Ester and ether are organic molecules with oxygen atoms. The main difference between ether and ester lies in their structure.An ester group requires two oxygen atoms and two carbon atoms to complete its characteristic structure, while an ether group only needs one oxygen atom and two carbon atoms for its structure. Read this article, to find more details about how ethers and esters differ in their structure, physical and chemical properties together with their real-life applications.
What Are Ethers?
Ethers are a class of organic compounds that mostly contain an ether group wherein the oxygen atom is bonded to two alkyl or aryl groups. The word Ether has been derived from the Latin word ‘aether’ which means ‘to ignite’. At room temperature and under a high-pressure ethers are usually flammable. The general formula of ether is given as R-O-R, R-O-R’, R-O-Ar or Ar-O-Ar where R represents an alkyl group and Ar represents an aryl group.
Ethers can again be classified into two varieties: if the alkyl or aryl groups are the same on both sides of the oxygen atom, then it is a simple or symmetrical ether, whereas if they are different, the ethers are called mixed or unsymmetrical ethers.
Ethers are similar in structure to alcohols, and both ethers and alcohols are similar in structure to water. In an alcohol one hydrogen atom of a water molecule is replaced by an alkyl group, whereas in an ether both hydrogen atoms are replaced by alkyl or aryl groups.
At room temperature, ethers are pleasant-smelling colourless liquids. Relative to alcohols, ethers are generally less dense, are less soluble in water, and have lower boiling points.
They are relatively unreactive, and as a result they are useful as solvents for fats, oils, waxes, perfumes, resins, dyes, gums and hydrocarbons. Vapours of certain ethers are used as insecticide, miticides and fumigants for soil.
What are Esters?
An ester is a chemical compound derived from an acid (organic or inorganic) in which at least one –OH hydroxyl group is replaced by an –O– alkyl (alkoxy) group. To put it in simple terms, esters are a group of chemical compounds which are formed by bonding of an alcohol group with a group of organic acids, by losing water molecules. The termesterwas introduced in the first half of the 19th century by German chemist Leopold Gmelin.
Esters feature a carbon-to-oxygen double bond that is also singly bonded to a second oxygen atom. The oxygen atom is further connected to an aryl or an alkyl group. They come in all shapes and sizes. They can have a form as small as that of allyl hexanoate like pineapple odour or as large as a long-chain triglyceride, like soybean oil.
Esters are named as if the alkyl chain from the alcohol is a substituent. No number is assigned to this alkyl chain. This is followed by the name of the parent chain from the carboxylic acid part of the ester with an–eremove and replaced with the ending–oate.
Esters typically have a pleasant smell; those of low molecular weight are commonly used as fragrances and are found in essential oils and pheromones. They perform as high-grade solvents for a broad array of plastics, plasticisers, resins and lacquers and are one of the largest classes of synthetic lubricants on the commercial market.
- An ester is a chemical compound derived from an acid (organic or inorganic) in which at least one-OH (hydroxyl) group is replaced by an –O-(alkyl) group. An ether is any a class of organic compounds that contain an oxygen atom bonded to two alkyl groups.
- Esters are prepared in a laboratory using a process known as esterification. They can also be produced through alcoholysis of acyl chlorides and acid anhydrides. Ethers are produced in laboratory using several methods among which include dehydration of alcohols and the Williamson ether synthesis.
- Ethers are compounds characterized by an oxygen atom sandwiched between two alkyl or aryl groups. The general structure is R-O-R’, where R and R’ represent alkyl or aryl groups.Esters are compounds derived from carboxylic acids by replacing the -OH group with an -OR group. The general structure is R-CO-O-R’, where R represents an alkyl or aryl group and R’ represents an alkyl group.
- Ethers are named by listing the two alkyl or aryl groups attached to the oxygen atom, followed by the word “ether.” For example, ethyl methyl ether. Esters are named by listing the alkyl or aryl group attached to the carbonyl carbon (from the carboxylic acid) first, followed by the name of the alkyl or aryl group attached to the oxygen, with the word “ate” replacing the “ic acid” ending. For example, methyl ethanoate (formerly known as methyl acetate).
