Synthesis of Glycerol Carbonate

The glycerolysis of urea represents an alternative synthetic approach for the synthesis of glycerol carbonate (Equation 7.26) ... 

The major problem of the direct carbonatation of alcohols is of course the formation of water and the unfavorable thermodynamics of the process. Attempts to overcome this problem include the addition of water-trapping agents or start from alcohol derivatives such as ortho esters. A number of such experiments have been carried out under conditions considerably beyond the critical data of pure CO2 [88]. The presence of the supercritical phase as a solvent was explicitly addressed in the synthesis of glycerol carbonate from glycerol and CO2 [89]. The tin-catalyzed conversion of trimethyl ortho ester to dimethyl carbonate in SCCO2 occurred with up to ca. 30 catalytic turnovers, whereby the highest yields and selectivities were observed in the vicinity of the critical pressure of pure CO2 [90]. 

Vieville C, Yoo JW, Palet S, Mouloungui Z (1998) Synthesis of glycerol carbonate by direct carbonatation of glycerol in supercritical CO2 in the presence of zeolites and ion exchange resins. Catal Lett 56 245-247... 

Aresta M, Dibenedetto A, Nocito F, Ferragina C (2009) Valorization of bio-glycerol new catalytic materials for the synthesis of glycerol carbonate via glycerolysis of urea J Catal 268 106-114... 

Scheme 4 Synthesis of glycerol carbonate from epihalohydrins and potassium bicarbonate.

Scheme 6.36 Synthesis routes and utilizations of glycerol carbonate.

A benzyl carbonate was prepared in 83% yield from the sodium alkoxide of glycerol and benzyl chloroformate (20°, 24 h). It is cleaved by hydrogenolysis (H2/ Pd-C, EtOH, 20°, 2 h, 2 atm, 76% yield) and electrolytic reduction (-2.7 V, R4N X, DMF, 70% yield). A benzyl carbonate was used to protect the hy-droxyl group in lactic acid during a peptide synthesis. 

Triglycerides are nontoxic, biodegradable and renewable molecules which are being used as substrate for the synthesis of a variety of useful molecules such as glycerol esters, fatty acid alkyl esters, triacetin, ketals, acetals, glycerol carbonates, etc (Scheme 1). 

The interconversion of fructose-6-phosphate and fructose-1,6 bis phosphate is a control point in glycolysis and gluconeogenesis. Gluconeogenesis is a pathway which allows carbon atoms from substrates such as lactate, glycerol and some amino acids to be used for the synthesis of glucose, so it is in effect physiologically the opposite of... 

Two isomers of chirally deuterated glycerol have been synthesized from a common boronic ester intermediate 1 (synthesis Section I.I.2.1.3.I.)71. (15,25)-Glycerol-l-fi results if the carbon to which the label is attached is derived from dibromomethane and incorporated into an a-bromo boronic ester intermediate 2, which is then reduced with potassium triisopropoxyborodeuteride to the (1 / ,2/ )-l-deutero boronic ester 3. The synthesis of (lS,25)-glycerol-l- / is completed efficiently by dcboronation with hydrogen peroxide and debenzylation with hydrogen over palladium. 

Other compound classes in the synthesis of which chiral 3-carbon synthons were used include sphingosine chains (32), 3-amino-2-azetidinones (33), (3,y-unsaturated-a-amino acids 34), fluorinated macrocyclic bis(indolyl) maleimides35, fluorocyclopropyl alcohols (36), l-O-phosphocholine-2-O-acyl-octadecanes and l-Ophosphocholine-2-N-acyl-octadecane (37) diacyl glycerols 38-42) and analogs of fragments of leukotriene-B4 43). 

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