Synthetic biodegradable polyesters tend to undergo slow biodegradation under ambient natural conditions and, hence, have been rejected or even banned recently in ecofriendly applications. Here, we demonstrate the preparation of polyesters exhibiting enhanced biodegradability, which were generated through a combination of old controversial macromolecules and aggregate theories. H 3 PO 4 -catalyzed diacid/diol polycondensation afforded polyester chains bearing chain-end −CH 2 OP(O)(OH) 2 and inner-chain (−CH 2 O) 2 P(O)(OH) groups, which were subsequently treated with M(2-ethylhexanoate) 2 (M = Zn, Mg, Mn, and Ca) to form ionic aggregates of polyesters. The prepared ionic aggregates of polyesters, which were constructed with fertilizer ingredients (such as M 2+ and phosphate), exhibit much faster biodegradability than that of the conventional polyesters under controlled soil conditions at 25 °C, while displaying comparable or superior rheological and mechanical properties.
α-Olefin trimers are used at a bulk scale as top-tier lubricant base oils, with putative future applications as diesel fuels obtainable from renewable ethylene. α-Olefin trimers are conventionally obtained in the cationic oligomerization process, during which a range of n-mers are simultaneously generated alongside severe skeleton rearrangement. In this context, catalysts that can selectively convert α-olefin to its trimers are valuable. However, few examples have been reported. Herein, we report selective α-olefin trimerization catalysts constructed via the modification of the Chevron–Phillips ethylene trimerization catalytic system and avoiding the use of expensive activators, such as methylaluminoxane (MAO), B(C6F5)3, and [B(C6F5)4]− salt, despite the typical Chevron–Phillips system being inactive for α-olefin. A catalytic system Cr(acac)3/[2,5-Me2C4H2N–Al(iBu)3]−Na+/(iBu)3Al demonstrating high turnover numbers exceeding 10,000 (31 kg/g-Cr for 1-decene), generating trimers selectively without other higher or lower fractions, was developed, confirmed by simulated distillation gas chromatography analysis. The hypothesized η5-pyrrolide chromium active species was partially confirmed by the structure elucidation of [η5-Me2C4H2N–AlMe3]Cr(Me)[CH2C6H4(ortho-NMe2)-κ2 C,N]. The prepared 1-decene trimers (after hydrogenation) exhibited an advantageously higher viscosity index than the commercial product PAO-4.0 (128 vs 123). Fluids demonstrating similar lubricant characteristics to either the 1-decene trimers or PAO-4.0 were obtained by using a 1-octene/1-dodecene blend.
Grignard reagents featuring carbanion characteristics are mostly unreactive toward alkyl halides and require a catalyst for the coupling reaction. With the need to prepare p-(CH2CH)C6H4CH2CH2CH2Cl on a large scale, the coupling reaction of p-(CH2CH)C6H4MgCl with BrCH2CH2CH2Cl was attempted to screen the catalysts, and CuCN was determined to be the best catalyst affording the desired compound in 80% yield with no formation of Wurtz coupling side product CH2CHC6H4–C6H4CHCH2. The p-(CH2CH)C6H4Cu(CN)MgCl species was proposed as an intermediate based on the X-ray structure of PhCu(CN)Mg(THF)4Cl. p-ClC6H4MgCl did not react with sterically encumbered R3SiCl (R = n-Bu or n-octyl). However, the reaction took place with the addition of 3 mol % CuCN catalyst, affording the desired compound p-ClC6H4SiR3. The structures of p-(CH2CH)C6H4CH2CH2CH2MgCl and p-ClC6H4MgCl were also elucidated, which existed as an aggregate with MgCl2, suggesting that some portion of the Grignard reagents were possibly lost in the coupling reaction due to coprecipitation with the byproduct MgCl2. R3SiCl (R = n-Bu or n-octyl) was also prepared easily and economically with no formation of R4Si when SiCl4 was reacted with 4 equiv of RMgCl. Using the developed syntheses, [p-(CH2CH)C6H4CH2CH2CH2]2Zn and iPrN[P(C6H4-p-SiR3)2]2, which are potentially useful compounds for the production of PS-block-PO-block-PS and 1-octene, respectively, were efficiently synthesized with substantial cost reductions.
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