Methylphenidate (Ritalin) synthesis

[cokemuffin]

So would the process be to put the ritalin hcl in NaOH solution, get the ritalin freebase and then just put that in ipa to get isopropylphenidate? I'd guess the hcl should be added after esterfication to not replace the OH from the carboxyl group with a Cl, but i'm not 100% sure about that.

 

[G.Patton]

Hello, sorry for a long reply. I haven't seen you question.
No, eterefication isn't work like you describe. You have to get Ritalinic acid sodium salt and then get ester with IPA in acidic condition.
It won't work like you told =) What is a reason for these manipulations? Actually, I'm not sure that reaction will be sucsess. Moreover, you'll loose part of your ritalin.

 

[TheNut22]

When syntheses involves cyanides, I go to my local hardware store pool-chem section and by Na DCCA, or TCCA. They will do the same reaction as more poisonous cyanide forms. I've made so many times phenylacetic acid from DLPA, and so on ..

 

[dupskoslonia]

Hey guys. I have ritalinic acid. What do I need to make metylphenidate and etylphenidate? I'm a complete newbie, could you please explain me step by step? Would be really grateful

 

[kotkata]

Is there a protocol or beginner's guide or recipe of some sort to convert ritalinic acid to methylphenidate?

To my understanding it's not rocket, but I'm a bit confused how to get methylphenidate from ritalinic acid.

 

[SmartResearcher]

Hello everybody! Replying for dupskoslonia, I add recipe for methylphenidate hydrochloride from dl-threo-ritalinic acid (which is easy avaliable in China, price for 1 kg is about 600-700$). I made dl-threo-methylphenidate hydrochloride a few times of this recipe and it's absolutely easy and perfect. 1 kg of methylphenidate hydrochloride, you can do in 20L single-neck flask (you don't need reactor).

125g (0.57 mol) of dl-threo-ritalinic acid added to reactor. Then added 256.7g (5 mol) of dimethyl carbonate and 27.5g methanol. Then at room temperature with mechanical stirrer (magnetic stirrer is not good to this operation) slowly added 762g of 96% or more of sulphuric acid (temperature <80oC). The jacket temperature was increased to 85oC (target internal temperature about 70oC). The reaction was stirred overnight (at least 16 hours) at a jacket temperature of 85oC.

The resulting mixture was then cooled to 15-20oC. To the resulting mixture was then added 250g of isopropyl acetate followed by addition of 18% NaOH (212.5g, 1.68 mol), while maintaining the temperature below at 30oC. Then, the mixture stirred for about 15 minutes. The layers were allowed to settle for about 20 minutes and the lower, caustic (aqueous) layer separated and discarded. To the organic layer was then added deionized water (187.5g) and the resulting mixture stirred for about 20 minutes. The layers were allowed to settle for about 20 minutes and the lower, water layer seperated and discarded. The organic layer, contain dl-threo-methylphenidate.

A second reactor was charged with the solution of 37% HCl (59g, 1.05 mol) and IPA (250g). The internal temperature of the solution was adjusted to 55oC. To this reactor was then added the organic layer containing dl-threo-methylphenidate, prepared in STEP1, via addition funnel over 90 minutes, while maintaining the temperature at 55oC. Then the mixture was cooled to 10-15oC and stirred for 30 minutes. The resulting suspension was filtered through a Buchnner funnel and the wet cake washed with IpOAc (125g). Achieved about 110-125g of dl-threo-methylphenidate hydrochloride (exactly the same isomer like in pharmacy).

 

[kotkata]

Awesome, thank you so much, @dupskoslonia!

Really appreciated!!

 

[untryrgos]

Hi, thank for your synthesis way.I follow your way and some difference appeared.when I make sure all acid disappear and finished first step,I found so much salt separation. Is it the Methylphenidate sulfate? The pH is about 1 to 2.

 

[HerrHaber]

Methyl esters are also easily obtained in presence of an amino group by the action of chlorotrimethylsilane in methanol with a much more friendly workup but then again the cost is probably bigger and I also think the yields (these need to be compared). Ethylphenidate and isopropylphenidate have a much greater recreational value (and longer lasting more potent effect) I can't help but wander about employing biocatalyisis with different alcohols and NOVOZYME should be the first choice, most enzymatic esterification and transesterifications are tried first with this extremophile (Candida Antarctica) enzyme that is secreted in the extracellular medium therefore easier to harvest. It is best if the enzyme is immobilised on solid material (often superparamagnetic nanoparticles of Fe3O4 functionalized on the surface with the enzyme linked via some organosilicon linker) as they can be filtered out and reused, magnetic are even easier to process. I would gladly experiment with this on a small scale for which 50g ritalinic acid would suffice and this is probably below the usual MOQ. I think naphtidates are also very interesting, but performing the entire synthesis may prove difficult.