Cyclic carbonate applications

The structure of the amine catalyst and its concentration proved to be critical to selective formation of cyclic carbonates. Application of EtaN at 0.1 M concentration led to nearly exclusive formation of cyclic oligomers (90%). Examination of other... 

The cyclic carbonate of benzoin (4,5-diphenyl-l,3-dioxol-2-one, prepared from benzoin and phosgene) blocks both hydrogen atoms of primary amines after dehydration acid stable, easily crystallizable Sheehan oxazolinones are formed, which are also called Ox derivatives. The amine is quantitatively deblocked by catalytic hydrogenation in the presence of 1 equiv. of aqueous acid (J.C Sheehan, 1972, 1973 M.J. Miller, 1983). An intelligent application to syntheses of acid labile -lactams is given in the previous section (p. 161). 

Choquette et al. investigated the possibilities of using a series of substituted sulfamides as possible electrolyte solvents (Table 12). These compounds are polar but viscous liquids at ambient temperature, with viscosities and dielectric constants ranging between 3 and 5 mPa s and 30 and 60, respectively, depending on the alkyl substituents on amide nitrogens. The ion conductivities that could be achieved from the neat solutions of Lilm in these sulfamides are similar to that for BEG, that is, in the vicinity of 10 S cm Like BEG, it should be suitable as a polar cosolvent used in a mixed solvent system, though the less-than-satisfactory anodic stability of the sulfamide family might become a drawback that prevents their application as electrolyte solvents, because usually the polar components in an electrolyte system are responsible for the stabilization of the cathode material surface. As measured on a GC electrode, the oxidative decomposition of these compounds occurs around 4.3—4.6 V when 100 fik cm was used as the cutoff criterion, far below that for cyclic carbonate-based solvents. 

Shibasiki Y, Sanada H, Yokoi M, Sanda F, Endo T (2000) Activated monomer cationic polymerization of lactones and the application to well-defined block copolymer synthesis with seven-membered cyclic carbonate. Macromolecules 33 4316-4320... 

The scope of the substrates is further explored. A series of epoxides are chosen to be tested for the synthesis of the corresponding carbonates under the reaction conditions (BrTBDPEG150TBDBr 1 mol %, 120 °C, 0.1 and 1 MPa, 3-20 h). The catalyst can be applicable to a variety of terminal epoxides, providing the corresponding cyclic carbonates in high yields (> 93 %) and excellent selectivities (> 99 %). 

PEG proves to be an efficient reaction medium for the reaction of vicinal halohydrin with carbon dioxide in the presence of a base to synthesize cyclic carbonates (Scheme 5.9) [42], Notably, PEG400 (MW = 400) as an environmentally friendly solvent exhibits a unique influence on reactivity compared with conventional organic solvents. Various cyclic carbonates can be prepared in high yield employing this protocol. The process presented here has potential applications in the industrial production of cyclic carbonates because of its simplicity, cost benefits, ready availability of starting materials, and mild reaction conditions. 

The formation of cyclic carbonates of polysaccharides for biopolymer insolubilization [20] has been described and has found application in the preparation of immunosorbents. Coupling of enzymes to polysaccharides, glass and nylon structures using titanium halides has been described [21]. In this case coupling is through hydroxyl groupings. 

Besides the many acid sensitive derivatives, base labile protecting groups for 1,2-diols were also recommended. With phosgene or a chlorofoimate, cyclic carbonates are formed from cis- and trans-diols. They are stable to the conditions that hydrolyze acetals but are readily removed by saponification. (Tyclic boronates may also be used, but their application is limited because they hydrolyze very rapidly... 

Enantiomerically pure functional polycarbonate was synthesized from a novel seven-membered cyclic carbonate monomer derived from naturally occurring L-tartaric acid [99]. The ROP catalyzed by Novozym 435 was performed in bulk, at 80 °C, for 48h to afford optically active polycarbonate with M = 15500 g/mol and PDI 1.7 (Scheme 4.17). Hydroxy group functionality in the carbonate chain was achieved by deprotection of the ketal group. The polycarbonates have potential in biomedical applications. 

