NOVELTY - Forming 2-((2,2-dimethoxyethyl)amino)-N-(2-phenylethyl)acetamide (I) involves (a1) condensing beta -phenylethylamine with chloroacetylchloride in presence of solvent and base to form 2-chloro-N-phenethylacetamide (II); (b1) condensing benzylamine with chloroacetaldehydedimethylacetal in presence of water and base to form N-benzyl-2,2-dimethoxyethanamine (III); (c1) condensing compound (II) with (III) in presence of water and base to form 2-((2,2-dimethoxyethyl)benzylamino)-N-phenethylacetamide (IV); and (d1) reducing acetamide (IV) by reducing agent and solvent in presence of hydrogen.    USE - For forming 2-((2,2-dimethoxyethyl)amino)-N-(2-phenylethyl)acetamide which is useful as an intermediate in the preparation of praziquental (claimed) that is used for the treatment of a variety of worm infections, and against parasites such as cestodes.    ADVANTAGE - The method is a cost effective process for preparing Praziquantel in good yield and good purity on a commercial scale; and is green and environment-friendly. The present method avoids the use of expensive raw material aminoacetaldehyde dimethylacetal which is used in prior art in two equivalents, instead it makes a novel intermediate compound 2-((2,2- dimethoxyethyl)benzylamino)-N-phenethylacetamide in water, which is very inexpensive, and this reduces the overall cost of the praziquantel significantly.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) preparation of praziquental involving: cyclization of the acetamide (I), using an acid in presence of solvent to obtain 4-oxo-1,2,3,6,7,11b-hexahydro-4H-pyrazino(2,1-a)isoquinoline (VI); and acylation of the isoquinoline (VI) with cyclohexanoylchloride in presence of a base and solvent;    (2) new intermediate selected from 2-((2,2-dimethoxyethyl)benzyl amino)-N-phenethylacetamide (IV); and    (3) new crystalline 4-oxo-1,2,3,6,7,11b-hexahydro-4H-pyrazino(2,1-a)isoquinoline having powdered X-Ray diffractogram as given in figure 1 of the specification.