Ethyl Bromoacetate
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Ethyl bromoacetate is the
chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
with the formula . It is the ethyl
ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...
of
bromoacetic acid Bromoacetic acid is a chemical compound with the formula . This colorless solid is a relatively strong alkylating agent. Bromoacetic acid and its esters are widely used building blocks in organic synthesis, for example, in pharmaceutical chemistry ...
and is prepared in two steps from
acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...
. It is a lachrymator and has a fruity, pungent odor. It is also a highly toxic
alkylating agent Alkylation is a chemical reaction that entails transfer of an alkyl group. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting ...
and may be fatal if inhaled.


Applications

Ethyl bromoacetate is listed by the
World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...
as a riot control agent, and was first employed for that purpose by French police in 1912. The French army used rifle grenades 'grenades lacrymogènes' filled with this gas against the Germans beginning in August 1914, but the weapons were largely ineffective, even though ethyl bromoacetate is twice as toxic as chlorine. In the early months of the war the British also used the weaponized use of tear gas agents and more toxic gasses including
sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...
. The German army then used these attacks to justify their subsequent employment of it as
odorant An aroma compound, also known as an odorant, aroma, fragrance, flavoring or flavor, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficien ...
or warning agent in odorless, toxic gases and
chemical weapon A chemical weapon (CW) is a specialized munition that uses chemicals formulated to inflict death or harm on humans. According to the Organisation for the Prohibition of Chemical Weapons (OPCW), this can be any chemical compound intended as ...
s in 1915 under the German code '' Weisskreuz'' (White Cross). In
organic synthesis Organic synthesis is a branch of chemical synthesis concerned with the construction of organic compounds. Organic compounds are molecules consisting of combinations of covalently-linked hydrogen, carbon, oxygen, and nitrogen atoms. Within the gen ...
, it is a versatile
alkylating agent Alkylation is a chemical reaction that entails transfer of an alkyl group. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting ...
. Its major application involves the Reformatsky reaction, wherein it reacts with
zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...
to form a zinc
enolate In organic chemistry, enolates are organic anions derived from the deprotonation of carbonyl () compounds. Rarely isolated, they are widely used as reagents in the Organic synthesis, synthesis of organic compounds. Bonding and structure Enolate ...
. The resulting condenses with
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 ...
compounds to give a β-hydroxy-esters. It is also the starting point for the preparation of several other reagents. For example, the related Wittig reagent (prepared by reaction with triphenylphosphine) is commonly used to prepare alpha,beta- unsaturated
ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...
s from carbonyl compounds such as
benzaldehyde Benzaldehyde (C6H5CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is among the simplest aromatic aldehydes and one of the most industrially useful. It is a colorless liquid with a characteristic almond-li ...
:A student lab procedure for the Wittig sequence shown, only using the related methyl ester.


References


Footnotes


External links


Environmental Health & Safety dept, Northeastern University
{{Chemical agents Alkylating agents Ethyl esters Acetate esters Organobromides Lachrymatory agents World War I chemical weapons Reagents for organic chemistry
Organic Chemistry