# Synthesis of Biodiesel by Interestricification of Triglycerides with Methyl Formate
## 1 Introduction  
In industry, biodiesel is produced by the process of transesterification of oil (triglycerides) with short-chain alcohols, with the commonly used alcohol being methanol [1, 2]. Catalysts, mostly alkaline, are used to accelerate the reaction [3, 4]. The transesterification process produces fatty acid methyl esters (biodiesel) and a by-product, the glycerol phase or crude glycerol, which is formed in about 10% [5, 6]. The composition of the glycerol phase varies, depending on the biodiesel production technology, but consists of 80-90 wt.% of glycerol and impurities: alcohol, catalyst, esters, and unreacted oil [7]. Crude glycerol can be used for technical purposes: for freeze protection for coal, as a dust suppressant, in grain storage, as an energy source, for the cultivation of microalgae, and the formation of munching coatings [8, 9]. Pure glycerol is more in demand. It can be used in pharmaceuticals, food, feed, fuel and other industry [10, 11]; however, the process of purifying the glycerol phase to pure glycerol requires considerable energy and material costs. With increasing biodiesel production, excess glycerol is emerging in the market [12, 13]. The absence of glycerol in the production of biodiesel would lead to a higher yield of biodiesel, could solve the problems of glycerol purification and utilization, and, at the same time, make the biodiesel production process more economical. It is known that triacylglycerol glycerol or triacetin can be produced from glycerol [14, 15]. This product is highly soluble in biodiesel and improves its low-temperature properties [16]. However, the separate production of triacetin and blending with biodiesel to improve the low-temperature properties is uneconomical. The researchers began to study the process of synthesis, which directly produces a mixture of biodiesel and triacetin. No glycerol phase is formed during the process [17, 18]. The resulting product is not inferior in quality to biodiesel, and it has better low-temperature properties than biodiesel. The fuel obtained during the intereesterification process has an advantage over biofuels, since there is no need to use synthetic depressants, improving the low-temperature properties of biofuels. The prices of industrially obtained depressants are high, and even small quantities increase the cost of biofuels. Such product is obtained by intereesterification of triglycerides with short chain carboxylate esters. The process produces two types of esters: fatty acid esters (conventional biodiesel) and esters of glycerol and carboxylic acids of low molecular mass (Figure 1). In the production of biofuels, food grade oil is most often used for the intereesterification of triglycerides with short chain carboxylate esters. Most studies were conducted using rapeseed oil [19; 20]; additionally, the process of intereesterification was studied using soybean oil [21; 22], olive oil [23; 24], and sunflower oil [25; 26]. Some studies have also been carried out using oil, which is not used for food because of the harmful compounds contained in it. Scientists have studied the possibilities of using Pongamia pinnata (karanja) [26], cotton oil [27], Jatropha oil [26], palm oil [28], and insect fat [29]. The processes of interetification of the generated oil waste (waste cooking oil [30], waste canola oil [30], and the characteristics of the products obtained were also analyzed. Most research has been performed, and the best results have been obtained for intereesterification using methyl and ethyl acetates [20; 28; 31; 32; 33; 34; 35]. The physical chemical properties of the manufactured fuel and compliance with the requirements of the standard were studied by scientists. [PERSON] et al. found that the fuel produced by intereesterification of marine microslag Chlorella sativa oil with methyl acetate met the requirements of the standard (ASTM D675). When compared with jatropha methyl esters, it was found that there were no differences between the different types of biofuels [36].