NOVELTY - Producing N-acyl amino acid based surfactants comprises: (a) preparing fatty acid chlorides by halogenating fatty acids with either phosgene or thionyl chloride in the presence of catalytic amount of same or other N-acyl amino acid surfactant (I) or anhydrides of same surfactant; and (b) reacting fatty acid chloride of step (a) with an amino acid in the presence of a base under typical aqueous Schotten-Baumann conditions such that the process does not employ a step of purification (Incomplete specification, abstract based on available information).    USE - The method is useful for producing N-acyl amino acid based surfactants (claimed), or corresponding anhydrides as catalysts.    ADVANTAGE - Cost-effective two-step process for manufacturing amino acid based surfactants using same surfactants as catalysts for synthesizing the intermediate of high quality and with quantitative yield is provided. The catalyst for the intermediate acid chloride is the same surfactant that is being manufactured and hence the intermediate fatty acid chloride does not have to be purified by additional steps (distillation/crystallization) that often lead to the substantial loss of yield and increased batch cycle time and increased energy consumption. Unlike the processes of the prior art, the process uses completely degradable catalyst for the manufacture of the intermediate acid chlorides. The N-acyl surfactant catalysts work equally well with both industrial halogenating agents. The catalysts work very well with phosgene and thionyl chloride while creating fatty acid chloride. The by-product of phosgenation is carbon dioxide (CO2) where with thionyl chloride, the by-product is sulfur dioxide (SO2) that can be converted into surfuryl chloride and subsequently thionyl chloride by a well established closed loop chemistry. Since the distillation/crystallization/phase separation steps are obviated during the manufacture of fatty acid chloride, there is no generation of effluent and hence in addition to the advantage of lesser energy consumption, a significant saving on the waste disposal is accomplished. Thus, the process of making N-acyl surfactants is completely green and nothing is let out in the environment. Unlike the processes of the prior art, the process does not use any toxic catalysts and hence the issue of product isolation from the toxic catalyst does not arise. The process uses biodegradable and non-toxic catalysts. It involves lesser chemical engineering unit operations and offers high throughput with quantitative conversions and yield, thus making the process cost-effective as well as eco-friendly and sustainable.    DETAILED DESCRIPTION - Producing N-acyl amino acid based surfactants of Formula (I) (not given or available in the specification) comprises: (a) preparing fatty acid chlorides by halogenating fatty acids with either phosgene or thionyl chloride in the presence of catalytic amount of same or other N-acyl amino acid surfactant of Formula (I) or anhydrides of same surfactant of Formula (II) (not given or available in the specification); and (b) reacting fatty acid chloride of step (A) with an amino acid in the presence of a base under typical aqueous Schotten-Baumann conditions so that the process does not employ a step of purification (Incomplete specification, abstract based on available information).    R=6-22C alkyl group;    R1=H, or 1-4C alkyl;    R2=selected from all carbon groups of natural amino acids;    R3=selected from COOX, and CH2-SO3X;    X=Li+, Na+ or K+, or C or SO (for formula II); and    n=0-4.