FEAST process

The metathesis reaction of cycloalkenes yields linear unsaturated polymers, so-called polyalkenamers. This ROMP is driven by the release of ring strain in the starting material. Several interesting polymers are commercially produced via the ROMP of different types of unsaturated cyclic monomers such as cyclooctene, norbornene, and dicyclopentadiene, using homogeneous catalyst systems [6]. As an alternative process, the cross-metathesis between a cyclic and an acyclic olefin allows to synthesize certain poly-unsaturated compounds for the special chemical market. Shell [7] developed the FEAST process for the manufacture of hexa-l,5-diene via cross-metathesis of cycloocta-1,5-diene with ethene. 

One of the butadiene dimeri2ation products, COD, is commercially manufactured and used as an intermediate in a process called FEAST to produce linear a,C0-dienes (153). COD or cyclooctene [931-87-3], obtained from partial hydrogenation, is metathesi2ed with ethylene to produce 1,5-hexadiene [592-42-7] or 1,9-decadiene [1647-16-1], respectively. Many variations to make other diolefins have been demonstrated. Huls AG also metathesi2ed cyclooctene with itself to produce an elastomer useful in mbber blending (154). The cycHc cis,trans,trans-tn.en.e described above can be hydrogenated and oxidi2ed to manufacture dodecanedioic acid [693-23-2]. The product was used in the past for the production of the specialty nylon-6,12, Qiana (155,156). 

FEAST [Further exploitation of advanced Shell technology] Not a single process but a range of processes for converting cyclic di-olefins into alpha-omega dienes. The catalyst is based on rhenium on alumina. Operated in France since 1986. 

F. Cacialli, R.H. Friend, W.J. Feast, and P.W. Lovenich, Poly(distyrylbenzene- WocA>sexi(ethylene oxide)), a highly luminescent processible derivative of PPV, Chem. Common., 1778-1779, 2001. 

In agreement with Flory s predictions, hyperbranched polymers based on A,jB monomers reported in the literature exhibit a broad molecular weight distribution (typically 2-5 or more). The polydispersity of a hyperbranched polymer is due to the statistical growth process. A strategy to overcome this disadvantage is to add a By-functional core molecule, or a chain terminator, which Hmits the polydispersity and also provides a tool to control the molecular weight of the final polymer. The concept of copolymerizing an A2B monomer with a B3 functional core molecule was first introduced by Hult et al. [62] and more recently also utilized by Feast and Stainton [63] and Moore and Bharathi [64]. 

W.J. Feast, E. Khosravi, and T. Leejarkpai, Process for polymerization of cycloolefins and polymerizable cycloolefins, US Patent 6677418, assigned to University of Durham (Durham, GB), January 13,2004. 

Unsubstituted polyacetylene, like many other conductive polymers, is an intractable material and thus its processing into useful shapes and morphologies is limited. One solution to the processing problems has been the use of soluble precursor polymers that can be transformed into conductive polymers. Application of ROMP in the formation of soluble polyacetylene precursors was elegantly pioneered by Feast and coworkers [61]. Using this approach, a precursor polymer is synthesized by the ROMP of a cyclobutene derivative. Once synthesized, the precursor polymer can undergo a thermally promoted, retro-Diels Alder reaction to split off an aromatic fragment and produce polyacetylene, Eq. (42). 

Feast. Dibenzoylbenzene derivative (114) was irradiated with tetramethylallene for 3.5 minutes in benzene to produce a polymeric structure in which there were 90% oxetane structures incorporated along the backbone. This process constitutes an example of step-growth photopolymerization via the triplet state of an aromatic carbonyl moiety. The products are thermally unstable and readily degraded by acids, but are quite soluble in organic solvents and may possess useful properties as new materials. 

Andrews and Feast d have described a further application of the Patemo-Buchi reaction in which furans are used in step-growth polymerization. Irradiation of m-dibenzoylbenzene and furan produced the monomeric 2 1 adduct (182), which was polymerized further with m-dibenzoylbenzene to produce polymers containing isomeric oxetane units. The step-growth polymerization in this case was limited by low monomer solubility, slow oxetane formation, and hydrogen abstraction processes that led to crosslinking. 

Terminal dienes (also called a,w-diolefins) are useful in ADMET polymerization. The scheme below shows a number of processes that were patented by Shell Oil Company and were designed to produce terminal dienes. The name FEAST (Further Exploitation of Advanced Shell Technology) was coined to describe these reactions, most of which involve metathesis. Assume that the catalyst is a generic carbene complex, L M=CRR. Propose mechanisms for the transformations indicated by an asterisk near the reaction arrow. 

Chaumont, P. and John, C. S. (1988) Olefin Disproportionation Technology (Feast) -A Challenge For Process Development, J. Mol Catal, 46, 317-328. 

The Validation protocol should clearly describe the procedure to be followed for performing validation. The protocol should include at feast the objectives of validation and qualification study, site of the study, the responsible personnel, description of equipment to be used (including calibration before and after validation). SOPs to be followed, standards and criteria for the relevant products and processes, the type of validation, and time/frequency should be stipulated. The processes and/br parameters to be validated (e.g., mixing times, drying temperatures, particle size, drying times, physical characteristics, content uniformity etc.) should be clearly identified. 

Many of these problems have been solved by Feast (1985), who developed a very elegant synthetic method, now commonly known as the Durham route. This is a two-stage process in which soluble precursor polymers are prepared by a metathesis ringopening polymerization reaction, and these are subsequently heated to produce polyacetylene by a thermal elimination reaction. An example of the method is given below ... 

This work discusses the use of different processes for PHA production by activated sludge enhanced biological phosphorus removal (EBPR), microaerophilic-aerobic process and aerobic periodic feeding (feast/famine conditions). 

Apply to over 90% of PHA containing cells Employ a feast and famine selection process to find a robust PHA production strain The use of robust PHA production strains, better imder a nonsterUization condition The manipulation of the N-terminus of PHA synthase The development of low-cost technology for production of low-cost PHA biofuels or fuel additives Plant molecular biology... 

Feast, W.J., J. Tsibouklis, K.L. Pouwer, L. Groenendaal, and E.W. Meijer. 1996. Synthesis, processing and material properties of conjugated polymers. Polymer 37 5017. 

Feast, W.J. and Khosravi, E. (1995) Recent Development in ROMP , Chapter 3 in New Methods of Polymer Synthesis , Vol 2, edits Ebdon J.R. and Eastmond G.C., Blackie Academic and Professional Grubbs, R.H. and Khosravi, E. (1998) ROMP and related processes , in Synthesis of Polymers- A Volume of Materials Science and Technology, ed. Schluter, A.-D., Wiley-VCH, Chapter 3, 65-104. Feast, W.J., Gibson, V.C. and Marshall, E.L. (1992) J. Chem. Soc., Chem. Conunun. 1157. 

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