Nonetheless, for the more than 50 years since the first publication in this field, NIPUs still do not have sufficiently broad application. This can be explained by certain features of these materials. Cyclic carbonate (CC) groups interact with aliphatic and cycloaliphatic polyamines at ambient temperatures more slowly than isocyanates with hydroxyl groups. The rate of this reaction is comparable to the rate of curing epoxy resins (ER) with amines. At the same time, the CCs react only with primary amino groups, in contrast to the ERs, which react with primary and with secondary amino groups. This results in a decrease in cross-linking density of the polymer network. 

Five-membered cyclic carbonates are easily available as a result of the insertion of gaseous carbon dioxide into an oxirane ring (see review [12.]). Recent work in the field of new methods for preparing cyclic carbonates is dedicated primarily to the development of new catalytic systems and the synthesis of monofunctional compounds from epoxides and carbon dioxide (see, for example, reviews [13-16]). Monocyclic carbonates are used in a wide spectrum of applications solvents, components of liquid electrolytes, reactive diluents, chemical intermediates, and so on. It should be noted that this preparation also solves the problem of chemical fixation and utilization of C02. 

Leykin, A., Beilin, D., Birukova, O., Figovsky, O., and Shapovalov L. Nonisocyanate Polyurethanes Based on Cyclic Carbonate Chemistry and Application (review), Scientific Israel Technological Advantages 11, nos. 3—4 (2009) 160-190. 

Webster, D. C., and Crain, A. L. Synthesis and Applications of Cyclic Carbonate Functional Polymers in Thermosetting Coatings, Progress in Organic Coatings (2000) 275-282. 

Aluminum porphyrins are versatile initiators which are applicable to controlled ring-opening polymerization of various heterocyclic monomers (Table 1) such as epoxides (11)," oxetanes (12) lactones with four-, six-, and seven-membered rings (13-15), lactide (16), six-membered cyclic carbonates (17) and cyclic siloxanes (19).-" They are also excellent initiators for the controlled addition polymerization of unsaturated monomers such as acrylates (20), methacrylates (21)-- and methacrylonitrile (22).- - ... 

Titanium complexes have been shown to be active for the synthesis of cyclic carbonates or either di- or trithiocarbonates from epoxides and either carbon dioxide or carbon disulfide (Scheme 5.6). Titanium-catalysed synthesis of cyclic carbonates has been recently reviewed by North and coworkers. Titanium-salen complexes find application as catalysts, in combination with tetrabutylammonium bromide or tributylamine, for the synthesis of di- or trithiocarbonates from epoxides and carbon disulfide. It is worth highlighting that the catalyst loading can be reduced to 0.5 mol%, although 1 mol% of catalyst was required in order to achieve quantitative yields. The catalyst system showed a preference for dithiocarbonate formation for most of the epoxides studied. 

The carbonate and thiocaibonate derivatives used in the carbohydrate field have been reviewed 112]. The cyclic carbonates are sensitive to alkali and stable to add hydrolysis, and in these respects are complementary to the cydic isopropylidene acetals. Cydic carborrates may be made from sugars by the action of chloroformate esters. The original phosgerre method is also applicable, either directly or in a solvent. The solvent usually used is toluene, or a reaction-promoting solvent such as pyridine or quinoline may be used. 

Most importantly, layered materials are currently of particular interest as supports for the immobihzation and/or intercalation of various ILs in order to prepare polymer nanocomposites [83, 84] with improved thermal and mechanical properties, nanohybrid materials for electrochemical sensors [85, 86], and efficient catalysts for the synthesis of cyclic carbonate by the cycloaddition of CO2 to allyl glycidyl ether [87] and propylene glycol methyl ether (PGME) from propylene oxide and methanol [88]. A detailed list of applications involving layered materials and ILs can be found in a recent review [16]. 

---