Chlorendic anhydride

Chlorendic Acid. Chlorendic acid [115-28-6] and its anhydride [115-27-5] are widely used flame retardants. Chlorendic acid is synthesized by a Diels-Alder reaction of maleic anhydride and hexachlorocyclopentadiene (see CyclopentadlENE and dicyclopentadiente) in toluene followed by hydrolysis of the anhydride using aqueous base (60). The anhydride can be isolated directly from the reaction mixture or can be prepared in a very pure form by dehydration of the acid. The principal use of chlorendic anhydride and chlorendic acid has been in the manufacture of unsaturated polyester resins. Because the esterification rate of chlorendic anhydride is similar to that of phthalic anhydride, it can be used in place of phthalic anhydride in commercial polyester... 

Halogenated intermediates, dibromoneopentyl glycol [3296-90-0] (DBNPG), and alkoxylated derivatives of tetrabromobisphenol A are used extensively in flame-retardant apphcations. Similar properties can be derived from halogenated dibasic acids, chlorendic anhydride [115-27-5] (CAN), and tetrabromophthahc anhydride [632-79-1] (TBPA). Processes can be used to produce brominated products by the in situ bromination of polymers derived from tetrahydrophthahc anhydride. 

Flame-Retardant Resins. Flame-retardant resins are formulated to conform to fire safety specifications developed for constmction as well as marine and electrical appHcations. Resins produced from halogenated intermediates (Table 5) are usually processed at lower temperatures (180°C) to prevent excessive discoloration. Dibromoneopentyl glycol [3296-90-0] (DBNPG) also requires glass-lined equipment due to its corrosive nature. Tetrabromophthahc anhydride (TBPA) and chlorendic anhydride (8) are formulated with ethylene glycols to maximize fiame-retardant properties reaction cycle times are about 12 h. Resins are also produced commercially by the in situ bromination of polyester resins derived from tetrahydrophthahc anhydride... 

Halogenated intermediates based on chlorendic anhydride and alkoxylated, brominated bisphenol are quite stable and are used extensively in flame-retarded high temperature compositions, but brominated aUcychcs, such as dibromotetrahydrophthahc resin, are rapidly dehydrohalogenated at lower temperatures. 

Chlorendic anhydride is the common name of the Diels-Alder adduct of maleic anhydride and hexachlorocyclopentadiene, 3,4,5,6,7,7-hexachloroendomethylene-l,2,3,6-tetrahydrophthahc anhydride (HET). The resultant resins from HET contribute to the flame retardancy of the alkyd coatings. HET gives a greater reaction rate than phthaUc anhydride, to the extent that at 204—210°C the reaction rate approximates that of phthaUc anhydride at a temperature of 238°C (8). However, the resins tend to develop darker color, particularly at high processing temperature. Tetrachlorophthahc anhydride [117-08-8] made by conventional chlorination of phthaUc anhydride, would also impart flame retardancy to its alkyds. However, it is appreciably less soluble in the usual processing solvents than is phthaUc anhydride, and is reported to be of appreciably lower chemical reactivity (8). 

Flame Retardants. Although the use of chlorinated derivatives of DCPD has been restricted in the pesticide area, some are widely used in flame and fire retardant chemicals (see Flame retardants). The starting material is the fliUy chlorinated DCPD cracked to monomeric hexachlorocyclopentadiene, which is then converted via a Diels-Alder reaction with maleic anhydride to a reactive bicycHc anhydride (9), known as chlorendic anhydride [115-27-5]. 

This anhydride can then be esterified with polyols yielding a polyester with a residual double bond available for further reaction. AppHcations for chlorendic anhydride derivatives are in polymers for building materials, paints, and other coatings. 

Chlorendic anhydride (l,4,5,6,7,7,-hexachloro-5-norbornene-2,3-dicarboxylic anhydride) [115-27-5] M 370.9, m 234-236 . 235-237 , 238 . Steam distn or recrystn from H2O yields the diacid. The purified diacid yields the anhydride with AC2O. [Prill 7 A/w Chem Soc 69 62 1947.]... 

Other anhydrides that have been used include dodecenylsuccinic anhydride, which imparts flexibility into the casting, and chlorendic anhydride, where flame-resistant formulations are called for. 

