2-Chlorophenyl cyclopentyl ketone


2Chlorophenyl cyclopentyl ketone is used as a reagent in the preparation of bicyclic and polycyclic aromatic hydrocarbons. It acts as a pharmaceutical intermediate and also as an intermediate of ketamine.




What is 2-Chlorophenyl cyclopentyl ketone?

2Chlorophenyl cyclopentyl ketone is used as a reagent in the preparation of bicyclic and polycyclic aromatic hydrocarbons. It acts as a pharmaceutical intermediate and also as an intermediate of ketamine.

Chemical Name: 2-Chlorophenyl Cyclopentyl Ketone
Synonyms: (2-Chlorobenzoyl)cyclopentane; Cyclopentyl 2-Chlorophenyl Ketone; Cyclopentyl o-Chlorophenyl Ketone; (2-Chlorophenyl)cyclopentylmethanone;
CAS Number: 6740-85-8
Molecular Formula: C₁₂H₁₃ClO
Appearance: Clear Pale Yellow Oil
Melting Point: N/A
Molecular Weight: 208.68
Storage: Refrigerator
Solubility: Chloroform (Slightly), Ethyl Acetate (Slightly), Methanol (Slightly)

Category: Aromatics, Pharmaceuticals, Intermediates & Fine Chemicals,

Applications: 2-Chlorophenyl Cyclopentyl Ketone is used as a reagent in the preparation of bicyclic and polycyclic aromatic hydrocarbons. 2-Chlorophenyl cyclopentyl ketone

Step 1: Peroxyacid oxidation (requires isomerization of safrole) or Wacker oxidation (an elegant catalytic oxidation) produces the ketone “PMK” (piperonyl methyl ketone, also known as 3,4-MDP2P, or 3,4-methylenedioxyphenyl-2-propanone.) There are a lot of oxidization reactions available, but in this case we of course want something that will produce the Markovnikov product, with addition occurring at the more substituted end of the alkene. 2-Chlorophenyl cyclopentyl ketone

An initial oxidation to an alcohol followed by a second oxidation step to a ketone is also a possibility. Since safrole and PMK are carefully watched and regulated precursors, the current favorite precursor (typically bought from Chinese chemical manufacturers) is PMK glycidate.

PMK glycidate can reportededly be easily broken down into PMK simply by refluxing it with hydrochloric acid. (But read on about the chemical watch lists!)

Step 2: Reversible imine formation (occurs spontaneously when the ketone is placed in solution with methylamine freebase (not the hydrochloride salt.), 2-Chlorophenyl cyclopentyl ketone

Step 3: Reduction (via hydrides, aluminum-mercury amalgams, or electrical cells) or catalytic hydrogenation permanently converts the imine to MDMA. 2-Chlorophenyl cyclopentyl ketone

Since ketones and imines lack a chiral center, they (like a good Buddhist monk) do not project personal desires on the world, so the resulting product is racemic, containing a 50-50 mix of both the stronger S(+) isomer (which releases plenty of serotonin, dopamine and norepinephrine) and the weaker R(-) isomer (which is effectively just a serotonin releaser.) All MDMA sold on the streets appears to be racemic. 2-Chlorophenyl cyclopentyl ketone

A product containing only one isomer would not subjectively feel the way racemic MDMA does, being either more amphetamine-like or more sedating and mellow (like MDEA, which seems to be primarily a serotonin releaser.) Safrole is found in various “essential oils”, the most famous of which is sassafras oil, which can contain as much as 90% safrole. 2-Chlorophenyl cyclopentyl ketone

Since safrole (and isosafrole, MDP2P/PMK, and sassafrass oil) are “listed precursors” in the US they’re very hard to find. (Many remaining ‘sassafras oil’ products are now safrole-free in order to avoid regulation.) Even attempting to order one of these chemicals can bring law enforcement attention. 2-Chlorophenyl cyclopentyl ketone

The most famous route is probably one of Shulgin’s original synths from PIHKAL (third paragraph), starting with PMK (MDP2P) made from isosafrole. Isomerization of safrole is reportedly an easy operation, as described in the famous Strike synthesis collection. (A more compact review can be found in this old doc saved from Rhodium.), 2-Chlorophenyl cyclopentyl ketone

Shulgin’s ingenious use of aluminum foil and mercury as a reducing agent opened up a lot of possibilities for hobbyist-scale clandestine labs, but it comes with one ugly downside: Highly toxic mercury compounds. 2-Chlorophenyl cyclopentyl ketone

The disposal of the leftover chemical waste from clan-labs has always been an environmental and public health problem, with irresponsible chemists dumping waste in ditches or even flushing it down the drain into sewer systems. 2-Chlorophenyl cyclopentyl ketone

Mercury-aluminum amalgam is an interesting little reagent. Aluminum has a low electronegativity, which suggests that it would react very readily with anything mildly electron-hungry (such as the carbon atom of an imine, or the hydrogen atoms of water.) And yet, aluminum is considered corrosion-resistant under most conditions, to the point that it’s even used as shipping containers for nitric acid! That’s because, although aluminum does react readily, it tends to form aluminum oxide. 2-Chlorophenyl cyclopentyl ketone

This aluminum oxide forms a tightly interlocking crystalline layer over the remaining aluminum, sealing it off and protecting it from further reactions. Mercury is able to penetrate this protective oxide layer and prevent it from re-forming, which allows the aluminum to continue to react, contributing electrons to reduce whatever suitable chemical (oxygen, water, imines, etc.) happens to be handy.

This ability is the reason that you aren’t allowed to take or ship mercury on jets, which are usually made from aluminum. A spill of mercury could create a chemical ‘rot’ in the structure of the plane as the now unprotected aluminum continues to react with moisture and oxygen in the air.

Well, to brass tacks.

A not-so-theoretical ‘recipe’ for MDMA:

1. The daring (and perhaps soon to be incarcerated or incinerated) cook gets ahold of a little bit of real sassafras oil (not that easy to do these days in the US, but a thoughtful and clever person could likely figure out how to come up with perhaps 50 ml to play with at minimal risk/effort.) He vacuum distills it (or perhaps uses fractional freezing) to isolate the safrole, yielding about 40 ml of safrole. Sassafras oil is suspicious in ‘significant’ volumes; don’t try to order a liter of it. In fact, it’s best if you don’t order sassafras oil at all. Purified safrole is suspicious in any quantity and should never be ordered.

2. Next, let’s say they’re going to attempt a Wacker oxidation to get from safrole to MPK. This would normally be done with oxygen gas, but a less hardware-intensive method is to use benzoquinone as the oxidizer. So, in a 500 ml round bottom flask the daring cook mixes together: 40 g p-benzoquinone

100 ml methanol

0.5 g PdCl2 (palladium chloride)

12 ml distilled water

Generally 2-Chlorophenyl cyclopentyl ketone aren’t hard to get, although benzoquinone purchases may be reported by some sellers. As an exercise for students, try synthesizing PdCl2 from palladium metal with aqua regia. Contact Us.

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