Observations of star forming regions at (sub)millimetre and centimetre wavelengths have allowed astronomers to detect numerous molecules including some of the most complex molecules ever observed in the interstellar medium. One of the best targets to study these complex organic molecules (COMs) is the Sagittarius B2 (Sgr B2) molecular cloud, located in the central molecular zone, close to the galactic center. Sgr B2 is one of the most prominent regions forming high-mass stars in our galaxy. The target of my project is one of its main centers of activity, Sgr B2(N). The EMoCA survey (Exploring molecular complexity with ALMA) has unveiled the presence of at least five dense and compact hot molecular cores in Sgr B2(N). In order to characterise these hot cores I analysed their spectra to derive physical properties and chemical composition. I use the chemical code MAGICKAL (Model for Astrophysical Gas and Ice Chemical Kinetics and Layering) to simulate the evolution of the chemical composition in the sources and compare the numerical predictions with the observations.