Ketamine (C13H16ClNO) Ketamine General Facts Molecular formular: C13H16ClNO Systematic name: 2-(2-chlorophenyl)-2-(methylamino)cyclohexan-1-one (IUPAC name) Alternatenames: a. In medical jargon: Ketaject, Ketanest, dl-Ketamine, Ketalar, CI 581 base, CLSTA 20, Ketolar b. In drug jargon: special K, green, jet, K, and super C Molar mass: 237.092042 g/mol Appearance: white powder, colorless liquid History and Discovery Initial genesis: finding a substitude for Morphin as a anaesthetic initially: Heroin, however too addicting temporary substitute: phencyclidine (PCP) Phencyclidine strong analgesic properties, hallucinogenic effects leading to an introduction in drug world as „angel dust“ 1962: Ketamine as drug with milder side-effects but similar structure 1964: experiments on paid prisoners, first suspicion on effects on psyche 1966: patent by Clarke-Davis 1970: officially in use proven as safe and very effective anaesthetic and painkiller for humans and animals effects strike quickly and does not cause depression or collapse of airways Used for casualties of traffic accidents or battlefield victims Historical usage: Vietnam war as anaesthetic however, still with psychic side effects Synthesis (following the mechanism developed by Calvin L. Stevens) Initial reagent: cyclopentyl Grignard Step 0: Producing cyclopentyl Grignard Reacting cyclopentyl bromide with magnesium in solvent (ether or THF) Best results: distill solvent from Grignard under vacuum and replace with hydrocarbon solvent (e.g. benzene) Step 1: processing to (o-chlorophenyl)-cyclopentyl ketone Adding o-chlorobenzonitrile to cyclopentyl Grignard in solvent, stirring for long period of time (typically three days) Hydrolyzing reaction with mixture containing crushed ice, ammonium chloride and some ammonium hydroxide Extraction with organic solvent gives (o-chlorophenyl)-cyclopentyl ketone Step 2: processing to alpha-bromo (o-chlorophenyl)-cyclopentyl ketone ketone processed with bromine in carbon tetrachloride at low temperature (typical T = 0°C), addition of bromine dropwise forming orange suspension Suspension washed in dilute aquerous solution of sodium bisufide and evaporated giving 1-bromocyclopentyl-(o-chlorophenyl)-ketone Note: bromoketone is unstable, immeadiate usage. Bromination carried out with N- Bromosuccinimide result higher yield (roughly 77%) Step 3: processing to 1-hydroxycyclopentyl-(o-chlorophenyl)-ketone-N-methylimine Dissolving bromoketone in liquid methylamine freebase (or benzene as possible solvent) After time lapse (1h): excess methylamine evaporated, residue dissolved in pentane and filtered evaporation of solvent yields 1-hydroxy-cyclopentyl-(o-chlorophenyl)-ketone N-methylimine Note: longer time span (4-5d) for evaporation of methylaminemay increase yield Step 4: processing to 2-Methylamino-2-(o-chlorophenyl)-cyclohexanone (Ketamine) Method: Thermal rearragement (qualitative yield after 30min in 180°C) N-methylimine dissolved in 15ml decalin, refluxed for 2.5h Evaporation of solvent under reduced temperature followed by extraction of residue with dilute hydrochloric acid Treatment with decolorizing charcoal (solution: acidic => basic) Recrystallization from pentane-ether Note - alternative to use of decalin: pressure bomb Properties of chemical structure Arylcyclohexylamine derivative racemic compound, in pharmaceutical preparation racemic more active enantiomere esketamine (S-Ketamine) available as Ketanest S, but Arketamine (R-Ketamine) never marketed for clinical use R-Ketamine S-Ketamine Optical rotation: varies between salt and free base form free base form: (S)-Ketamine dextrorotation (S)-(+)-ketamine hydrochloridesalt: levorotation(S)-(-)-ketamine Reason found in molecular level: different orientation of substituents: freebase: o-chlorophenyl equatorial, methylamino axial salt: o-chlorophenyl axial, methylamino equatorial Usage of ketamine a. Medical usage injectionin I.V. systems in hydrochloric form, direct input in bloodstream normally used as anesthectic in veterinary medicine for small mammals, sometimes used on humans on humans: limited use as anaesthetic due to side effects anesthetic for diagnostic and surgical procedures that do not require skeletal muscle relaxation (dose number increasing with length of precedure as dose last for short periods of time) b. Drug abuse Consumption in combination with other drugs (e.g. cocaine, ecstasy, alcohol) consumption typically by injection or snorting, smoking and as pill also possible In form of liquid: date rape drug since colorless and odorless Medical aspect – effects on body and mind a. General sideeffects Reduce or eliminate pain Bad hallucinations if used to escape unpleasant thoughts/emotions Disorientation, confusion Drowsiness, amnesia Nausea, may progress to vomiting Difficulty in movements, may progress to numbness and temporary unable to move Higher heart rate and blood pressure (in high doses) „K-Hole“: intense, unpleasant hallucinations (visual and auditory), derealization, detachment from reality b. Short-Term sideeffects Aprupt high, starting 2-5mins. if smoked/swallowed or 30s if injected, lasting for one hour Relaxation in full body Detachments from body (higher doses) Hallucinations c. Long-Term sideeffects Addiction Severe abdominal pain Kidney problems Sources: http://creationwiki.org/Ketamine#Synthesis http://www.lycaeum.org/rhodium/chemistry/pcp/ketamine.html https://pubchem.ncbi.nlm.nih.gov/compound/ketamine https://pubchem.ncbi.nlm.nih.gov/compound/ketamine#section=Drug-Warning http://www.rsc.org/chemistryworld/2014/02/ketamine-special-k-drugs-podcast http://drugabuse.com/library/the-effects-of-ketamine-use/ http://www.drugfreeworld.org/drugfacts/prescription/ketamine.html http://onlinelibrary.wiley.com/doi/10.1002/1615-9314(20021101)25:15/17%3C1155::AID-JSSC1155%3E3.0.CO;2-M/pdf .