Bisphenol A diglycidyl ether (commonly abbreviated BADGE or DGEBA) is an

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 ...

and is a liquid

epoxy resin Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also co ...

. The compound is a colorless viscous liquid (commercial samples can appear pale straw-coloured). It is a key component of many epoxy resin formulations. Addition of further Bisphenol A and a catalyst and heat can produce Bisphenol A glycidyl ether epoxy resins of higher molecular weight that are solid. Epoxy prepolymer chemical structure

Preparation and reactions

It is prepared by O-

alkylation 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 al ...

bisphenol A Bisphenol A (BPA) is a chemical compound primarily used in the manufacturing of various plastics. It is a colourless solid which is Solubility, soluble in most common organic solvents, but has very poor solubility in water. BPA is produced on a ...

with

epichlorohydrin Epichlorohydrin (abbreviated ECH) is an organochlorine compound and an epoxide. Despite its name, it is not a halohydrin. It is a colorless liquid with a pungent, garlic-like odor, moderately soluble in water, but miscibility, miscible with most p ...

. This reaction mainly affords bisphenol A diglycidyl ether, as well as some

oligomer In chemistry and biochemistry, an oligomer () is a molecule that consists of a few repeating units which could be derived, actually or conceptually, from smaller molecules, monomers.Quote: ''Oligomer molecule: A molecule of intermediate relativ ...

. The

degree of polymerization The degree of polymerization, or DP, is the number of structural unit, monomeric units in a macromolecule or polymer or oligomer molecule. For a homopolymer, there is only one type of monomeric unit and the ''number-average'' degree of polymeriza ...

may be as low as 0.1. The epoxide content of such epoxy resins is of interest. This parameter is commonly expressed as the epoxide number, which is the number of epoxide equivalents in 1 kg of resin (Eq./kg), or as the equivalent weight, which is the weight in grams of resin containing 1 mole equivalent of epoxide (g/mol). Since unsymmetrical epoxides are

chiral Chirality () is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek language, Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is dist ...

, the bis epoxide consists of three

stereoisomers In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms i ...

, although these are not separated. Bisphenol A diglycidyl ether slowly hydrolyzes to 2,2-bis (2,3-dihydroxypropoxy)phenyl)propane (bis-HPPP). Similarly, DGEBA reacts with acrylic acid to give vinyl ester resins. The reaction results in opening of the epoxide ring, generating unsaturated esters at each terminus of the molecule. Such materials are often diluted with styrene and converted to resin. Epoxy resins are thermosetting polymers, which are crosslinked using hardeners (curing agents). The most common curing agents for epoxy resins are polyamines, aminoamides, and phenolic compounds.Forrest, M.J.: Coatings and Inks for Food Contact Materials, in RAPRA review reports, vol. 16, no. 6 (2005), p.8

Safety

BADGE is highly reactive and forms a number of species upon exposure to water or HCl and many of these compounds (including BADGE) are suspected

endocrine disruptor Endocrine disruptors, sometimes also referred to as hormonally active agents, endocrine disrupting chemicals, or endocrine disrupting compounds are chemicals that can interfere with endocrine (or hormonal) systems. These disruptions can cause ...

s. Hydrolysis of the

ether In organic chemistry, ethers are a class of compounds that contain an ether group, a single oxygen atom bonded to two separate carbon atoms, each part of an organyl group (e.g., alkyl or aryl). They have the general formula , where R and R� ...

bonds liberates bisphenol A, which is also strongly suspected of being an endocrine disruptor. From the 1990s onward, concern has been raised over the use of BADGE-based epoxy resins in the lining of some cans for foodstuffs, with the chemical being found to leach into foods. Bisphenol A Diglycidyl ether-based epoxy coatings are extensively used for coating the inside of cans which come into contact with food and are thus

food contact materials Food contact materials or food contacting substances (FCS) are materials that are intended to be in contact with food. These can be things that are quite obvious like a glass or a can for soft drinks as well as machinery in a food factory or a ...

. The materials and analogues and conjugates have been extensively tested for and analytical methods developed.

References

{{Glycidyl ethers Glycidyl ethers IARC Group 3 carcinogens Nonsteroidal antiandrogens Phenol ethers PPAR agonists 2,2-Bis(4-hydroxyphenyl)propanes

Preparation and reactions

Safety

See also

References