De or het syntheseroute?

The correct Dutch article is:

de syntheseroute

Rule Words ending in -te: usually de. See the rule

How to use syntheseroute

the syntheseroutede syntheseroute
this syntheseroutedeze syntheseroute
that syntheseroutedie syntheseroute
our syntheserouteonze syntheseroute
your syntheseroutejouw syntheseroute
every syntheserouteelke syntheseroute
which syntheseroute?welke syntheseroute?
a big syntheseroute / the big syntheserouteeen grote syntheseroute, de grote syntheseroute