Other than their established short-chain congeners, polycondensates based on long-chain difunctional monomers are often dominated by the long methylene sequences of the repeat units in their solid-state structures and properties. This places them between traditional polycondensates and polyethylenes. The availability of long chain monomers as a key prerequisite has benefited much from advances in the catalytic conversion of plant oils, via biotechnological and purely chemical approaches, likewise. This has promoted studies of, among others, applications-relevant properties. A comprehensive account is given of long-chain monomer syntheses and the preparation and physical properties, morphologies, mechanical behavior, and degradability of long chain polyester, polyamides, polyurethanes, polyureas, polyacetals, and polycarbonates.

Acetal metathesis copolymerization (AMCP) of renewable isohexide diacetals and aliphatic long-chain diacetals is reported and access to a small family of copolyacetals has been established. Crucial 1–2D NMR and MALDI-ToF-MS findings unambiguously confirm the existence of a copolymeric structure. In a stark contrast to the earlier reported isohexide-polyacetals, the current copolyacetals reveal very slow degradation. Hydrolytic degradation of copolyacetal pellets is extremely slow at pH 7, whereas only 30% degradation over a period of 15 d is observed in 9 m hydrochloric acid solution. GPC investigations reveal that with increasing chain-length the rate of degradation reduces, whereas copolyacetals with short-chain aliphatic segments display a faster degradation profile. The reduced rate of degradation can be attributed to the hydrophobic nature of long-chain acetal segments. In situ NMR spectroscopy reveals the existence of formates, hemiacetals, and diols as degradation products. Thus, the rate of degradation can be tuned by the judicious choice of isohexide-diacetal and linear-diacetals in a copolyacetal.

alpha,omega-Difunctionalized long-chain compounds A-(CH2)(n)-B are valuable intermediates and monomers. Unsymmetrical compounds with two different functional groups (A not equal B) are, however, only accessible by multistep traditional organic syntheses to date. We report on their generation in a single step by isomerizing alkoxycarbonylations of the double bond deep in the chain of oleic derivatives. The compatibility with amide, nitrite and imide functionalities in the substrate allows for the formation with high linear selectivities (ca. 90%) and conversions (70 to 96%) of unsymmetric diesters, ester-amides, ester-nitriles and ester-(N-imides) in which these functional groups are terminally attached to a >= 17 methylene unit chain. These products further provide access to carboxylic acid-esters, alcohol-esters and amino-esters, and polymers from these AB-monomers. Undesired transesterifications that scramble the A and B functionalities are suppressed completely (<0.1%) by the utilization of a Pd(II) catalyst precursor devoid of acid additives in the presence of amine base.

Thermoplastic polyester elastomers prepared from a plant-oil derived crystallizable long-chain aliphatic α,ω-dicarboxylic acid have been investigated.

The 1,2-(CH2P(1-adamantyl)(2))(2)C6H4 (dadpx) coordinated palladium complex [(dadpx)Pd(OTf)(2)] (1) is a catalyst precursor for the isomerizing methoxycarbonylation of the internal double bond of methyl oleate, with an unprecedented selectivity (96%) for the linear diester 1,19-dimethyl nonadecanedioate. Rapid formation of the catalytically active solvent-coordinated hydride species [(dadpx)PdH(MeOH)](+) (3-MeOH) is evidenced by NMR spectroscopy, and further isolation and X-ray crystal structure analysis of [(dadpx)PdH(PPh3)](+) (3-PPh3). DFT calculations of key steps of the catalytic cycle unravel methanolysis as the decisive step for enhanced selectivity and the influence of the rigid adamantyl framework on this step by destabilization of transition states of unselective pathways.

