DE927873C - Process for the preparation of sodium cyclopentadiene, sodium alkyl and sodium benzyl cyclopentadienes - Google Patents

Description

ISSUED MAY 20, 1955

Z 2857 IVc j 12 ο

In the patent 924029 it was shown that in the same way as that already by Johannes Thiele discovered cyclopentadiene potassium, the cyclopentadiene sodium from cyclopentadiene or its dine forms and metallic sodium or compounds that release sodium slightly Formula NaX, in which X stands for H, alkyl, aryl, indenyl,

Fluorenyl, NH ₂ , NH-aryl,

stands here-

can be made, in an inert solvent such as a hydrocarbon. Essential for the quantitative progress of the reaction is a fine distribution of the sodium metal, or compounds of the formula NaX, and a reaction temperature up to 250 °, preferably between 60 and 200 such ^0th

In addition to this, it has now been found that sodium cyclopentadiene can also be produced with particular advantage in liquid ammonia as a solvent. You can work above -33 ⁰ , the boiling point of ammonia, in an autoclave or at a lower temperature in an open vessel (but with the exclusion of air). Initially, solutions of cyclopentadiene sodium are formed, which can contain more sodium cyclopentadiene at -33 ° to 20% or even more at higher temperatures.

This is one for the further use of the sodium cyclopentadiene for synthetic purposes a particularly valuable advantage of the process according to the invention, since there has been no solvent for sodium cyclopentadiene to date was known and the sodium cyclopentadiene, of course, lighter in solution

reacts than in the solid, even if it is finely divided State. The good solubility in liquid ammonia has been found to be specific Property of sodium cyclopentadiene; the like Li, K, Ca, Sr, Ba compounds are on the other hand, all of them are very difficult to dissolve in ammonia. The solid sodium cyclopentadiene can be extracted from the solutions Easily obtainable, in a particularly pure, completely colorless form.

ίο As opposed to cyclopentadiene in its behavior Sodium corresponds more to styrene, as in a work by Sch lenk (Liebigs Annalen der Chemie, Vol. 463, p. 60, last line, and p. 61, lines 1 to 3) and for example Styrene in the presence of sodium and many sodium compounds in ether as a solvent, polymerized in concentrated form or dissolved in liquid ammonia in the presence of sodium amide, one also had to oppose the cyclopentadiene in the solution in liquid ammonia Sodium amide or sodium metal and other sodium compounds with the onset of polymerization calculate. According to the state of the art described, it was by no means a matter of course that one from cyclopentadiene in liquid ammonia by the action of sodium metal or compounds which give off sodium easily obtain the sodium compound of cyclopentadiene would; because if for a hydrocarbon there is a risk of polymerisation on contact with Sodium or with reactive compounds is given at all, then this danger also exists in liquid ammonia as a solvent, as described for styrene.

Example χ

23 g sodium metal (1 gram atom) are dissolved with stirring in 500 cc of liquid ammonia at -40 ^0th In the deep blue solution is allowed 96 g (1.5 mol) of monomeric cyclopentadiene also with further stirring at - 35 to - 40 ⁰ 'is added dropwise. When all of the sodium has reacted with cyclopentadiene to form cyclopentadiene sodium, the blue color of the solution immediately disappears. The ammonia is then evaporated off by slowly heating the reaction vessel.

A colorless to pale yellowish colored, finely crystalline powder is obtained which dissolves in air immediately turns brown-black and inflamed.

The yield of cyclopentadiene sodium is quantitative. It does not contain a trace of sodium metal. By Any desired suspension can be produced by adding it to any inert solvent.

Example2

In a 5 l steel autoclave with magnetic stirring, 31 liquid NH _{3 is} condensed onto 161 g of sodium metal (7 gram atoms), in which the sodium dissolves completely with stirring. With an injection pump, 990 g of monomeric cyclopentadiene are injected within 30 minutes. The occurrence of a temperature increase and an increase in pressure indicate that the reaction has started. After the reaction has ended, the stirred autoclave is heated up and the ammonia is driven over by means of a steel capillary into a second steel autoclave which is kept at room temperature or lower. Most of the ammonia is removed from the reaction autoclave in the course of a few hours. The last traces can be blown off in a stream of nitrogen. The majority of the ammonia is now in the second autoclave, in which the reaction can be carried out again. The sodium cyclopentadiene is suspended in inert organic solvents with the exclusion of air, whereupon it is accessible for further reactions.

Example3

39 g of finely powdered sodium amide (1 mol) are added at -40 ⁰ in 500 cc of liquid ammonia. In the fine suspension is allowed with stirring 66 g (1 mol) of monomeric cyclopentadiene also at - 35 to - 40 ⁰ dropwise. When all of the sodium amide has reacted with the cyclopentadiene to form cyclopentadiene sodium, a colorless solution is obtained from which the cyclopentadiene sodium is obtained in solid form after the ammonia has been evaporated off.

Claims (2)

PATENT CLAIM: Process for the production of sodium cyclopentadiene, Sodium alkyl and sodium benzylcyclopentadienes by reacting Sodium metal or sodium compounds with cyclopentadiene that release sodium easily, Alkyl or benzylcyclopentadienes according to Patent 924 029, characterized in that the reaction is carried out in liquid ammonia as a solvent. Referred publications: R e m y, Textbook of Inorganic Chemistry, 4th and 5th ed., 1949, Vol. 2, p. 699, para. 2 of below, p. 701, para. 2. 1 509 504 5.