which also has possible regulations at the county/parish, town, city, or district as well aside from the fact that the pharmacist can also choose not to sell it, and photo id and signing a register is required) exempt non-narcotic restricted/watched otc medicine. selected overdoses a mysterious woman, known as the isdal woman, was found dead in bergen, norway, on 29 november 1970. her death was caused by some combination of burns, phenobarbital, and carbon monoxide poisoning; many theories about her death have been posited, and it is believed that she may have been a spy. british veterinarian donald sinclair, better known as the character siegfried farnon in the "all creatures great and small" book series by james herriot, committed suicide at the age of 84 by injecting himself with an overdose of phenobarbital. activist abbie hoffman also committed suicide by consuming phenobarbital, combined with alcohol, on april 12, 1989; the residue of around 150 pills was found in his body at autopsy. thirty-nine members of the heaven's gate ufo cult committed mass suicide in march 1997 by drinking a lethal dose of phenobarbital and vodka "and then lay down to die" hoping to enter an alien spacecraft.