Methyl methacrylate purification

One of the most important appHcations of this process is that of methyl methacrylate manufacture. In this process (81), acetone cyanohydrin is treated with sulfuric acid at 100°C, affording the corresponding methacrylamide sulfate which is esterified with methanol. After purification, methyl methacrylate (99.8% purity) is obtained in a yield of ca 85%. 

Materials and Purifications. 2-Methyl pentene-1 (Aldrich) was distilled under normal pressure at 62°C after refluxing for one hour 1n the presence of A1L1H.. Methyl methacrylate and para-methyl styrene (Aldrich) were distilled under reduced pressure at about 60°C the purified monomers were sealed and stored 1n refrigerator before use. The compressed gas, sulfur dioxide (Matheson), was led through a P208 tower before Introduced Into reaction system. Hydroxyethyl acrylate (Aldrich) was used for polymerization without further purification. 

Laboratory reagent grade methyl methacrylate monomer was dried over powdered calcium hydride and freshly distilled before use. The checkers found that identical yields could be obtained when Matheson Coleman and Bell Chromatoquality methyl methacrylate monomer was used as received with no purification. 

Materials. Methyl methacrylate (MMA) and methacrylic acid (MAA) monomers (Rohm and Haas), and n-dodecyl mercapten (Eastman Kodak Co.) were purified by vacuum distillation under nitrogen atmosphere to remove the inhibitor. Distilled-deionized and deoxygenated water was used in all polymerizations. Sodium lauryl sulfate (99% Onyx Maprofix 563) and Triton X-100 nonionic surfactant (Rohm and Haas), and potassium persulfate initiator (Fisher Scientific Co.) were used as received without further purification. 

Chemicals. Reagent grade chemicals were used in the study of grafting. Acetone, ethyl alcohol and benzene were redistilled before use. Monomer, methyl methacrylate (MMA), was used fresh after purification and distillation. It was purified following the method adopted by Gupta and Nandy (15). CAS was used after standardization by an usual method (16). All CAS solutions used for the study was acidified with 1% H2SO4. 

Materials. Cellulose and cellulose derivatives used for this study are summarized in Table 1. Commercial products were used as received without further purifications. Methyl methacrylate was used as the monomer, which was purified by sodium hydroxide/sodium chloride extraction followed by distillation under reduced pressure (10). 

Purification of methyl methacrylate by distillation in a series of three columns operating under vacuum and in the presence of a polymerization inhibitor. The first (— 25 trays) removes the light products (dimethyl ether, water, eta). The second (25 to 30 trays) produces the ester to commercial specifications by removing the heavy products, from which the methacrylate contained is recovered in the last column, and recycled to the previous one. 

Reagents were obtained from Aldrich Chemicals, The Netherlands, and were used as supplied commercially without further purification. Dihydroxybenzoic acid (DHB) was used as the matrix. In inlet A, 0.3 pL of polystyrene (PS MWav = 3500Da) in tetrahydrofuran (THF)/water was injected with DHB as the matrix. In inlet B, 0.3 pL of poly(methyl methacrylate) (PMMA MW = 3500 Da) in THF/water was injected with DHB as matrix. 

Materials. VEC was prepared by the catalyzed addition of CO2 to 3,4-epoxy-l-butene using conditions typical of that used industrially [77], then purified by vacuum distillation. Other raw materials were used as received without any additional purification. Mixed xylenes, vinyl acetate (VA), butyl acrylate (BA), butyl methacrylate (BMA), methyl methacrylate (MMA), styrene (St), and t-butyl hydroperoxide were obtained from Aldrich Chemical Company. Lupersol 575 (t-amyl peroxy (2-ethylhexanoate)) was supplied by Elf Atochem. Vazo 67 (2,2 -azobis(2-methylbutyronitrile)) was obtained from DuPont Chemical Company. Vinyl pivalate (NE05), vinyl 2-ethylhexanoate (V2EH), Tergitol NP-40 (non-ionic surfactant) and QP-300 (hydroxy ethyl cellulose) were obtained from Union Carbide Coq)oration. Aerosol OT-75 (surfactant) was obtained from Cytec. Sodium formaldehyde sulfoxylate was obtained from Henkel Corporation. Ethyl 3-ethoxy propionate (EEP), propylene glycol monomethyl ether (PM) and PM acetate (PM Ac) are Eastman Chemical Company products. 

A few monomers, like styrene and methyl methaciylate, will, after careful purification and presumably free from all impurities, polymerize at elevated temperatures. It is supposed that some ring-substituted styrenes act similarly. The rates of such thermal self-initiated polymerizations are slower than those carried out with the aid of initiators. Styrene, for instance, polymerizes only at a rate of 0.1 % per hour at 60 C, and only 14% at 127 C. The rate of thermal polymerization of methyl methacrylate is only about 1% of the rate for styrene.Several mechanisms of initiation were proposed earlier. The subject was reviewed critically. More recently, the initiation mechanism for styrene polymerization was shown by ultraviolet spectroscopy to consist of an initial formation of a Diels-Alder dimer. The dimer is believed to subsequently transfer a hydrogen to a styrene molecule and form a free radical ... 

Materials. Synthesis of 1,2,3,4-tetrahydro-l-naphthylideneamino p-styrenesulfonate (NIS) was reported in detail elsewhere (6). Methyltriethoxysilane (MTEOS), tetramethoxysilane (TMOS), tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMOS) were of reagent grade and used without further purification. Methyl methacrylate (MMA), N,N-dimethylaciylamide (DMAA), acryloylmorpholine (AMO), and tetrahydrofurfuryl methacrylate (THFMA) were distilled before use. 

XAD-8 is a nonionic, macroporous (pore size 25 pm), methyl methacrylate ester resin. Because it is sometimes difficult to obtain, it may be necessary to use an alternative resin such as Polyclar, which is a cross-linked poly(vinylpyrrolidone). Extensive purification of the resins is always required before use. 

The copolymers were synthesized by radical initiated copolymerization of methacrylate monomers in butanone under inert conditions (dry nitrogen atmosphere). As initiator 2,2 -azobis-(2-methyl propionitrile) (AIBN) was employed. The copolymers obtained were used without further purification. The following example to produce the copolymer poly [methyl methacrylate-co-Zonyl TM-co-2-(methacryloyloxy)ethyl acetoacetate] (Table 1, polymer 21b) from three monomers illustrates the typical synthesis ... 

Methyl methacrylate (MMA) was purified by distilling twice vacuo over CaH. Further purification was carried out by distillation in vacuo onto a sodium mirror, followed by distillation into ampoules equipped with breakseals. 

---