S-caprolactone

The chemical properties of cycHc ketones also vary with ring size. Lower members (addition reactions, than corresponding acycHc ketones. The Cg—C 2 ketones are unreactive, reflecting the strain and high enol content of medium-sized ring systems. Lactones are prepared from cycHc ketones by the Bayer-ViUiger oxidation reaction with peracids. S-Caprolactone is manufactured from cyclohexane by this process ... 

Copolymers of S-caprolactone and L-lactide are elastomeric when prepared from 25% S-caprolactone and 75% L-lactide, and rigid when prepared from 10% S-caprolactone and 90% L-lactide (47). Blends of poly-DL-lactide and polycaprolactone polymers are another way to achieve unique elastomeric properties. Copolymers of S-caprolactone and glycoHde have been evaluated in fiber form as potential absorbable sutures. Strong, flexible monofilaments have been produced which maintain 11—37% of initial tensile strength after two weeks in vivo (48). 

Poly(s-Caprolactone) Copolymers with Glycolide or Lactide.228... 

A star copolymer (SCP) of PCLA was synthesized by Younes and coworkers. This kind of SCP PCLA elastomer was also synthesized in two steps. First, the small molecular SCP was produced by ring-opening polymerization of s-caprolactone (s-CL) with glycerol as initiator and stannous 2-ethyUiexanoate as catalyst. Second, the living SCP was further reacted with different ratios of a cross-linking monomer, such as 2,2-bis(s-CL-4-yl)-propane (BCP) and s-CL. The SCP elastomers had very low glass transition temperature (—32°C). It was reported that the SCPs were soft and weak with physical properties similar to those of natural bioelastomers such as elastin. A logarithmic decrease in each tensile property with time was observed in this SCP PCLA. 

Although the biocompatibility and biodegradability of these materials were rapidly determined, the bioactivity of Si02-PCL hybrid materials was not studied until recently [99]. In order to provide bioactivity to Si02-PCL hybrid materials, Rhee prepared triethoxysilane end-capped poly(s-caprolactone) which was then cocondensed with tetraethyl orthosilicate and calcium nitrate via the sol-gel method. The Ca-containing PCL/silica hybrid so obtained showed in vitro bioactivity and biodegradability. The hybridization procedure between the a,co-hydroxyl PCL and silica phases was proposed to be as follows ... 

Yasuda et al. [122] extended the above work to the block copolymerization of ethylene with lactones. 5-Valerolactone and s-caprolactone were combined with the growing polyethylene end at ambient temperature and the expected AB-type copolymers (100 1 to 100 89) were obtained at high yield. Reversed addition of the monomers (first MMA or lactones and then ethylene) induced no block copolymerization at all, even in the presence of excess ethylene, and only homo-poly(MMA) and homo-poly(lactone) were produced. 

The study of benzaldehyde and cyclohaxanone co-oxidation showed the formation of s-caprolactone as the main product of cyclohexanone oxidation [5]. Cyclohexanone was found not to react practically with peroxyl radicals under mild conditions. The oxidation of benzaldehyde produces perbenzoic acid. The latter oxidizes the benzaldehyde to benzoic acid and cyclohexanone to s-caprolactone. 

Interestingly, enzymes are chiral catalysts and their potential for enantio-selective polymerization has been investigated [93]. Several examples are reported where a racemic mixture of lactones is polymerized by enzymatic polymerization to afford the corresponding optically active polyester [93]. For instance, lipase CA (Novozym 435) catalyses the ROP of racemic 4-methyl-s-caprolactone and 4-ethyl-s-caprolactone in bulk at 45 °C and 60 °C to afford (S )-eiuiched poly(4-methyl-e-caprolactone) and poly(4-ethyl- -caprolactone) with an enantiomeric purity higher than 95% [153]. 

Finally, Lecomte and coworkers reported the synthesis of mikto-arm star-shaped aliphatic polyesters by implementing a strategy based on click chemistry (Fig. 36) [162]. Firstly, the polymerization of sCL was initiated by a diol bearing an alkyne function. The chain-ends were protected from any further undesired reaction by the esterification reaction with acetyl chloride. The alkyne was then reacted with 3-azidopropan-l-ol. The hydroxyl function located at the middle of the chain was then used to initiate the ROP of sCL and y-bromo-s-caprolactone. Finally, pendant bromides were reacted successfully with sodium azide and then with N, N-dimethylprop-2-yn-l-amine to obtain pendant amines. Under acidic conditions, pendant amines were protonated and the polymer turned out to exhibit amphiphilic properties. 

Frechet and coworkers reported a first example of the synthesis of a hyperbranched aliphatic polyester by polymerization of an AB inimer, i.e., 4-(hydroxyethyl)-s-caprolactone [164]. It is worth noting that the synthesis of this inimer is quite long. Since this pioneering work, other teams have reported the polymerization of a series of AB [165-167] and AB2 [168] inimers, which are shown in Fig. 38. The polymerization of these inimers can be carried out in the absence or presence of a comonomer such as sCL [167]. 

Stassin F, Jerome R (2003) Effect of pressure and temperature upon tin aUcoxide-promoted ring-opening polymerisation of s-caprolactone in supercritical carbon dioxide. Chem Commun 232-233... 

Lang M, Wong RP, Chu C-C (2002) Synthesis and structural analysis of functionalized poly (s-caprolactone)-based three arm star polymers. J Polym Sci A Polym Chem 40 1127-1141... 

The general issues from literature surveys dealing with lanthanide initiators reveal the following (1) catalyst precursors with larger lanthanide metals polymerize lactide faster than metals of smaller radii, (2) lanthanide catalysts polymerize lactide at slower rates than cyclic esters such as s-caprolactone and, in most cases. 

Aldonolactones serve as suitable monomers for the generation of homo- and copolymers, especially through ring-opening polymerization (ROP). Among them are the carbohydrate-analogs of s-caprolactone, i.e., aldono-1,6-lactones. The first example of such derivatives and further ROP was reported by Galbis and co-workers [61], see also chapter, Synthetic polymers from readily available monosaccharides ... 

Scheme 8 Enzymatic polymerization of various substituted s-caprolactones...

A reaction vessel was charged with the step 2 product, poly (s-caprolactone), poly-(caprolactone) diol (100 g), and antimony trioxide (0.2 g) heated to 100°C for 30 minutes and the temperature gradually increased to 160°C under a very high vacuum for... 

Kennedy and Stock reported the first use of Oxone for many common oxidation reactions such as formation of benzoic acid from toluene and of benzaldehyde, of ben-zophenone from diphenylmethane, of fratw-cyclohexanediol from cyclohexene, of acetone from 2-propanol, of hydroquinone from phenol, of s-caprolactone from cyclohexanone, of pyrocatechol from salicylaldehyde, of p-dinitrosobenzene from p-phenylenediamine, of phenylacetic acid from 2-phenethylamine, of dodecylsulfonic acid from dodecyl mercaptan, of diphenyl sulfone from diphenyl sulfide, of triphenylphosphine oxide from triphenylphosphine, of iodoxy benzene from iodobenzene, of benzyl chloride from toluene using NaCl and Oxone and bromination of 2-octene using KBr and Oxone126. Thus, they... 

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