Styrene polymerization by ziegler‐natta catalysts based on bis(salicylaldiminate)nickel(II) complexes and methyl aluminoxane

Abstract

The homopolymerization of styrene by using different catalytic systems based on bis(salicylaldiminate)nickel(II) and methylaluminoxane was investigated. In particular, the effect on catalyst activity and polymer characteristics by electron withdrawing groups located on the phenolic moiety was studied. The influence of the bulkiness of the substituents on the N‐aldimine ligand was also ascertained. Finally the catalytic performances were investigated as a function of the main reaction parameters, such as temperature, Al/Ni molar ratio and duration.

Review of catalytic systems and thermodynamics for the Guerbet condensation reaction and challenges for biomass valorization

“…The complexes showed good activity, but a black solid, probably consisting of Pd(0), was formed during the reaction. 5 The authors consider the possibility that the deactivation of the Pd catalysts, reported by Gregorio et al, 146 could be due to the lower temperature (120°C) applied in the reaction. Similar to the Pd precursors, Burk et al 92 noticed the formation of a heterogeneous phase when employing Rh complexes.…”

“…Homogeneous Ni, Ru, Rh and Pd complexes were also studied at higher temperatures (200°C) by Carlini and coworkers. 5,81 Using MeONa, Pd(0) and PdIJII) complexes showed remarkable activity for the production of isobutanol from methanol and n-propanol. The oxidation state of the palladium precursor appeared to be unimportant with respect to its activity.…”

“…[4][5][6] The Guerbet condensation of alcohols is an alternative one-step process for the production of these 2-alkyl alcohols, also referred to as Guerbet alcohols. This reaction is of growing importance in biomass conversion processes as it provides an efficient way for the upgrading of smaller alcohols to heavier branchedchain alcohols with a unique branching pattern.…”

“…93 Compared to the industrial synthesis process, in which propene is hydroformulated to butyraldehyde, followed by aldol condensation and subsequent hydrogenation, the Guerbet condensation of n-butanol provides a renewable pathway for the production of 2EH and other "plasticizer alcohols" from higher alcohols. 5 As for aldehydes and ketones produced in biomass conversion ( Fig. 1), they can either first be hydrogenated to alcohols or be coupled directly by aldol condensation, thereby skipping the first dehydrogenation step of the Guerbet reaction cascade.…”

“…For instance, the Guerbet selfcondensation of n-butanol produces 2-ethylhexanol (2EH), industrially the most important compound in the group of "plasticizer alcohols". 5,[90][91][92] It is mostly applied in the synthesis of polymer additives, e.g. as a phthalate ester in PVC applications, giving the polymer improved flexibility and durability.…”