Epichlorohydrin equivalents

The tria2ine ring-containing product 1,3,5-triglycidyl isocyanurate (6) is synthesized by glycidylation of cyanuric acid with epichlorohydrin. The commercial product is a crystalline powder that exhibits an epoxy equivalent weight of ca 108 and softens in the 85—110°C range (see Cyanuric AND ISOCYANURIC acids). 

Mol. ratio epichlorohydrin bis-phenol A Mol. ratio NaOHl epichlorohydrin Softening point rc) Molecular weight Epoxide equivalent Epoxy groups per molecule... 

There are essentially three methods which have been used for incorporation of the glycerol unit in macrobicyclic species. In all of these the pervasive problem is the tendency of glycerol to form five-membered acetals involving the primary and secondary hydroxyls rather than the two primary hydroxyls and the tendency of the glycerol equivalent 1,3-dichloro-2-propanol to form epichlorohydrin. 

Assembling a five-component coupling product in a single operation further extended this methodology. Following alkylation of dithiane 78 with epoxide (—)79 (2.6 equivalent each) to generate the unrearranged alkoxy dithiane 80, sequential addition of HMPA and (—)-epichlorohydrin 81 (1 equivalent) furnished the bis(silyloxy dithiane) carbinols (- -)82 in 66% yield (equation 29) . ... 

The reaction actually involves the sodium salt of bisphenol A since polymerization is carried out in the presence of an equivalent of sodium hydroxide. Reaction temperatures are in the range 50-95°C. Side reactions (hydrolysis of epichlorohydrin, reaction of epichlorohydrin with hydroxyl groups of polymer or impurities) as well as the stoichiometric ratio need to be controlled to produce a prepolymer with two epoxide end groups. Either liquid or solid prepolymers are produced by control of molecular weight typical values of n are less than 1 for liquid prepolymers and in the range 2-30 for solid prepolymers. 

Depending on the conditions, reactions (I) and (II) can be carried out either concurrently or consecutively. If one works from the outset in alkaline medium, for example, by dropping the desired amount of epichlorohydrin into the mixture of hydroxy compound and the equivalent amount of aqueous alkali hydrox-... 

Reaction of 6-mercaptopurine with sodium bicarbonate and epichlorohydrin in ethanol for 7 days at room temperature gave the expected chlorohydrin derivative. Unexpectedly, when this was treated with two equivalents of sodium methoxide in methanol at room temperature for 24 hours it did not give either epoxide or methoxy containing derivatives. Instead, the product, obtained in 32% yield, was the substituted thietane 1. 

Epichlorohydrin (l-chloro-2,3-epoxypropane). Widely available. Used to epoxy activate the Sepharose CL-6B beads or other surfaces. The extent of epoxy activation of beads may be determined see Note 2). A high-purity (+99%) or equivalent should be used. It is a very unstable compound and must be stored at 0-4°C in an anhydrous environment. Hazards Flammable, poison, toxic by inhalation or contact with skin, and if swallowed may cause cancer. Toxicity data LD50 90 mg/kg oral, rat. Should be handled in a fume hood with safety glasses and gloves, and treated as a possible cancer hazard. 

Although considerable effort has been expended on asymmetric routes to the structural motif within a number of beta-blocker drugs, there has been little financial reward. Through the use of a chiral equivalent of epichlorohydrin (X = Cl), a substitution reaction at the sp3 center followed by epoxide opening allows for entry into this class of drugs. The stereogenic center of the epoxide is retained throughout this sequence (Scheme 22.8).11... 

Mole ratio epichlorohydrin/ bisphenol A Mole ratio NaOH/ epichlorohydrin Softening point, °C Molecular weight Epoxide equivalent Epoxy groups/ molecule... 

This new process features the hydrochlorination of glycerol with gaseous HC1 catalyzed by organic acids (Figure 2.2.9). First, monochlorohydrins are formed and, consequently, 1,3- and 2,3-dichlorohydrin. The reaction with base gives the desired epichlorohydrin under formation of only one equivalent of chloride salt. 

The HKR reaction is catalyzed by Co(III) complexes of the well-known Jacobsen salen ligand formed by the condensation of two equivalents of 3,5-di-tert-butylsali-cylaldehyde with either enantiomer of trans-1,2-diaminocyclohexane [6]. These catalysts show remarkable levels of selectivity and reactivity, and they can be indefinitely recycled with most substrates (epichlorohydrin being a notable exception). The counterion can be varied to enhance the reactivity of the catalyst with slow-re-acting substrates, but the initially reported acetate complex (X=OAc in Fig. 1) has proved to be the most broadly applicable catalyst [2],... 