We have recently evaluated the chlorendic imide/hindered phenol for its effect on the oxygen index of polyethylene, and we found only a miniscule increase, not considred statistically significant, in comparison to the same loading of chlorine as chlorendic anhydride. We believe that if the antioxidant approach to flame retardancy is to be successful, special high temperature antioxidant structures must be designed for this purpose. 

Cetyl alcohol, h35 Cetyl bromide, b345 Chalcone, d768 Chloral, t218 Chloramine T, c258 Chloranil, t34, t35 Chlorendic anhydride, h28... 

Chlorendic acid, 11 479 Chlorendic anhydride, 8 232 CHLOREP program, 25 343 Chlorfenapyr, 14 349 Chlorfluren methyl ester, 13 44t Chlorfurenol methyl ester, 13 44t Chlorhexidine gluconate, 8 340 Chloric acid, 6 103-120 8 544 chemical properties, 6 104 manufacture, 6 104-105 physical properties, 6 103-104 uses, 6 105-106... 

Uses Intermediate in the synthesis of dyes, cyclodiene pesticides (aldrin, dieldrin, endosulfan), fungicides, and pharmaceuticals manufacture of chlorendic anhydride and chlorendic acid. 

Chlorendic anhydride (l,4,5,6,7,7,-hexachloro-5-norbornene-2,3-dicarboxy ic anhydride)... 

Scheme 8 Imprinting approach used to catalyse the reaction between tetrachlorothiophene dioxide (43) and maleic anhydride (44) to give (45). The chlorendic anhydride (46), representing the TSA, is used as the template for imprinting.

In 1997 the same group developed the first imprinted polymer able to catalyse a Diels-Alder reaction between tetrachlorothiophene dioxide (43) and maleic anhydride (44) to give the product (45). The imprinting strategy was inspired by previous work carried out by Hilvert et al. in 1989 for the development of catalytic antibodies with Diels-Alder capabilities [26]. The chlorendic anhydride (46) was used as a template because of its structural analogy with the transition state of the reaction (TSA). The resulting imprinted polymer showed a Michaelis-Menten behaviour and a ratio kcal/kunca equal to 270 (Scheme 8). 

The main reactive flame-retardant compounds used in unsaturated polyesters are tetrabro-mophthalic anhydride, dibromoneopentyl glycol, bis(2-hydroxyethyl) ether of tetrabromobisphenol A, and chlorendic anhydride. Tetrachlorophthalic anhydride is also used. 

Polymer Structure Modification. Chemical modification of the polymer structure includes the use of tetrahalophthalic acids or anhydrides, diallylphenyl phosphonate, brominated allyl phosphates, chlorendic anhydride, and tetrakishydroxymethyl phosphonium chloride. 

Chlorines Chlorinated paraffins Tris (dichloropropyl) phosphate, methyl pentachlorostearate, and other chlorinated phosphates Cycloaliphatic chlorine Chlorendic anhydride LDPE film and flexible PVC Urethane foam and topical fabric Polypropylene and nylon Reactive intermediate in making polyester and epoxy flame-retardant resins Amspec Chemical, Asahi Denka Kogyo, ICC Industries-Dover, Kettlitz Chemie, Lehmann Voss, OxyChem, Polytechs... 

Although they are more difficult to formulate into epoxy adhesive systems, anhydride cured epoxies have somewhat better thermal stability than amine cured systems. Aromatic and cyclic anhydrides, such as phthalic anhydride, pyromellitic dianhydride, and chlorendic anhydride, provide the most stable structures. 

Velsicol Chemical LLC, formerly Velsicol Chemical Corporation, designs, manufactures, markets and distributes high performance specialty chemicals and industrial intermediates, primarily based on benzoic acid and the organic compound cyclopentadiene. Its products include chlorendic anhydride and hexachlorocyclopentadiene (HEX). Chlorendic anhydride is corrosion resistant, fire resistant and has high UV stability, and is used in the synthesis of flame retardant polymers such as polyurethanes, unsaturated polyester and epoxy resins. HEX, a reactive intermediate used in the manufacture of agricultural pesticides in the production of flame retardants for the wire and cable industry and in the preparation of chlorendic anhydride. The company s products are produced primarily at a plant in Memphis, Tennessee Velsicol also maintains the Memphis Environmental Center (MEC), which focuses on managing legacy environmental liabilities. The firm is owned by Arsenal Capital Partners, a private equity firm. 

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