DE263017C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

263017 CLASS 12 or GROUP

Patented in the German Empire from June 1, 1912.

It has been found that the normal pentenes by heating to higher temperatures, especially in the presence of catalysts, convert to isomeric olefins, especially trimethylethylene, let convert. With intermolecular rearrangement, the normal hydrocarbons are formed those with a branched carbon chain.

Since the pentenes, ζ. B. from the in the low-boiling Fractions of petroleum in large quantities of normal pentane, easily accessible are, the present process is a convenient way to represent the technically important isopentene (trimethylethylene) represent.

Instead of the normal pentenes, it is also possible to use compounds that are included in the Conditions pass into this, such as B. halogenated normal pentanes, pentyl alcohols

and the like.

From the investigations of Ipatiev about "Pyrogenetic contact reactions of organic compounds" (reports from the D. former Society 36/1903, pp. 2003 and ff.) It is known that the isopropylethylene when passing over heated aluminum oxide undergoes extensive conversion into trimethylethylene; it acts. In this contact isomerization, however, there is only a shift in the double formation, without a change in the carbon structure taking place at the same time as in the present process.

Example 1.

1065 parts by weight of monochloro normal pentane, produced by chlorinating a gasoline fraction with a boiling point of 36 to 38 °, are passed over 2000 parts by weight of powdered quicklime at 385 to 400 °; the vapors of the resulting n-pentenes are passed without previous condensation through annealed and heated to about 450 ⁰ alumina. If necessary, especially at the beginning, the temperature can be lowered a little. The product obtained by good cooling has a boiling point of 34 to 38 °. About 650 to 700 parts of this product are obtained, about half of which consists of trimethylethylene.

If you want to represent the isopentene in pure form, you can use more concentrated Shake out aqueous hydrochloric acid, with the trimethylethylene in the boiling at 84 to 86 ° Isoamyl chloride is converted, and this from unchanged n-pentene and possibly Separate small amounts of isopropylethylene by distillation, which either further can be passed separately or anew over annealed alumina.

By splitting off the hydrochloric acid again from the chloride, a temperature of 34 to 36 ° is obtained boiling isopentene.

If the hexylenes obtainable from monochloro-n-hexane are used instead of n-pentene

at 400 ° over calcined aluminum oxide, a distillate is obtained in a likewise almost quantitative yield, which in the treatment with concentrated aqueous hydrochloric acid one boiling at 110 to 115 °, predominantly from 2-chloro-2-ethylbutane

CH ^ C

C Mn · C Mn

C Mn · C M o

Cl

existing monochloride supplies.

Example 2.

86 parts of methyl n-propyl ketone by boiling Ethylacetessigester, with 100 parts sodium hydroxide solution of 30 percent and 250 parts of ether mixed together. 50 parts of sodium are gradually added with stirring and at the same time allows 200 parts of water to run in slowly. One receives on this Way the corresponding alcohol from boiling point 115 to 117 °. One directs the alcohol over clay heated to 450 to 475 ° and processes the distillate if desired for the purpose of pure preparation of the isopentene formed as in Example 1.

Claims (1)

Pate nt-An SPRU cn: Process for the preparation of isopentenes and their derivatives from normal pentenes and their derivatives, consisting in that one normal pentenes or their derivatives or compounds included under the coming conditions pass into this, expediently heated to a higher temperature in the presence of catalysts.