**7. Reaction with dimethyl carbonate (DMC)**

The third route is to obtain FAME from a reaction between triglycerides and dimethyl carbonate. Unlike all the other pathways described, this reaction takes place in two reversible steps: in the first, a DMC molecule reacts with a triglyceride molecule, releasing two FAME molecules and an intermediate, the fatty acid glycerol carbonate (FAGC - fatty). acid glycerol carbonate). In the second step, the FAGC molecule reacts with the second DMC molecule to form a FAME molecule and the by-product of the route, glycerol dicarbonate [25]. The reaction and its stoichiometry are shown in **Figure 7**.

DMC is an attractive reagent because it can be considered a green alternative in the organic synthesis industry and has several applications as a methylation and carbonylation agent. It is a non-toxic and biodegradable substance, which is obtained by environmentally interesting routes. The most used industrial route today is the oxidative carbonylation of methanol with carbon monoxide and oxygen, catalyzed by copper(I) chloride. As methanol and carbon monoxide can be obtained from biomass synthesis gas, obtaining biodiesel using DMC from this route would only use reagents of renewable origin [26–28].

Another important point is the fact that DMC does not decompose at temperatures lower than 390°C, so using it as a reagent in supercritical processes is viable [29].

**Figure 7.** *Two-step reaction with dimethyl carbonate. Source: adapted from [25].*

#### **Figure 8.**

Biodiesel production by this route via supercritical process was studied using crude oils of *Jatropha curcas* and *pongamia pinnata* as raw material and DMC and diethyl carbonate as reagents, in a batch reactor, optimizing parameters such as molar ratio, temperature and reaction time. For all experiments, carried out at 15 MPa, the highest conversion obtained was for the system with *pongamia* oil and DMC, which shows that dimethyl carbonate is more reactive than diethyl carbonate [30].

The two-stage route, as well as for the methanol and acetic acid routes, has the advantage of being able to apply milder process conditions to avoid product degradation. However, this pathway generates glycerol as a by-product, although this can be converted to glycerol carbonate, a compound with greater added value, when reacting with DMC [29, 31].

The mixture of FAME and glycerol dicarbonate can be used as biodiesel, without harming its properties, as well as with triacetin. After the reaction to obtain FAME and the removal of excess dimethyl carbonate, the remaining product – FAME and DCG – was analyzed, showing that its properties were within the parameters established by the American and European standards. However, as it is an intermediate for glycerol carbonate, a compound with a high market value, glycerol dicarbonate and FAME can also be separated in a distillation column, depending on the strategy and economic feasibility of the process [30]. The complete flowsheet for the described process is shown in **Figure 8**.

### **8. Conclusions**

This chapter shows the potential of soy as a raw material for a biorefinery, that is, obtaining several high added value products through different technological routes. The residues of this oilseed can be used to obtain these products with high added value without competing with the food sector. Routes that make the production of

*Routes to Aggregate Value to Soybean Products DOI: http://dx.doi.org/10.5772/intechopen.102615*

biodiesel viable are real and technically feasible, in addition to the generation of co-products of greater interest such as: tocopherols, sterols, squalene, triacetin, DCG. Another interesting point is the flexibility that some products allow when generated together with the esters, as they do not interfere with the quality of the biofuel. Soy has a wide range of exploration possibilities, and its production follows the pace of industrial production. Studies that make its development economically viable are the biggest challenge, as the technical feasibility is well consolidated.
