Lithium-ethylene diamine catalyst

O Grady et al. (12), used a high-surface sodium on alumina catalyst at 25° for the isomerization of 4-methylcyclohexene and observed the formation of the three methylcyclohexene isomers (C). 4-Methylcyclohexene has also been isomerized by Reggel et al. (4), using the lithium ethylene diamine system. In general the reaction of cyclenes and the mechanism thereof may be considered to be like that of alkenes. 

These catalysts require temperatures above 100° and usually 150-200° for reasonable rates. Alkylsodium compounds at their decomposition temperatures (50-90°) have also been used by Pines and Haag (9). Lithium reacted with ethylene diamine has also been reported by Reggel et al. (4) as a catalyst for this reaction. The homogeneous system thus formed seems to lower the temperature requirement to 100° (4), whereas the use of potassium amide in liquid ammonia requires 120° (S). Sodium reacted with ethylene diamine has been reported to be an ineffective catalyst (4)- The most active catalyst systems reported so far are high-surface alkali metals and activated-alumina supports. They are very effective at or near room temperature (10-12). 

Recent investigations have shown lithium to be a unique catalyst for the polymerization of diolefins to materials of definite and predictable structure, and to have an interesting potential as a direct reducing agent in solvents such as ammonia, amines of low molecular, and ethylene diamine. 

The unique feature about anionic polymerization of diene to produce homopolymer was that the microstructure of the homopolymer could be altered and changed at will to produce unique physical and chemical properties. These microstructural changes can be introduced before, after or during the polymerization. For example, chelating diamines, such as tetramethyl ethylene and diamine (TMEDA) (18), with the alkyl-lithium catalyst have been used to produce polymer with 80 1,2 addition products, while the use of dipiperidine ethane (DPE),with same catalyst has produced polybutadiene with 100 1,2 addition product. 

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