P-Butyrolactone

Data were last reviewed in lARC (1976) and the compound was classified in lARC Monographs Supplement 7 (1987). 

Abstr Services Reg. No.. 3068-88-0 Systematic name. 4-Methyl-2-oxetanone 

2 Structural and molecular formulae and relative molecular mass 

P-Butyrolactone has been used in the preparation of p-o ybutyiy l-/ r/ra-phcnctidinc 

P-Butyrolactone was tested for carcinogenicity in mice by skin application and by subcutaneous injection and in rats by oral administration and by subcutaneous injection. It produced tumours at the site of administration in both species (lARC, 1976). 

---

N-Heterocyclic carbenes are an example of a family of nucleophilic catalysts [84-87]. For instance, the polymerization of p-butyrolactone was catalyzed by l,3,4-triphenyl-4,5-dihydro-l//,l,2-triazol-5-ylidene in the presence of methanol as an initiator [86]. This reaction was carried out in toluene at 80 °C. Nevertheless, an undesired elimination (Fig. 4) reaction was observed and control of the polymerization was lost. This issue was overcome by using ferf-butanol as a co-solvent, which reacts reversibly with the free carbene to form a new adduct. Owing to the decrease in the concentration of the free carbene, the elimination is disfavored and the polymerization is then under control provided that a degree of polymerization below 200 is targeted. As a rule, the reactivity of N-heterocyclic carbenes depends on their substituents. Hindered N-heterocyclic carbenes turned out to be not nucleophilic enough for the ROP of sCL. Recently, it was shown that unencumbered N-heterocyclic carbenes were more efficient catalysts [87]. 

When l,8-diaza[5.4.0]bicycloundec-7-ene (DBU) and N-methylated TBD (MTBD) were used as catalysts instead of TBD, no polymerization was observed, even with catalyst loading of up to 20 mol% [89]. The lack of activity of these amines was accounted for by the absence of any activation of the lactone, and the activation of the alcohol turned out to be not sufficient. However, the polymerization was successfully carried out by the addition of a thiourea as a co-catalyst to activate lactones, as shown in Fig. 23. Again, p-butyrolactone was not reactive enough and was not polymerized [89]. 

Ajellal N, Thomas CM, Carpentier J-F (2009) Functional syndiotacticpoly(P-hydroxyalkanoate)s via stereoselective ring-opening copolymerization of rac-P-butyrolactone and rac-allyl-P-butyrolactone. J Polym Sci A Polym Chem 47 3177-3189... 

Hemminki, K. (1981) Reactions of P-propiolactone, p-butyrolactone and y-butyrolactone with nucleic acids. Chem.-biol. Interact., 34, 323-331... 

No epidemiological data relevant to the carcinogenicity of P-butyrolactone were available. 

There is sufficient evidence in experimental animals for the carcinogenicity of P-butyrolactone. 

Similarly, if p-butyrolactone is treated with the cyclic alkoxide 2,2-dibutyl-l,3,2-di-oxastannolane, the cyclic trimer and higher oligomers are formed.59... 

In addition to bis-bisoxazolinate complexes 177 and 178, chiral and nonchi-ral bis-bisoxazolinate rare-earth metal complexes were synthesized to investigate their catalytic activity for ROP of D,L-lactide and D,L-P-butyrolactone [134]. By using the same synthetic pathway as for compounds 177 and 178, bis-bisoxazolinate complexes 179-182 were obtained via the amine elimination reactions of 2 equiv of the corresponding bisoxazolines HL33-HL35 with 1 equiv of [Ln N(SiHMe2)2 3(THF)2] (Ln = Y, La) in benzene or toluene (Scheme 68). 

All complexes 177-182 showed high catalytic activity in the ROP of D,L-lactide (Scheme 14) and D,L-p-butyrolactone (Scheme 69) [134]. The polymerization reactions proceeded at room temperature with turnover frequencies of up to 31,200 h and turnover numbers of up to 2,400. The reactions occurred in a controlled fashion, giving polymers with relatively narrow polydispersities = 1.08-1.44). 

Discrete cationic aluminum complexes of Co(CO)4 have unprecedented activity and selectivity for epoxide carbonylation (Scheme 6.109) [14]. Complex 9 carbony-lated propylene oxide with 95% conversion in 1 h under a high pressure of CO. Because (-i-P)- -butyrolactone is of particular interest for polymerization and other asymmetric transformations, (P) -propylene oxide was treated wifh CO and catalyst 9. Propylene oxide was converted to (P)- -butyrolactone wifh >98% retention of configuration. 

---