3,4-Ethylenedioxythiophene (EDOT) is an

organosulfur compound Organosulfur chemistry is the study of the properties and synthesis of organosulfur compounds, which are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur der ...

with the formula C₂H₄O₂C₄H₂S. The molecule consists of

thiophene Thiophene is a heterocyclic compound with the formula C4H4S. Consisting of a planar five-membered ring, it is aromatic as indicated by its extensive substitution reactions. It is a colorless liquid with a benzene-like odor. In most of its reacti ...

, substituted at the 3 and 4 positions with an ethylene glycolyl unit. It is a colorless viscous liquid. EDOT is the precursor to the polymer

PEDOT Poly(3,4-ethylenedioxythiophene) (PEDOT or PEDT; ''IUPAC'' name poly(2,3-dihydrothieno ,4-''b''1,4]dioxane-5,7-diyl)) is a conducting polymer based on 3,4-Ethylenedioxythiophene, 3,4-ethylenedioxythiophene or EDOT. It was first reported by Bay ...

, which is found in electrochromism, electrochromic displays,

photovoltaic Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. The photovoltaic effect is commercially ...

s, electroluminescent displays, printed wiring, and sensors.

Synthesis and polymerization

The original synthesis proceeded via the diester of 3,4-dihydroxythiophene-2,5-dicarboxylate. EDOTsyn

EDOT is often prepared from C4 precursors such as

butanediol Butanediol, also called butylene glycol, may refer to any one of four stable structural isomers: * 1,2-Butanediol * 1,3-Butanediol * 1,4-Butanediol *2,3-Butanediol Geminal diols There are also two geminal diols (gem-diols), which are less stable: ...

and

butadiene 1,3-Butadiene () is the organic compound with the formula CH2=CH-CH=CH2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two ...

via routes that produce the thiophene and dioxane rings in separate steps. Representative is the reaction of 2,3-butanedione,

trimethyl orthoformate Trimethyl orthoformate (TMOF) is the organic compound with the formula HC(OCH3)3. A colorless liquid, it is the simplest orthoester. It is a reagent used in organic synthesis for the formation of methyl ethers. The product of reaction of an aldeh ...

, and

ethylene glycol Ethylene glycol ( IUPAC name: ethane-1,2-diol) is an organic compound (a vicinal diol) with the formula . It is mainly used for two purposes: as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odo ...

to form the dioxane. Sulfidization with elemental sulfur gives the bicyclic target. EDOT is converted into the

conducting polymer Conductive polymers or, more precisely, intrinsically conducting polymers (ICPs) are organic polymers that conduct electricity. Such compounds may have metallic conductivity or can be semiconductors. The main advantage of conductive polymers i ...

by oxidation. The mechanism for this conversion begins with production of the radical cation

DOT A dot is usually a small, round spot. Dot, DoT or DOT may also refer to: Orthography * Full stop or "period", a sentence terminator * Dot (diacritic), a mark above or below a character (e.g. ȧ, ạ, İ, Ċ, ċ, etc.), usually to indicate sou ...

sup>+, which attacks a neutral EDOT molecule followed by deprotonation. Further similar steps result in the dehydropolymerization. The idealized conversion using

peroxydisulfate The peroxydisulfate ion, , is an oxyanion, the anion of peroxydisulfuric acid. It is commonly referred to as persulfate, but this term also refers to the peroxomonosulfate ion, . It is also called ''peroxodisulfate''. Approximately 500,000 ton ...

is shown :n C₂H₄O₂C₄H₂S + n (OSO₃)₂²⁻ → ₂H₄O₂C₄Ssub>n + 2n HOSO₃⁻ For commercial purposes, the polymerization is conducted in the presence of polystyrenesulfonate.

References

{{DEFAULTSORT:Ethylenedioxythiophene, 3,4- Thiophenes Dioxanes