# 2,4,5-Trimethoxyphenethylamine

2,4,5-Trimethoxyphenethylamine (2,4,5-TMPEA), also known as TMPEA-2 or as 4-methoxy-2,5-dimethoxyphenethylamine (2C-O or 2C-OMe), is a chemical compound of the phenethylamine and 2C families. It is a positional isomer of mescaline (3,4,5-trimethoxyphenethylamine) and is the α-desmethyl analogue of 2,4,5-trimethoxyamphetamine (TMA-2). The drug is the parent compound of the 2C-O series of drugs. 2C-O appears to be inactive in terms of psychoactive effects in humans. It was first described by Jansen in 1931.

## Chemistry

2C-O is a member of a class of chemical compounds commonly known as phenethylamines. Its full chemical name is 2-(2,4,5-trimethoxyphenyl)ethanamine; it is also known as 2,4,5-trimethoxyphenethylamine and 2,4,5-TMPEA.
A variety of derivatives of 2C-O, named 2C-O-2 (4-ethoxy-2,5-dimethoxyphenethylamine) through 2C-O-27, have been developed and studied. One particularly notable derivative is 2C-O-4 (4-isopropoxy-2,5-dimethoxyphenethylamine).

## Effects

2C-O at a dose of under 300 mg was reported to produce similar psychedelic effects as mescaline by Jansen in 1931, albeit with more nausea and no euphoria. Conversely, in a subsequent report, it was said to be indistinguishable from placebo at a dose of up to 300 mg. The present-day consensus appears to be that 2C-O is inactive. In PiHKAL, its dosage is listed as greater than 300 mg and its duration as unknown. Although 2C-O does not seem to produce effects by itself, 2C-O at a dose of 200 mg was reported to strongly potentiate the action of 100 mg mescaline when employed as pretreatment 45 minutes prior to the administration of mescaline. The apparent inactivity of 2C-O (2,4,5-trimethoxyphenethylamine) has been described as enigmatic, since other 2C drugs are active, since 2C-O's substituted amphetamine (α-methyl) counterpart 2,4,5-trimethoxyamphetamine (TMA-2) is active, and since its positional isomer mescaline (3,4,5-trimethoxyphenethylamine) is active.

## Dangers

The toxicity of 2C-O is not known.

## Pharmacology

It has been said that it is unclear whether the apparent inactivity of 2C-O is due to strong metabolism or low affinity and/or efficacy at the serotonin 5-HT$_{2A}$ receptor. However, an in-vitro study using rabbit liver tissue found that 2C-O was deaminated 25% alone and 25% with the monoamine oxidase inhibitor (MAOI) semicarbazide after 1 hour whereas mescaline was deaminated 60% alone and 0% with semicarbazide after 1 hour. These findings suggest that 2C-O may be less susceptible to metabolism by monoamine oxidase (MAO) than mescaline. Despite the inactivity of 2C-O and certain derivatives such as 2C-O-4, 2C-O derivatives show potent serotonin 5-HT$_{2A}$ receptor agonism in vitro and the amphetamine (α-methyl) analogue TMA-2 as well as derivatives like MEM are potent psychedelics in humans.

## History

2C-O was first described by Jansen in 1931 and was reported by him to produce psychedelic effects similar to those of mescaline. However, subsequent tests in the 1960s and 1970s suggested that 2C-O is actually inactive as a psychedelic in animals and humans.

## Legal status
### Canada

As of October 31, 2016, 2C-O is a controlled substance (Schedule III) in Canada.

### United States

2C-O is a Schedule I substance, as a positional isomer of mescaline.

### United Kingdom

2C-O and all other compounds featured in PiHKAL are Class A drugs in the United Kingdom.