T h e literature related to simple urlsubstituted F i n y l allq 1 ethers is reviewed. New data are presented on the purification and properties of the vinyl alkyl ether monomers. Special attention is given to vinyl methyl, vinyl n-butJ 1, and vinyl isobutyl ethers, which have been made available for dekelopment purposes in this country by application o f the Reppe synthesis. Correct physical data on these materials are of special interest both because, the monomers are com-HIS paper discusses simple compounds of the type T CH2=CHOR, where R is an alkyl group free from unsaturation and both the vinyl and R groups are free from halogen or other substitution. Vinyl methyl ether, vinyl n-butyl ether, and vinyl isobutyl ether are the members of the series which received most attention and whose polymers are discussed.The nex data presented from this laboratory comprise the major part of the material under the headings Purification, Physical Properties, and Polymerization, as well as Properties and Stabilization of the Polymers. B large part of the information on

INTRODUCTIONReliable phase equilibrium data are essential for the design of effective and economical gas treatment processes such as natural gas liquefaction. Data on cryogenic mixtures involving relatively simple molecules are also of theoretical interest. An apparatus and the techniques developed to obtain solid-liquid phase equilibrium data for cryogenic systems are described here. Results are presented for the individual solubilities of solid benzene, toluene, n-hexane, and n-heptane in liquid methane.There are basically two ways to obtain solubility data: the isoplethal method or the isothermal method. The isoplethal method, in which mixtures of known composition are subjected to temperature changes, is not widely used when the solubility is very low. The early work of Stackelberg et al. [1] and the more recent work of Heastie and Lefebvre [2] and Yunker and Halsey [3] are representative of this approach.The use of gas chromatography, which allows the accurate and convenient analysis of vaporized fluid mixtures, has favored increased application of the isothermal or analytical method. Two steps are important in the isothermal method: making the solution and the sampling of this solution for analysis. A usual technique of preparing the solution is to agitate the mixture in the presence of excess solute by mechanical stirring or recirculation of the vapor phase. Jensen and Kurata [4] and Neumann and Mann [5] used the former, while Preston et al. [6] used the recirculation technique. Failure to promote equilibration by agitation can result in systematic errors, as found in the data of Fedorova [']. Solutions can also be formed using a single-pass mode either with solute precipitating from a feed mixture or a previously deposited solute dissolved into a pure solvent feed. Cheung and Zander [8] used the first techni'lue and both techniques have been used in solid-vapor equilibrium measurements ["]. The resultant solution can be flash-evaporated directly to ambient temperature [4.6.8] or the solution can be transferred to a separate chamber and the entire apparatus warmed to ambient temperature [5.'].Discrete samples taken from a bulk solution tend to be poorly reproducible, especially in the parts per million concentration range. Also, the presence of minute quantities of highly soluble contaminants in the solute material can interfere with analysis by gas chromatography. A major advantage of the continuously flowing sample stream is that it attains steady state with respect to adsorption effects in the

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