The calculated distance (air line) between Aleppo and Deir ez-Zor is approximately 177 miles respectively 286 kilometers.
By car or train, the actual journey to Deir ez-Zor is certainly longer, as only the direct route (as the crow flies) between Aleppo and Deir ez-Zor has been calculated here.
Air line (approximately)
286 kilometers
154 nautical miles