Catalyst stannous 2-ethylhexanoate

Two different mechanisms have been proposed for the ROP of (di)lactones depending on the nature of the organometalhc derivatives. Metal halides, oxides, and carboxylates would act as Lewis acid catalysts in an ROP actually initiated with a hydroxyl-containing compound, such as water, alcohol, or co-hydroxy acid the later would result more hkely from the in-situ hydrolysis of the (di)lac-tone [11]. Polymerization is assumed to proceed through an insertion mechanism, the details of which depends on the metal compound (Scheme la). The most frequently encountered Lewis acid catalyst is undoubtedly the stannous 2-ethylhexanoate, currently referred to as stannous octoate (Sn(Oct)2). On the other hand, when metal alkoxides containing free p-, d-, or f- orbitals of a favo-... 

The methanolysis catalyst is generally a base such as potassium carbonate, since the base catalyzed transesterification is generally lower in energy(5). For the transesterification of the hydroxymethylated fatty esters, however, a Lewis acid (stannous 2-ethylhexanoate) is employed. Although this catalyst requires higher temperatures to achieve rapid equilibrium, it has the benefit of not requiring removal... 

A similar method has been reported by Albertsson et al. [290], in which equimolar amounts of propane-1,3-diol and DEC were used, with stannous 2-ethylhexanoate as the transesterification catalyst, affording a yield of 53%. 

Synthetic routes include anionic, cationic, zwitterionic, and coordination polymerization. A wide range of organometallic compounds has been proven as effective initiators/catalysts for ROP of lactones Lewis acids (e.g., A1C13, BF3, and ZnCl2) [150], alkali metal compounds [160], organozinc compounds [161], tin compounds of which stannous octoate [also referred to as stannous-2-ethylhexanoate or tin(II) octoate] is the most well known [162-164], organo-acid rare earth compounds such as lanthanide complexes [165-168], and aluminum alkoxides [169]. Stannous-2-ethylhexanoate is one of the most extensively used initiators for the coordination polymerization of biomaterials, thanks to the ease of polymerization and because it has been approved by the FDA [170]. 

Two sets of networks were prepared. In the first network, the M of the short chains was 660 g/mol (660-21.3 X 10 ), and in the second network, it was 880 g/ mol (880-21.3 X 10 ). The compositions of the networks are given in Table I. The chains were end linked with tetraethoxysilane, with stannous 2-ethylhexanoate as catalyst. The reactions were carried out for 2 days under a protective atmosphere of nitrogen at room temperature. Additional details are given elsewhere (7, 8, 14). All sample sheets thus prepared were gently extracted to remove the approximately 3 wt % soluble material they contained. 

EINECS 206-108-6 2-Ethylhexanoic acid tin(2-<-) salt Metacure T-9 NSC 75857 Nuocure 28 Stannous 2-ethylhexanoate Stannous 2-ethylhexoate Stannous octoate Tin 2-ethylhexanoate Tin bis(2-ethylhexanoate) Tin diocloate Tin ethylhexanoate Tin octoate Tin(2-r) 2-ethylhexanoate Tin(ll) 2-ethylhexanoate Tin(ll) 2-ethylhexylate Tin(ll) bis(2-ethylhexanoate). Catalyst used in production of PU coatings, adhesives, and sealants uniform activity and excellent stability. Arr Products Chemicals Inc. 

Stannous octoate (Sfannoos 2-ethylhexanoate), Sn[OOCCH(C2Hs)CH2CH2CH2-CH3]2. MoI. wt. 405.11. Suppliers Albright and Wilson Metal and Thermit Corp. (Catalyst T9) ROC/RTC. 

Lactide is produced by degradation reactions, mainly via intramolecular chain scission of the prepolymer. Lactide synthesis from a prepolymer with a DP in the range of 10-15 in the presence of various catalysts at 4-5 mbar and 190-245°C is reported by Noda and Okuyama [9]. The best performances were reported using 0.05-0.2 wt% tin catalysts and tin octoate (stannous 2-ethylhexanoate) in particular, which is widely available. The catalyst increases the rate of backbiting reactions from hydroxyl chain ends of prepolymers to form lactide molecules [9, 15]. The melt viscosity of the prepolymer increases because of the esterification reactions during the process, which results in decreased rate of mass transfer. 

Stannous 2-ethylhexanoate sta-nos e-thol-. hek-s9- no-at (stannous octanoate) n. A polymerization catalyst for urethane foam. 

Several polymerization methods, including melt, solution and emulsion have been applied to lactone monomers to form high molecular weight polymers. Typically, a catalyst such as a metal oxide or metal salt, stannous 2-ethylhexanoate or stannous chloride, is used along with a free hydroxy containing initiator such as water, an alcohol, hydroxy acid or ester to activate the lactone ring to initiate polymerization. 

Catalyst Systems A vast number of catalysts have been utilized in the ROP of lactide, of which the most studied are the carboxylates and alkoxides of Sn [111-120] and A1 [121-127]. Of these, stannous 2-ethylhexanoate (tin octanoate) is the most intensively studied. The polymerization mechanism is suggested to involve a preinitiation step, in which stannous 2-ethylhexanoate is converted to a stannous alkoxide by reaction with a hydroxyl-bearing compound. Then, the polymerization proceeds on the tin-oxygen bond of the alkoxide ligand, whereas the carboxylate itself is... 

Tin(II) 2-ethylhexanoate, commonly referred to as stannous octoate (Sn(Oct)2), is the most frequently used catalyst in the ROP and copolymerization of cyclic heterocyclic monomers including cyclic carbonates due to a high activity as well as an approval by the American Food and Drug Administration (FDA) as a food additive. The mechanism of polymerization with its contribution has been widely discussed. Sn(Oct)2 is not thought to be the actual initiator since the molecular weight does not depend on the monomer/Sn(Oct)2 molar ratio. 

Cyclic phosphates (12) were also polymerized using alcohol and/or macro initiators with hydroxy end groups as the initiators and tin(II) 2-ethylhexanoate (stannous octoate (Sn(Oct)2)) as catalyst, usually in THF at 30-40 °C or in bulk at 90 In long-term polymerization of structure 12 with... 

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