Current efforts to technically use microalgae focus on the generation of fuels with a molecular structure identical to crude oil based products. Here we suggest a different approach for the utilization of algae by translating the unique molecular structures of algae oil fatty acids into higher value chemical intermediates and materials. A crude extract from a microalga, the diatom Phaeodactylum tricornutum, was obtained as a multicomponent mixture containing amongst others unsaturated fatty acid (16:1, 18:1, and 20:5) phosphocholine triglycerides. Exposure of this crude algae oil to CO and methanol with the known catalyst precursor [{1,2-(tBu2 PCH2)2C6H4}Pd(OTf)](OTf) resulted in isomerization/methoxycarbonylation of the unsaturated fatty acids into a mixture of linear 1,17- and 1,19-diesters in high purity (>99 %). Polycondensation with a mixture of the corresponding diols yielded a novel mixed polyester-17/19.17/19 with an advantageously high melting and crystallization temperature.

The polycondensation of long-chain α,ω-diesters with long-chain α,ω-diols, prepared by means of catalytic conversion of plant oils, affords linear aliphatic polyesters. They contain both long crystallizable polyethylene-like hydrocarbon segments and ester moieties in the backbone. In a convenient catalytic one-step process a high-purity polycondensation grade dimethyl-1,19-nonadecanedioate monomer is obtained directly from the technical grade methyl ester of high oleic sunflower oil. Likewise, dimethyl-1,23-tricosanedioate is derived from methyl erucate. The successful scale-up renders both intermediates available on a 100 g scale. Injection molded parts of polyester-19.19 and -23.23 with a number average molecular mass of Mn = 3 × 104 g mol−1 possess an elongation at break of >600% and a Young's modulus of 400 MPa. Electrospinning produces non-woven meshes. The polyesters prepared even enable film extrusion and represent new blend components for a variety of thermoplastics including polyethylene.

Selective catalytic carbonylation of the trisubstituted double bond of citronellic acid is enabled via an isomerization–functionalization approach. Alkoxycarbonylation with [{1,2-(tBu2PCH2)2C6H4}Pd(OTf)2] as a catalyst precursor occurs with >97% selectivity for the terminal diester dimethyl-3,7-dimethylnonane-dioate. This prevails much over the typical cationic methoxyaddition. The reactive primary carboxy group formed allows for e.g. the preparation of the high molecular weight novel polyester poly[3,7-dimethylnonanediyl-3,7-dimethylnonanedioate].

The synthesis of unsymmetrical diphosphine ligands (3a-g) with an o-tolyl backbone and tert-butyl, adamantyl, cyclohexyl and isopropyl substituents on the phosphorus moiety is described (1,2-(CH2PR2)(PR'2)C6H4; 3a: R=tBu, R'=tBu, 3b: R=tBu, R'=Cy, 3c: R=tBu, R'=iPr, 3d: R=Ad, R'=tBu, 3e: R=Ad, R'=Cy, 3f: R=Cy, R'=Cy, 3g: R=Ad, R'=Ad). The corresponding diphosphine-Pd(II) ditriflate complexes [(P^P)Pd(OTf)2] (5a-g) were prepared and structurally characterised by X-ray crystallography. These new complexes were studied as catalyst precursors in the isomerising methoxycarbonylation of methyl oleate, and were found to convert methyl oleate into the corresponding linear α,ω-diester (L) with 70-80% selectivity. The products of this catalytic reaction with the known [{1,2-(tBu2PCH2)2C6H4}Pd(OTf)2] complex (5h) were fully analysed, and revealed the formation of the linear α,ω-diester (L, 89.0%), the methyl-branched diester B1 (4.3%), the ethyl-branched diester B2 (1.0%), the propyl-branched diester B3 (0.6%) and all diesters from butyl- to hexadecyl-branched diesters B4-B16 (overall 4.8%) at 90 °C and 20 bar CO. The productivity of the catalytic conversion of methyl oleate with complexes 5a-g varied with the steric bulk of the alkyl substituent on the phosphorus. Ligands with more bulky groups, like tert-butyl or adamantyl (e.g., 5a, 5d, 5g), were more productive systems. The formation of the catalytically active hydride species [(P^P)Pd(H)(MeOH)](+) (6-MeOH) was investigated and observed directly for complexes 5a-e and 5g, respectively. These hydride species were isolated as the corresponding triphenylphosphine complexes (6-PPh3) and fully characterised, including by X-ray crystallography. The catalytic productivity of 6a-PPh3 was virtually identical to that of 5a, thereby confirming the efficient hydride formation of 5a under catalytic conditions.

