United States Patent (19) (11) 4,284,573 Arnett Et Al
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United States Patent (19) (11) 4,284,573 Arnett et al. 45) Aug. 18, 1981 54 PREPARATION OF GLYCIDYL ETHERS OTHER PUBLICATIONS 75 Inventors: John F. Arnett, Newton; George A. Chemical Abstracts, vol. 87 (1977) 22359X. Doorakian, Bedford, both of Mass. Primary Examiner-Norma S. Milestone 73) Assignee: The Dow Chemical Company, Attorney, Agent, or Firm-Michael L. Glenn Midland, Mich. 57 ABSTRACT 21 Appl. No.: 80,769 A process for producing glycidyl ethers of phenols is described which comprises the steps of: (22 Filed: Oct. 1, 1979 (1) reacting by contacting, in liquid phase, a phenol with excess epichlorohydrin in the presence of a catalytic 5ll Int. Cl............................................. CO7D 301/28 amount of tetrahydrocarbyl phosphonium bicarbon 52 U.S. Cl. ........................... 260/348.15; 260/348.19 ate salt, to thereby produce a coupled reaction prod 58) Field of Search ...................... 260/348.15, 348.18, uct comprising the corresponding propylene 260/348.19 chlorohydrin ether of said phenol; (2) devolatilizing said coupled reaction product to re 56) References Cited move excess epichlorohydrin and volatile by-pro U.S. PATENT DOCUMENTS ducts; and (3) contacting the devolatilized reaction product from 3,948,855 4/1976 Perry ............................... 260/47 EP Step (2) with aqueous base, thereby converting the 3,992,432 11/1976 Napier et al. ... 260/348.31 . propylenechlorohydrin groups of the coupled reac 3,996,259 12/1976. Lee et al. ..... ... 260/348.18 tion product to glycidyl ether groups. FOREIGN PATENT DOCUMENTS This process is particularly useful in preparing low 893.191 7/1970 Canada . molecular weight liquid epoxy resins by the reaction of 2335199 1/1975 Fed. Rep. of Germany ...... 260/348.15 epichlorohydrin with bisphenol A. 2533505 12/1976 Fed. Rep. of Germany ...... 260/348.15 1019565 2/1966 United Kingdom ................ 260/348.15 10 Claims, No Drawings 4,284,573 1 2 teaches that the coupling reaction should be conducted PREPARATION OF GLYCDYL ETHERS at temperatures less than 60° C. At temperatures in excess of 60° C., undesirable polymeric compounds are BACKGROUND OF THE INVENTION formed. 1. Field of the Invention Others have utilized sulfonium salts (e.g., British Pat. This invention pertains to a process of making glyci No. 1,019,565), tertiary amines or quaternary ammo dyl ethers of phenolic compounds by the reaction of nium salts as catalysts for the coupling reaction (e.g., epichlorohydrin with the phenols. More particularly, British Pat. No. 897,744) and still others have utilized this invention pertains to a process for making low phosphonium salts (German AUS. No. 2,335, 199) and molecular weight liquid epoxy resins from the reaction 10 /or phosphoranes (e.g., German Offen. No. 2,533,505). of epichlorohydrin with polyhydric phenols. The latter two German references are the closest prior 2. Prior Art art relative to step one in the instant process in that The prior art is replete with techniques of preparing these references do at least use catalysts containing glycidyl ethers of phenols and particularly for prepar phosphorus. ing glycidyl ethers of polyhydric phenols. 15 The dehydrochlorination step has also been the sub The usual preparation of glycidyl ethers of phenols ject of investigation. Smith (U.S. Pat. No. 3,372,442) involves the reaction of epichlorohydrin with a phenol teaches that the dehydrochlorination is facilitated by in the presence of an alkali metal hydroxide, as repre using an aqueous sodium hydroxide solution which is sented by the following equation: substantially saturated with sodium carbonate. Becker 20 (U.S. Pat. No. 3,980,679) teaches that the dehydrochlo R rination is facilitated by adding solid alkali metal hy O droxide incrementally to the reaction mixture. / N None of the aforementioned references teach that Cl-H2C-HC - CH2 + HO - NaOH there is any advantage in conducting the dehydrochlo 25 rination step in the presence of a quaternary onium salt nor do they indicate what effect, if any, the residual O quaternary onium salts or other catalysts have on the / N reaction product or on this particular step of the overall H2C - CH-CH2-O -- NaCl -- H2O reaction. It is known, however, that amines and quater 30 nary ammonium salts are capable of causing degrada The stoichiometry of the reaction requires one equiva tion of the epoxides. And at least one of the references lent of epichorohydrin and one equivalent of base per specifically teaches that the catalyst for the coupled phenolic hydroxyl group. However, excessive amounts reaction should be removed from the reaction mixture of undesirable by-products are produced if one uses a 35 prior to the dehydrochlorination reaction (British Pat. stoichiometric ratio of reactants. To maximize the yield No. 897,744). The other references are not as explicit in of the glycidyl ether, excess