TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The process alternatively comprises after the step of directing the first and second light phases to MR-2; directing the third light phase, the second dense phase from MR-1B and a recycled dense phase to a catalyst extraction system (SEXT-1) to give the fourth dense and light phase; directing the fourth light phase to SP-1; directing one part of the fourth dense phase to form the recycled dense phase for SEXT-1, a second part to form the fifth dense phase containing residual catalyst, and the remainder to SREC-1; and directing any excess from the dense phases to SREC-1. The process additionally comprises the alternative reaction steps of passing the second dense phase through an alcohol evaporation/distillation system (SEVAP-2) and then directing a liquid phase to SEXT-1; and directing alcohol removed to SREC-1. The process comprises the alternative purification steps of: either directing the third light phase to SN-1 and then separating the resulting products into the fourth dense and light phase; directing the fourth light phase to SEXT-2, and the fourth dense phase to SREC-1; promoting in SEXT-2, with the aid of recovered glycerine, extraction of part of the excess alcohol retained in the fourth light phase, to prevent hydration of this alcohol by contact with water from (SLAV-1) to obtaining and separating the fifth dense phase, which is sent to SREC-1 to recover anhydrous or semi-anhydrous alcohol, and the fifth light phase; directing the fifth light phase to SLAV-1, which also receives water, in order to remove water-soluble contaminants in the fifth light phase, and separating the resulting product into the aqueous phase, which is directed to SREC-1, and a sixth light phase; directing the sixth light phase to a drying and SSRC-1, from which (I) is recovered; or directing the third light phase to SEXT-2, which also receives recovered glycerine from SREC-1, to promote extraction of part of the excess alcohol retained in the third light phase, to prevent hydration of the alcohol by contact with water from SLAV-1 to obtaining the fourth dense and light phase; separating and directing the fourth dense phase to SREC-1 to recover anhydrous or semi-anhydrous alcohol; directing the fourth light phase to SN-1 to react with the neutralizing agent, and then separating the resulting products into the fifth dense phase, which is directed to SREC-1, and the fifth light phase; directing the fifth light phase to SLAV-1, which also receives water, in order to remove water-soluble contaminants in the fifth light phase, and separating the resulting product into the sixth dense aqueous phase, which is directed to SREC-1, and the sixth light phase; and directing the sixth light phase to a drying and SSRC-1, from which (I) is recovered. The process comprises before washing in SLAV-1, the neutralized light phase is submitted to an additional step of evaporation or distillation of excess alcohol, where the step includes directing the light phase to SEVAP-1 to remove part or all of the residual alcohol content, separating and directing the alcohol removed and a dense phase to SREC-1, while the light phase is sent to SLAV-1. The dense phase arriving at SREC-1 enters this system at specific point in accordance with the contents of water and the decision to be adopted as to type of recovery. The type of recovery involves premixing of the fractions or, alternatively separate treatment of the aqueous fractions, recovering all of the glycerine from the aqueous fractions or only treating them for disposal, converting the soaps in fatty acids and recovering the fatty acids or otherwise, and/or dehydrating the recovered alcohol or offering it for sale as hydrated alcohol (when the process uses ethyl alcohol). The natural oil and/or fat includes castor oil, pine nut oil, soybean oil, cottonseed oil, rapeseed oil, sunflower oil, ouricury palm oil and or any natural fat, pure or mixed, virgin and/or reused. The alcohol is a pure 1-6C alcohol or its mixture, preferably pure methanol and/or ethanol. The molar ratio of alcohol/(oil or fat) is 4-15. The catalyst is an acid or basic catalyst, where if a basic catalyst is used for the transesterification reaction, the neutralizing agent can be any organic or inorganic acid, strong or weak, concentrated or dilute, in aqueous or alcoholic solution, as long as the turning point of the neutralization of the catalyst is carefully controlled, and the water for washing is pure or with pH controlled in the range of 1-7, preferably 3-5. The acids are preferably hydrochloric, sulfuric, phosphoric, acetic and citric acids. The acidic buffers in the desired pH range can optionally be used in order to facilitate control. The process includes three reaction steps, two reaction steps in parallel (R-1A and R-1B) using oil or fat as a starting material, and one reaction step in series (R-2) using as a starting material the light phases produced in the earlier reaction steps (R-1A and R-1B). The two initial steps (R-1B) reuses the catalyst used in the other steps. The reuse of the catalyst is accomplished by means of a fraction, which comprises totally or partially of first and third dense phases separated in (MR-1A and MR-2), where the fraction comprises first, third and fifth dense phases. The third light phase forwarded for purification is produced by any type of reaction process using an acid or basic catalyst. The proportion of basic catalyst to oil or fat is 0.1-2.5 wt.% of oil/fat starting material in the unit.