The calculated distance (air line) between Alzenau in Unterfranken and Dortmund is approximately 121 miles respectively 194 kilometers.
By car or train, the actual journey to Dortmund is certainly longer, as only the direct route (as the crow flies) between Alzenau in Unterfranken and Dortmund has been calculated here.
Air line (approximately)
194 kilometers
105 nautical miles