Oxetane, or 1,3-propylene oxide, is a

heterocyclic A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, proper ...

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the molecular formula , having a four-membered ring with three carbon atoms and one

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

atom. The term "an oxetane" or "oxetanes" refer to any organic compound containing the oxetane ring.

Production

A typical well-known method of preparation is the reaction of

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...

with 3-chloropropyl acetate at 150 °C: Synthesis of trimethylene oxide

Yield of oxetane made this way is c. 40%, as the synthesis can lead to a variety of by-products including water, potassium chloride, and potassium acetate. Another possible reaction to form an oxetane ring is the Paternò–Büchi reaction. The oxetane ring can also be formed through

diol cyclization A diol is a chemical compound containing two hydroxyl groups ( groups). An aliphatic diol may also be called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified. They are used as protecting group ...

as well as through

decarboxylation Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2). Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is ...

of a six-membered

cyclic carbonate Cycle, cycles, or cyclic may refer to: Anthropology and social sciences * Cyclic history, a theory of history * Cyclical theory, a theory of American political history associated with Arthur Schlesinger, Sr. * Social cycle, various cycles in ...

Derivatives

More than a hundred different oxetanes have been synthesized. Functional groups can be added into any desired position in the oxetane ring, including fully fluorinated (perfluorinated) and fully deuterated analogues. Major examples are:

Taxol

Paclitaxel Paclitaxel, sold under the brand name Taxol among others, is a chemotherapy medication used to treat ovarian cancer, esophageal cancer, breast cancer, lung cancer, Kaposi's sarcoma, cervical cancer, and pancreatic cancer. It is administered b ...

(Taxol) is an example of a

natural product A natural product is a natural compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life. Natural products can also be prepared by chemical s ...

containing an oxetane ring. Taxol has become a major point of interest among researchers due to its unusual structure and success in the involvement of cancer treatment. The attached oxetane ring is an important feature that is used for the binding of microtubules in structure activity; however little is known about how the reaction is catalyzed in nature, which creates a challenge for scientists trying to synthesize the product.

Reactions

Oxetanes are less reactive than epoxides, and generally unreactive in basic conditions, although

Grignard reagents Grignard reagents or Grignard compounds are chemical compounds with the general formula , where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride and phenylmagnesium bromide ...

at elevated temperatures and complex hydrides will cleave them. However, the

ring strain In organic chemistry, ring strain is a type of instability that exists when bonds in a molecule form angles that are abnormal. Strain is most commonly discussed for small rings such as cyclopropanes and cyclobutanes, whose internal angles ar ...

does make them much more reactive than larger rings, and oxetanes decompose in the presence of even mildly acidic nucleophiles. In non-nucleophilic acids, they mainly isomerize to

allyl alcohol Allyl alcohol (IUPAC name: prop-2-en-1-ol) is an organic compound with the structural formula . Like many alcohols, it is a water-soluble, colourless liquid. It is more toxic than typical small alcohols. Allyl alcohol is used as a precursor to ...

Noble metal A noble metal is ordinarily regarded as a metallic chemical element, element that is generally resistant to corrosion and is usually found in nature in its native element, raw form. Gold, platinum, and the other platinum group metals (ruthenium ...

s tend to catalyze isomerization to a

carbonyl In organic chemistry, a carbonyl group is a functional group with the formula , composed of a carbon atom double bond, double-bonded to an oxygen atom, and it is divalent at the C atom. It is common to several classes of organic compounds (such a ...

. In industry, the parent compound, oxetane polymerizes to polyoxetane in the presence of a dry acid catalyst,Penczek & Penczek (1963), "Kinetics and mechanism of heterogeneous polymerization of 3,3-bis(chloromethyl)oxetane catalyzed by gaseous BF₃" in ''Die Makromolekuläre Chemie''. Wiley. although the compound was described in 1967 as "rarely polymerized commercially".

References

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Production

Derivatives

Taxol

Reactions

See also

References