Preparation of Hydrocarbons

The methodology for preparation of hydrocarbon-soluble, dilithium initiators is generally based on the reaction of an aromatic divinyl precursor with two moles of butyUithium. Unfortunately, because of the tendency of organ olithium chain ends in hydrocarbon solution to associate and form electron-deficient dimeric, tetrameric, or hexameric aggregates (see Table 2) (33,38,44,67), attempts to prepare dilithium initiators in hydrocarbon media have generally resulted in the formation of insoluble, three-dimensionally associated species (34,66,68—72). These precipitates are not effective initiators because of their heterogeneous initiation reactions with monomers which tend to result in broader molecular weight distributions > 1.1)... 

Aliphatic hydrocarbons can be prepared by the reduction of the readily accessible ketones with amalgamated zinc and concentrated hydrochloric acid (Clemmensen method of reduction). This procedure is particularly valuable for the preparation of hydrocarbons with an odd number of carbon atoms where the Wurtz reaction cannot be applied with the higher hydrocarbons some secondary alcohol is produced, which must be removed by repeated distillation from sodium. 

A study is presented of the synthesis and properties of the novel synthetic zeolite omega. The synthesis variables and kinetics of formation are discussed, as well as the ion exchange, sorption, and thermal properties. By decomposition of imbibed tetra-methylammonium ions and exhaustive treatments of the zeolite with ammonium ions, a pure hydrogen form can be obtained which is a suitable substrate for the preparation of hydrocarbon conversion catalysts. Several catalysts were prepared and utilized to isomerize n-hexane, and to hydrocrack a heavy gas oil. 

The methodulogy for preparation of hydrocarbon-soluble, dilithium initiators is generally based nn the reaction of an aromatic divinyl precursor with two moles of butyllilhium,... 

Sodium metal was also used similarly by Fittig as reagent for the preparation of hydrocarbons by treating aiyl bromide or iodide in the presence of diy ether, thus ... 

A very useful method for the preparation of hydrocarbons, more especially of aliphatic hydrocarbons, consists in replacing the halogen atom of a halogen compound by an atom of hydrogen. 

For. the preparation of hydrocarbons it may replace sodium ill the Wnrtz-Fittig reaction ... 

Somewhat less direct procedures have also been recognized. In 1967, Corey and Glass described the preparation of hydrocarbon 138 and its conversion through hydroboration and oxidation to ketone 139 (Scheme 23).216 Subsequent Baeyer-... 

The classical reagent for this reduction is ethyl alcohol, which is oxidized to acetaldehyde in the reaction. This reagent is unsatisfactory for the preparation of hydrocarbons a simultaneous reaction occurs to give ethyl aryl ethers. 

A large number of hydrocarbons are obtained from such mixtures as natural gas, petroleum, and coal tar. It is very difficult for a beginner to isolate in the laboratory a pure hydrocarbon from such mixtures, because a distillate which boils within a range of 10° usually contains many hydrocarbons. The preparation of hydrocarbons in the laboratory serves to illustrate general principles of important reactions, and at the same time provides an introduction to the technics used in the preparation of organic compoxmds. 

PREPARATION OF HYDROCARBONS BY THE USE OF THE GRIGNARD REAGENT (Toluene from Ben l Chloride)... 

Introduction. Some of the general methods used for the preparation of hydrocarbons were illustrated in experiments 10 to 16. The present experiment is designed to study a nmnber of the characteristic reactions of hydrocarbons and differences in their rates of reaction towards the same reagent. The student should try to record the data of his observation after each test and later write the explanation and equations for each reaction. 

In the preparation of hydrocarbons an alkyl, aryl, or aralkyl halide is mixed with an excess of an aromatic hydrocarbon, and anhydrous aluminum chloride is added in small portions. The reagents must be free from moisture. If the reactants are not liquid or the reaction is very vigorous, a solvent is used. Benzene, nitrobenzene, carbon disulfide, or o-dichlorobenzene may be employed as solvents. When polyhalides are used, more than one molecule of the hydrocarbon may react. For example, benzene with chloroform yields triphenylmethane, and benzene with carbon tetrachloride gives triphenylmethyl chloride ... 

The amount of aluminum chloride used varies with the type of reaction. In the preparation of hydrocarbons the amount of aluminum chloride used varies from 0.2 to 0.3 moles for each mole of halogen compound reacted. In using acyl chlorides for the preparation of ketones the amount of aluminum chloride is about mole per mole, while with anhydrides two moles of the salt are used. Technical grades of aluminum chloride give as good results as the chemically pure substance. In many cases the granular lumpy commercial material is to be preferred to the pure colorless powder. The latter is far more hygroscopic and more difficult to handle, particularly when powdered. 

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