NOVELTY - Preparing (P1) rivaroxaban (I) involves reacting (S)-4-(4-(5-(aminomethyl)-2-oxo-1,3-oxazolidin-3-yl)phenyl)morpholin-3-one (IV) or its salts with 5-chlorothiophene-2-carbonyl chloride in the presence of an organic base with a pKa of higher than 5.3, selected from N,N-diisopropylethylamine (DIPEA), trimethylamine, tripropyl amine, N-methylpiperidine, N,N-dimethylaminopyridine (DMAP), N-methylpyrrolidine, 1,4-diazabicyclo(2.2.2)octane (DABCO), 1,5-diazabicyclo(4.3.0)non-5-ene (DBN) and/or 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU).    USE - For preparation of Rivaroxaban (I) which is used as a medicament in the prophylaxis and/or treatment of thromboembolic diseases (claimed).    ADVANTAGE - The process is inexpensive, environmentally friendly, simple and economical process; produces rivaroxaban, which is free of impurities; and provides rivaroxaban in high yields.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a pharmaceutical composition comprising the rivaroxaban (I) obtained by the process (P1), and excipients;    (2) determining (P2) suitability for distribution of batch of rivaroxaban (I), or pharmaceutical composition containing the rivaroxaban (I) from the batch involving producing a batch of rivaroxaban, or pharmaceutical composition containing rivaroxaban from the batch; measuring the concentration of N,N'-bis(((5S)-2-oxo-3-(4-(3-oxomorpholin-4-yl)phenyl)-1,3-oxazolidin-5-yl)methyl)urea (Compound A) and/or the concentration of N,N'-bis((5S)-2-oxo-3-(4-(3-oxomorpholin-4-yl)phenyl)-1,3-oxazolidin-5-yl)methyl)benzene-1,2-diamide (Compound B) using respectively Compound (A) and/or Compound (B) as reference marker; and validating the batch for distribution only if the sample of the batch is free or substantially free of Compound (A) and/or Compound (B);    (3) an analytical process (P3) for determining the purity of a test sample containing rivaroxaban involving providing a reference sample containing rivaroxaban and at least one reference marker selected from N,N'-bis(((5S)-2-oxo-3-(4-(3-oxomorpholin-4-yl)phenyl)-1,3-oxazolidin-5-yl)methyl)urea (Compound A) and N,N'-bis((5S)-2-oxo-3-(4-(3-oxomorpholin-4-yl)phenyl)-1,3-oxazolidin-5-yl)methyl)benzene-1,2-diamide (Compound B); carrying out chromatographic separation on the reference sample to obtain a reference chromatographic result relative to the rivaroxaban of each one of the reference marker present in the reference sample; carrying out chromatographic separation on the test sample to obtain a test chromatographic result; and comparing the obtained chromatographic results, where if the test chromatographic result is substantially the same, as the reference chromatographic result for Compound (A), then the test sample comprises Compound (A) as an impurity, and if the test chromatographic result is substantially the same, as the reference chromatographic result for Compound (B), then the test sample comprises Compound (B) as an impurity;    (4) an analytical process (P4) for quantifying the purity of a test sample containing rivaroxaban involving a2) providing a test sample of rivaroxaban containing an unknown concentration of the compound (A) and/or the compound (B); b2) subjecting the test sample to chromatographic separation; c2) obtaining a chromatographic quantitative measurement for compound (A) and/or compound (B) in the test sample; and d2) calculating the amount of compound (A) and/or compound (B) in the test sample based on the measurement of step (c2) and also on a chromatographic quantitative measurement for compound (A) and/or compound (B) obtained from at least one reference sample having a known concentration of compound (A) and/or compound (B);    (5) new isolated N,N'-bis(((5S)-2-oxo-3-(4-(3-oxomorpholin-4-yl)phenyl)-1,3-oxazolidin-5-yl)methyl)urea (Compound A);    (6) preparing (P5) the Compound (A) involving reaction of (S)-4-(4-(5-(aminomethyl)-2-oxo-1,3-oxazolidin-3-yl)phenyl)morpholin-3-one (compound IV), or its salts, with any carbonyl activated compound selected from phosgene and its synthetic equivalents such as diphosgene or triphosgene, carbonyl diimidazole (CDI) and disuccinimidyl carbonate (DSC), where the compound (IV) is in excess with respect to the carbonyl activated compound;    (7) new isolated N,N'-bis((5S)-2-oxo-3-(4-(3-oxomorpholin-4-yl)phenyl)-1,3-oxazolidin-5-yl)methyl)benzene-1,2-diamide (Compound B); and    (8) preparing (P6) the compound (B) involving i) reacting (S)-2-((2-oxo-3-(4-(3-oxomorpholin-4-yl)phenyl)-1,3-oxazolidin-5-yl)methyl)-1H-isoindole-1,3(2H)-dione (compound III) with a sulfide salt, an hydrosulfide salt, and/or hydrogen sulfide, to obtain give (S)-2-(((2-oxo-3-(4-(3-oxomorpholin-4-yl)phenyl)-1,3-oxazolidin-5- yl)methyl)carbamoyl)benzoic acid (compound V); and ii) reacting the compound (V) with the compound (IV), or its salt, in the presence of a suitable activating agent.