epichlorohydrin and excess their written description but convey the same teaching base have been used to a substantial advantage. One of in that they wash the coupling reaction product with the major problems associated with the use of excess water to remove the catalyst and/or water-soluble by epichlorohydrin has been the recovery of unreacted 40 products, (e.g., sodium chloride and other salts) before epichlorohydrin from the reaction product. the dehydrochlorination step. Still other references A typical multistep method for preparing glycidyl handle the problem by passing the glycidyl ether of the ethers of phenols which results in the production of low phenol through various clays or other materials to ab molecular weight epoxy resins is described in U.S. Pat. sorb the residual catalyst from the reaction product. No. 2,943,095 (Farnham et al.). Farnham et al. con 45 The glycidyl ethers of phenols can be prepared ac ducted the reaction of epichlorohydrin with a polyhyd cording to the above techniques using either batch pro ric phenol in two steps: In the first step, the phenol is cesses or by continuous processes. This is illustrated by reacted with excess epichlorohydrin in the presence of the above references and by German Pat. No. 2,522,745 a base (e.g., lithium chloride, lithium acetate and alkali and German Pat. No. 2,523,696. metal hydroxides) to give a product comprising the 50 propylene chlorohydrin of the phenol. This reaction is SUMMARY OF THE INVENTION generally referred to as the coupling reaction. Farnham A process for producing glycidyl ethers of phenols et al. report that in stage one, the reaction temperature has now been discovered which comprises the steps of: should not exceed 45 C. In step two, the coupled reac (a) introducing a catalytic amount of a tetrahydrocar tion product is dehydrohalogenated with a strong base 55 by phosphonium bicarbonate salt into a liquid phase to form the corresponding glycidyl ether of the phenol. mixture of a phenol with excess epichlorohydrin to This dehydrohalogenation is normally performed in a thereby produce at reactive conditions a coupled reac mixture of liquids comprising a volatile water-soluble 'tion product comprising the corresponding propylene alcohol or ketone and a water-immiscible liquid. Farn chlorohydrin ether of said phenol; and ham et al. recover excess epichlorohydrin by distillation (b) contacting the coupled reaction product in a liq between steps one and two. uid organic solvent with sufficient aqueous base in the Many other patents have issued which also use a presence of a catalytic amount of the tetrahydrocarbyl multistep reaction and which teach that various cata phosphonium bicarbonate salt or its in situ derivative lysts may be used to promote the coupling reaction. salts from step (a) to convert the propylenechlorohy Reinking et al. (U.S. Pat. No. 2,943,096) indicate that 65 drin groups to the corresponding glycidyl ether groups. the coupling step is greatly facilitated by conducting the The glycidyl ethers prepared in the above-described reaction under anhydrous conditions in the presence of manner are advantageous because of their excellent a quaternary ammonium salt catalyst. This reference color and purity. Epoxy resins produced by this process 4,284,573 3 moveover have the advantage of a low total organic chloride content and a narrow molecular weight distri R R R R I bution that corresponds closely to theory. DETAILED DESCRIPTION OF THE HO X OH INVENTION Phosphonium Bicarbonate Salts R R R R The tetrahydrocarbyl phosphonium bicarbonate salts O wherein each R independently is hydrogen, halogen correspond to the formula I (fluoro, chloro or bromo) or a hydrocarbyl radical and X is oxygen, sulfur, -SO-, -SO2-, bivalent hydro carbon radicals containing up to about 10 carbon atoms, and oxygen-, sulfur- and nitrogen-containing hydrocar R.--R, HCO3G, 15 bon radicals, such as -OR'O-, -OR'OR'O-, -S-R'-S-, -S-R'-S-R-S-, -OSiO-, -OSiOSiO-, wherein R1, R2, R3 and R4 independently are hydro O O carbyl or inertly-substituted hydrocarbyl radicals, hav 20 ing from 1 to about 20 carbon atoms. R1, R2, R3 and R4. are preferably C1 to C12 alkyl groups or phenyl and and -SO2-R'-SO2-radicals wherein R is a bivalent more preferably are C1 to C4 alkyl or phenyl. More hydrocarbon radical. 4,4'-Isopropylidenediphenol (i.e., preferably R1-R3 are each phenyl groups and R4 is an bisphenol A) is the most preferred phenol. n-butyl group. Most preferably R1-R3 are each n-butyl 25 groups and R4 is a methyl group. COUPLING REACTION: STEP (A) Compounds of the formula I are conveniently pre The process for preparing glycidyl ethers of phenols pared by reacting at room temperature a tetrahydrocar consists of two distinct reactions-coupling (Step (a)) and dehydrochlorination (Step (b)). These reactions can byl phosphonium halide dissolved in a lower alkanol 30 be carried out in a batch, semi-continuous or continuous with an ion-exchange resin (quaternary ammonium hy process.