A carbonate ester is a functional group

Functional group

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...

 in organic chemistry

Organic chemistry

Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...

 consisting of a carbonyl

Carbonyl

In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups....

 group flanked by two alkoxy groups. The general structure of these carbonates is R₁O(C=O)OR₂ and they are related to ester

Ester

Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...

s R₁O(C=O)R and ether

Ether

Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...

s R₁OR₂ and also to the inorganic

Inorganic chemistry

Inorganic chemistry is the branch of chemistry concerned with the properties and behavior of inorganic compounds. This field covers all chemical compounds except the myriad organic compounds , which are the subjects of organic chemistry...

 carbonate

Carbonate

In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....

s.

Carbonate esters are used as protecting group

Protecting group

A protecting group or protective group is introduced into a molecule by chemical modification of a functional group in order to obtain chemoselectivity in a subsequent chemical reaction...

 for diol

Diol

A diol or glycol is a chemical compound containing two hydroxyl groups A geminal diol has two hydroxyl groups bonded to the same atom...

s. A classic reagent is phosgene

Phosgene

Phosgene is the chemical compound with the formula COCl2. This colorless gas gained infamy as a chemical weapon during World War I. It is also a valued industrial reagent and building block in synthesis of pharmaceuticals and other organic compounds. In low concentrations, its odor resembles...

 but more user friendly reagents exist such as carbonyl diimidazole. Ethylene carbonate

Ethylene carbonate

Ethylene carbonate is an ester of ethylene glycol and carbonic acid. At room temperature ethylene carbonate is a transparent crystalline solid, practically odorless and colorless, and somewhat soluble in water. In the liquid state Ethylene carbonate is an ester of ethylene glycol and carbonic...

 and Propylene carbonate

Propylene carbonate

Propylene carbonate is an organic compound, a cyclic carbonate of propylene glycol. This colorless and odorless liquid is useful as a polar, aprotic solvent...

 are used as solvent

Solvent

A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...

s. Dimethyl carbonate

Dimethyl carbonate

Dimethyl carbonate, often abbreviated DMC, a carbonate ester, is a flammable clear liquid boiling at 90 °C. This compound has found use as a methylating agent and more recently as a VOC exempt solvent in paints and adhesives . There is also interest in using this compound as a fuel oxygenate...

 is used as a methylating

Methylation

In the chemical sciences, methylation denotes the addition of a methyl group to a substrate or the substitution of an atom or group by a methyl group. Methylation is a form of alkylation with, to be specific, a methyl group, rather than a larger carbon chain, replacing a hydrogen atom...

 reagent.

In many applications a carbonate group replaces an ester

Ester

Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...

 group for example in Cholesteryl oleyl carbonate

Cholesteryl oleyl carbonate

Cholesteryl oleyl carbonate is an organic chemical, an carbonate ester of cholesterol and oleyl alcohol with carbonic acid. It is a liquid crystal material forming cholesteric liquid crystals with helical structure. It is a transparent liquid, or a soft crystalline material with melting point...

. Polycarbonate

Polycarbonate

PolycarbonatePhysical PropertiesDensity 1.20–1.22 g/cm3Abbe number 34.0Refractive index 1.584–1.586FlammabilityV0-V2Limiting oxygen index25–27%Water absorption – Equilibrium0.16–0.35%Water absorption – over 24 hours0.1%...

s are an important class of polymers.

The chemistry of carbonate esters has been reviewed.

Organic synthesis

Laboratory methods for the synthesis of carbonate ester in the laboratory are:

• from the corresponding diols.
• by double oxidation of ketone
  Ketone
  In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...
  
  s in a Baeyer-Villiger rearrangement,although this method is plausible,there is no evidence that it is effective.
• by reaction of an epoxide
  Epoxide
  An epoxide is a cyclic ether with three ring atoms. This ring approximately defines an equilateral triangle, which makes it highly strained. The strained ring makes epoxides more reactive than other ethers. Simple epoxides are named from the parent compound ethylene oxide or oxirane, such as in...
  
    with carbon dioxide
  Carbon dioxide
  Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
  
   catalysed by a zinc halide

Use as solvents

A large number of organic carbonates are used as solvents . They are classified as polar solvent

Chemical polarity

In chemistry, polarity refers to a separation of electric charge leading to a molecule or its chemical groups having an electric dipole or multipole moment. Polar molecules interact through dipole–dipole intermolecular forces and hydrogen bonds. Molecular polarity is dependent on the difference in...

s and have a wide liquid temperature range. One example is polypropylene carbonate

Polypropylene carbonate

Polypropylene carbonate , also called poly, is a polyalkylene carbonate plastic material, a copolymer of carbon dioxide and propylene oxide. It is made by reacting the monomers in presence of eg. a zinc glutarate catalyst. Its CAS number is or .Polypropylene carbonate is soluble in polar solvents,...

 with melting point

Melting point

The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...

 - 55°C and boiling point 240 °C. Other advantages are low ecotoxicity

Ecotoxicity

Ecotoxicity, the subject of study of the field of ecotoxicology refers to the potential for biological, chemical or physical stressors to affect ecosystems...

 and good biodegradability. The industrial production of carbonates is not green because methods for production of linear carbonates rely on phosgene

Phosgene

Phosgene is the chemical compound with the formula COCl2. This colorless gas gained infamy as a chemical weapon during World War I. It is also a valued industrial reagent and building block in synthesis of pharmaceuticals and other organic compounds. In low concentrations, its odor resembles...

 and those of cyclic carbonates rely on propylene oxide

Propylene oxide

Propylene oxide is an organic compound with the molecular formula CH3CHCH2O. This colourless volatile liquid is produced on a large scale industrially, its major application being its use for the production of polyether polyols for use in making polyurethane plastics...

.

Use in batteries

Organic carbonates are used as a solvent in lithium batteries

Lithium battery

Lithium batteries are disposable batteries that have lithium metal or lithium compounds as an anode. Depending on the design and chemical compounds used, lithium cells can produce voltages from 1.5 V to about 3.7 V, over twice the voltage of an ordinary zinc–carbon battery or alkaline battery...

; due to their high polarity they can dissolve lithium salts. The problem of high viscosity is circumvented by using carbonate mixtures for example mixtures of dimethyl carbonate, diethyl carbonate and dimethoxy ethane.