CS229066B1 - Method of preparing monomeric lithium adducts anto conjugated dienes - Google Patents

Description

The present invention relates to a process for the preparation of monorneric adducts of two lithium atoms per molecule, conjugated by the reaction of lithium and diene in an aliphatic ether environment.

The reaction of lithium with diene, eg 1,3-butadiene, can be schemetically expressed as follows:

nCH ₂ = CH-CH == CH ₂ + 2nOL ----> Li (CH ₂ -CH = CH-CH ₂ ) Li

2 2 2 O

Although the formation of a monormic adduct (n = 1) in a few percent yield was observed in 2,3-diethylbutadte, Ziegler has not yet found an effective method for its preparation, particularly useful for unsubstituted 1,3-butadiene. The main product of the Ziegler process and others is an undefined mixture of dimeric and oligomeric adducts. The aluminas are used as initiators in anionic polymerization.

According to known methods, the reaction is carried out by adding to the mixture of lithium, an ethereal solvent and, optionally, a catalyst (usually packaged) a large amount of diene at a single time. The outer oligomeric adducts are storage instable (decompose by reaction with ether) and often have the consistency of a sticky precipitate which makes it impossible. working up the reaction mixture, or possibly continuing the reaction.

The monommy adducts of Li to the conjugated dienes are prepared by reacting lithium metal and diene in the presence of a di-ether and a polycyclic aromatic catalyst with stirring by adding 0.002 to 0.2 to 1000 g of the ether. mole of polycyclic aromatic compound and 0.05 to 10 g of lithium atoms per polycyclic aromatic compound, then gradually added at a rate of at most 0.2 mol of diene / h up to a maximum of 1 mol of diene / mol of lithium while maintaining the reaction temperature in the range of -30 to +30 ° C. ·

It is particularly preferred to remove the precipitating product during the process. '. It is also advantageous to reduce the diene dosage by at least half or by interruption when the specific electrical conductivity of the reaction mixture rises above 5.0 .mu.m.s.cm.

The mono-adduct can be used directly to initiate the polymerization of the unsaturated compounds, or an ethereal solvent derived from the preparation of the adduct can be used. replace it with another solvent according to the specific polymerization requirements.

The steric catalyst solvent separated during decantation or filtration can be reused for further cycles of preparation of the monommen adduct. Monomm ™! the adducts do not substantially lose the organometallic content during storage at room temperature for several days.

Example!

In this example, butadiene was dosed with unregulated rhythmology. To a 1000 ml spherical flask equipped with a stirrer, thermometer, and electrodes to measure the electrical conductivity of the solution was charged 1,030 mmol of lithium in the form of chips of approximately 10 x 5 x 0.2 mm (sodium content 0.8% wt), 3.65 mmol oa? talmud 327 g of absolute dead-butyl tert-butyl ether.

The butadiene gas was then fed at an average rate of 170 mum / hr at 15 ° C maintained by cooling. The electrical conductivity of the solution used as an indicator of the instantaneous concentration of the organometallic in the liquid phase, after a sharp rise to about 50 / i. After the addition of 174 mmol of butadiene, a sticky precipitate began to precipitate, which precipitated the metal particles and zoomed out with the reaction mixture. The increments of alkali liters in the continuous liquid phase ranged around 0.1 mmo / g with 1 mamo / g of added butadiene (see Table).

Sas (h) Amount of butadiene dosed (mmol) Alkkaita liquid phase ^{(MNO ol} g '") Alkalinity increase in liquid phase ⁽ mmol. Li.mmol BTD ^- ') 0.5 82 0,028 0.11 1.0 174. 0,054 0.09 1.5 258 0,075 0.08

Example 1 and d 2

The procedure was identical to that described in Example 1, except that the butadiene was fed to the reaction mixture at an average rate of 13.2 m / h, while the maximum flow rate of the butadiene metered was operably controlled so that the specific conductivity of the solution exceeded 1. iS.cm. The concentration of organometallic in the liquid phase did not exceed the value of 0.02 mmol Li / g throughout the experiment. Thus, 327 mmol of butadiene were metered into the reaction mixture without significant formation of tacky products. The dilitboobuted suspension obtained had an activity of 97.0% (by double titration according to Gilman and allyHoomide as an organometallic slag) and an alkalinity of 1.46 mmo / g corresponding to a yield of 77%. % on butadiene.

Deevitization. trio-ethylsilyl chloro-video, followed by gas chromatographic analysis and 1 H-NMR spectroscopy showed that 1,4-lithithiobutet was obtained in a purity of better than 99%. The activity decreased during one month of storage - at 25 to 94.5. The product was an effective itoneo in polymorphation of butadiene to MI = 2000.

Example 3

The procedure was the same as that described in Example 1 except that isoprene was used instead of adadiene. dosed into the reaction mixture at an average rate of 15.6 mmo / h at 17 ° C, the rate of dosing was controlled so that the specific conductivity of the mixture was not greater than 1.5 <uS.om, respectively, so that the concentration of organometallic in the liquid phase did not exceed 0.03 moml Li / g.

Thus, 241 of isoprene were metered into the reaction mixture without significant formation of tacky products. The resulting dilithomethylbutet suspension had a reactivity of 97.1% and an alkalinity of 1.15 mmol Li / g, which corresponds to a yield of isoprene of 81.8%. on the MM - 600.

Example 4

11 mol of lithium in the form of shavings, 3,160 g. While stirring, the butadiene was then introduced into the flask above the level of the reaction mixture at 14 ° C at a rate of 300 mmo / h ^; in total 1 mol. At this rate of addition, the amount of feed was not yet live. to form a door (soluble) and oligomeric (tacky) adduct.

After the addition of butadiene was complete, the reaction mixture was stirred for 15 minutes and then the suspension was separated from excess lithium by decubation and allowed to stand for 3 hours. During this time, the violet layer of the clear supernatant (solvent with catalyst) separated and was pushed back into the reaction flask to excess lithium. The reaction flask was then charged with o-ethyl-tert-butyl ether (1300 g) and packed onto the original liquid and the addition of butadiene was repeated.

Five batches were thus treated, after which a mole of lithium was added to the reaction mixture after the third batch. The amount of the suspension obtained and its alkalinity corresponded to the yield of 1,4-dilithiobutene (monomer adduct) 83.9, 72.7, 69.9, 84.0 and 75.5. The activity was 90-> 4 as determined by double titration according to Gilman 8 with allyl bromide as a stripper. organometallic. During storage at 23 ° C for seven days, activity decreased to 95.1%.

Claims (3)

A process for the preparation of monomeric lithium adducts to co-induced dienes by reacting lithium metal with diene in the presence of an aliphatic ether and a polycyclic aromatic compound catalyst with stirring, characterized in that 0.002 to 0.2 mol of polycyclic is added to 1000 g of aliphatic ether. aromatic compounds with 0.05-10 g of lithium atoms per polycyclic aromatic compound, followed by the addition of a member at a rate of at most 0.2 moles of diene / h up to a maximum of 1 mol of diene / mol of lithium, maintaining the reaction temperature to +30 ° C. 2. Process according to claim 1, characterized in that during the process the precipitated product is removed. 3. A process according to claim 1 or 2, characterized in that the diene dosage is reduced by at least half or even interrupted when the specific electrical capacity of the reaction mixture rises above 5.0 .mu.m.s.cm.