Synthesis and Polymerization of Renewable 1,3‐Cyclohexadiene Using Metathesis, Isomerization, and Cascade Reactions with Late‐metal Catalysts

Abstract

Synthesis and subsequent polymerization of renewable 1,3-cyclohexadiene (1,3-CHD) from plant oils is reported via metathesis and isomerization reactions. The metathesis reaction required no plant oil purification, minimal catalyst loading, no organic solvents, and simple product recovery by distillation. After treating soybean oil with a ruthenium metathesis catalyst, the resulting 1,4-cyclohexadiene (1,4-CHD) was isomerized with RuHCl(CO)(PPh3)3. The isomerization reaction was conducted for 1 h in neat 1,4-CHD with [1,4-CHD]/[RuHCl(CO)(PPh3)3] ratios as high as 5000. The isomerization and subsequent polymerization of the renewable 1,3-CHD was examined as a two-step sequence and as a one-step cascade reaction. The polymerization was catalyzed with nickel(II)acetylacetonate/methaluminoxane in neat monomer, hydrogenated d-limonene, and toluene. The resulting polymers were characterized by FTIR, DSC, and TGA.

One‐pot Synthesis of 1,3‐Butadiene and 1,6‐Hexanediol Derivatives from Cyclopentadiene (CPD) via Tandem Olefin Metathesis Reactions

“…It should be noted that beside the expected reaction products BD , 12 and 2 , the formation of 3 was also considerable due to self‐metathesis of 2 or CPD oligomers (Scheme ). Although 3 has low activity in metathesis, it can be isomerized to 1,3‐cyclohexadiene ( 13 ), which readily goes to metathesis reaction with 4 giving an additional amount of 5 and tetradehydro‐1,8‐octanediol diacetate ( 14 ) (Scheme ).…”

Synthesis of Modified Polycaprolactams Obtained from Renewable Resources

“…One of these byproducts is 1,4‐cyclohexadiene, obtained by intermolecular ring closing metathesis of linolenic acid methyl ester (Figure ). The group of Mathers described a direct synthesis of renewable 1,4‐cyclohexadiene from plant oils via metathesis . This solvent free method needed no plant oil purification, less catalyst and only a distillation as purification step, which made this synthesis very easy and environmentally friendly.…”

How well can renewable resources mimic commodity monomers and polymers?

“…90,96 Recently, a renewable method for the synthesis and polymerization of 1,3-CHD was reported. 97 As shown in Figure 9, plant oils, such as soybean, corn, and canola oils, contain polyunsaturated triglycerides which will react with metathesis catalysts to produce 1,4-CHD. Monounsaturated triglycerides produced acyclic C 12 , C 15 , and C 18 isomers.…”