The reaction of methylenetriphenylphosphorane with epichlorohydrin followed by addition of butyllithinm and an aldehyde in toluene provides alkylidenecyclo-butanols in moderate to good yield (Scheme 3). Similar reactions have previously been reported to afford alkylidenecyclo-propylmethanols (61) and the current report demonstrates that the reaction is highly base- and solvent-dependent. Further studies of the kinetics and mechanism of the addition of cyclopentadienylidenetriphenylphosphorane to tetrahalo-p-benzoquinones have included the reaction with tetraiodo-p-benzoquinone to give the 2,5-disubstituted quinone (62). Initial attack on sulfur is presumably involved in the reaction of two equivalents of stabilised phosphoranes with 5-arylimino-4-chloro-5H-1,2,3-dithiazoles (63) to give a mixture of N-arylcyanothioformamides (64) and, as the major product, the novel ylides (65). In one example the structure of (65) was confirmed by X-ray crystallography. 

Triglycidylp-AminophenoI DerivedResins. Resins derived from triglycidyl -aminophenol [5026-74-7] originally developed by Union Carbide Corp. (7) are currendy marketed by CIBA-GEIGY. Synthesis is conducted by reaction of epichlorohydrin with the phenoHc and amino groups followed by dehydrohalogenation. The product is a viscous Hquid (1.5-5 Pa-s (15—50 P) at 25 C) which is considerably more reactive toward amines than standard bisphenol A-derived resins. The epoxy equivalent weight is 105—114. 

Molar Ratio Epichlorohydrin/Bisphenol A Molecular Weight Epoxide Equivalent Softening Point (°C)... 

Depending on the conditions, reactions (I) and (E) can be carried out either concurrently or consecutively. If one works from the outset in alkaline medium, for example, by dropping the desired amount of epichlorohydrin into the mixture of hydroxy compound and the equivalent amount of aqueous alkali hydroxide at 50-100°C, then the addition reaction and the HQ elimination occur side by side (Example 4.24). On the other hand, if the hydroxy compound and epichlorohydrin are allowed to react in nonaqueous medium in the presence of acid catalysts, the corresponding chlorohydrin is first formed this can then be transformed into the epoxy compound in a second step by reaction with an equivalent amount of alkali hydroxide. 

Under similar conditions to those used in (a), 22.8 g (0.1 mol) of bisphenol A, 5.55 g (0.14 mol) of NaOH (dissolved in 56 ml water), and 11.3 g (0.123 mol) of epichlorohydrin are allowed to react with one another. Because of the smaller molar ratio of epichlorohydrin to bisphenol A (1.22) the resulting epoxy resin is of higher molecular weight than that produced in (a). The epoxy value is approximately 0.1, corresponding to 1.44 epoxy groups per molecule of resin (equivalent weight... 

Epoxide adhesives comprise epoxy resin, many of which are prepared from phenols and epichlorohydrin, for example, the diglycidyl ether of bis-phenol A or bis-phenol F usually, these resins are a mixtnre of molecular weights blended to fit the applications. The most-common cnratives for epoxy resins are polyanfines (used in stoichiometric amounts), usually a chain-extended primary aliphatic amine, for example, diethylene triamine or triethylene tetraamine or chain-extended equivalents, which react rapidly with the epoxy resin at room temperature. Aromatic amines react slowly at room temperature but rapidly at higher temperatures. Most epoxide adhesives also contain catalysts, typically, tertiary amines. Dicyanimide is the most-common curative for one-component high-temperature-cured epoxide adhesives. Mercaptans or anhydrides are used as curatives for epoxide adhesives for specialist applications, for example, for high-speed room-temperature cures or for electronic applications. A smaller number of epoxide adhesive are cured by cationic polymerization catalysed by Lewis acids photogenerated at the point of application. Lewis acid photoinitiators include diaryliodonium and triarly sulphonium salts. See Radiation-cured adhesives. 

Phenoxy resin (polyhdroxyether) n. Any linear thermoplastic resin made by reacting an exact equivalent of epichlorohydrin with bisphenol A and sodium hydroxide in dimethyl sulfoxide. 

A difficulty in the synthesis of the phosphorylide in the Wittig reaction is to add an equimolar amount of base to the alkyl halide. The use of epichlorohydrine, which forms one equivalent of base in situ by the reaction with iodide ions, obtained from the reaction of a C-labeled alkyl iodide with triphenyl phosphine is one method to overcome the problem. Some examples of useful precursors prepared from [ C] methyl iodide are shown in O Fig. 41.7. 

Epoxy phenolic adhesives are polyepoxy compounds which possess epoxy reactivity and phenolic resin heat resistance. These are prepared by condensing epichlorohydrin and novolac phenolics (phenol/formaldehyde ratio > 1). A recent Japanese patent issued to Mitsubishi Petrochemical Co. describes the preparation of epoxy resins from epichlorohydrin condensation with phenolic resins prepared from phenol and substituted aldehydes, e.g., vanillin. These resins (23) have high epoxy contents (epoxy equivalent weights >200) and relatively high softening points (85-95°C). 

---