- Ethers have relatively a low chemical reactivity; they do not readily react with dilute acids, bases, active metals, reducing agents and oxidizing agents. Esters are highly reactive, they readily react with acids, bases, active metals, oxidizing agents and reducing agents.
- Ethers are relatively inert to hydrolysis under normal conditions. Esters can undergo hydrolysis under acidic or basic conditions, producing a carboxylic acid and an alcohol.
- Many ethers are volatile liquids at room temperature. Esters can exist as liquids, solids, or volatile compounds depending on their molecular weight and structure.
- Ethers have relatively low boiling points due to their inability to form hydrogen bonds with each other. Esters have a relative higher boiling point because ester molecules can engage in hydrogen bonding with each other.
- Ethers are often colorless and have a characteristic, sweet, and sometimes “ether-like” odor.Esters are responsible for many fruity and floral odors and flavors found in natural and synthetic fragrances and flavorings.
- Due to the fact that water is polar in nature and ether is non-polar. Ethers are slightly soluble in water because the presence of oxygen in ethers which interact with hydrogen in water to produce hydrogen bonding to make it slightly soluble in water. Small esters are fairly soluble in water but solubility falls with chain length. The reason for the solubility is that although esters cannot hydrogen bond with themselves, but they can hydrogen bond with water molecules.
- It is not possible for esters to have symmetrical structures due to the presence of carbonyl group. Conversely, if both alkyl groups on either side of the oxygen atom in ether group are similar, and therefore the structure is symmetrical.
- Esters are derived from carboxylic acids whereas, ethers are derived from alcohols.
- Ethers have historically been used as solvents and anesthetics. Diethyl ether, for example, was used as an anesthetic in the past. Esters have a wide range of uses, including being used as flavor and fragrance compounds, plasticizers, solvents, and in the production of various chemicals.
- Examples of Esters include ethyl ethanoate, ethyl propanoate, propyl methanoate, propyl ethanoate and methyl butanoate. Examples of ethers include diethyl ether, methyl ethyl ether diphenyl ether, polyethylene glycol, Anisole, Dioxane, ethylene oxide and diisopropyl ether.
Esters vs Ether: Key Differences
|The ether functional groups have an oxygen atom that forms a single bonds with two carbon atoms||The ester functional groups have a carbonyl group bonded to an oxygen atom which is further bonded to an alkyl group|
|The general formula of ethers is R-O-R’||The general formula of esters is RCOOR’|
|Ethers may be symmetrical or asymmetrical||Esters are always asymmetrical|
|Ethers are named as “alkoxy alkanes”||The name of esters end with a suffix “-ate”|
|Their melting and boiling points are lower than esters||Their melting and boiling points are higher than ethers|
|They are derived from alcohols||They are derived from carboxylic acids|
|Ethers contain sigma bonds only||Esters contain sigma as well as pi bonds|
|They are less reactive than esters||They are more reactive than ethers|
|Ethers are hydrolyzed into alcohols||Esters are hydrolyzed into alcohols and carboxylic acid|
|They have sweet and slightly pungent smell||Esters have fruity smell|
|They are non-polar in nature||Esters are polar compounds|
|They can be used as anesthetics||They can be used as synthetic flavors and perfumes|
|For example (CH3-O-CH3) Dimethyl ether (C2H5-O-C2H5) Diethyl ether||For example (CH3COOCH3) Methyl methanoate (C2H5COOC2H5) Ethyl ethanoate|
- Ethers have an oxygen atom (O) between two alkyl or aryl groups (R-O-R’). Esters have a carbonyl group (C=O) between an alkyl or aryl group and an oxygen atom (R-CO-O-R’).
- The functional group of ethers is the ether linkage (-O-). The functional group of esters is the ester linkage (-CO-O-).