Plant oils with their long linear methylene sequences are attractive substrates for polymeric materials, such as long-chain aliphatic polyesters and polyamides. Existing biotechnological routes for their conversion to long-chain linear alpha,omega-dicarboxylic acid derivatives have recently been complemented by chemical catalytic conversions. This contribution discusses and compares the conversion of unsaturated fatty acids by olefin metathesis and by isomerizing alkoxycarbonylation, and reviews properties of resulting long-chain aliphatic polyesters. The impact of multiple unsaturated fatty acids present in technical grade plant oils is adressed.

Self-metathesis of erucic acid by [(PCy(3))(η-C-C(3)H(4)N(2)Mes(2))Cl(2)Ru = CHPh] (Grubbs second- generation catalyst) followed by catalytic hydrogenation and purification via the ester yields 1,26-hexacosanedioate (>99% purity). Polyesterification with 1,26-hexacosanediol, generated from the diester, affords polyester-26,26, which features a T(m) of 114 °C (T(c) = 92 °C, ΔH(m) = 160 J g(-1)). Ultralong-chain model polyesters-38,23 (T(m) = 109 °C) and -44,23 (T(m) = 111 °C), generated via multistep procedures including acyclic diene metathesis polymerization, underline that melting points of such aliphatic polyesters do not gradually increase with methylene sequence chain length. Available data suggest that to mimic linear polyethylenes thermal properties, even longer sequences, amounting to at least four times a fatty acid chain, fully incorporated in a linear fashion are required.

Plant oil-derived α,ω-diacetals are polycondensated to the novel polyacetals [OCH(2) O(CH(2))(y)](n) (y = 19 and 23) with molecular weight of ca. M(n) = 2 × 10(4) g mol(-1). The long methylene sequences provide substantial melt and crystallization temperatures (T(m) = 88 °C and T(c) = 68 °C for y = 23), and rates of hydrolytic degradation are dramatically lower for the long-chain polyacetals versus a shorter chain analogue (y = 12) studied for comparison.

Front Cover: Polycondensation of α,ω-diacetals derived from plant oils yields long-chain polyacetals. These novel materials are water-degradable, with degradation rates strongly depending on the chain-length of the repeat units. Further details can be found in the article by S. Chikkali, F. Stempfle, and S. Mecking* on page 1126.

Isomerizing alkoxycarbonylation of methyl oleate and ethyl erucate, respectively, yielded dimethyl 1,19-nonadecanedioate and diethyl 1,23-tricosanedioate in >99% purity. With [kappa(2)-((P) over cap P)Pd(OTf)][OTf] as a defined catalyst precursor ((P) over capP = 1,2-bis[(di-tert-butylphosphino)methyl]benzene) the reaction can be carried out without the need for additional added diphosphine. Saponification of the diesters yielded 1,19-nonadecanedicarboxylic acid and 1,23-tricosanedicarboxylic acid in >99% purity. By ruthenium-catalyzed reduction of the diesters with H-2, 1,19-nonadecanediole and 1,23-tricosanediole were formed in high yield and purity (>99%). From the latter, 1,19-nonadecanediamine and 1,23-tricosanediamine were generated. Polyesters with commercially available shorter-chain petrochemical or renewable diols exhibit high melting points due to the crystallizable long-chain methylene segments from the dicarboxylic acid component, e.g., poly[1,6-hexadiyl-1,23-tricosanedioate] T-m 92, T-c 75 degrees C. Thermal properties of novel long-chain polyamides are reported.