Rhen or Rhein: How To spell?

The word Rhen is misspelled against Rhein, a noun meaning "Chrysophanic acid."

Word contains consecutive vowels 'EI' in between alphabets rh & n is misspelled as 'E' as letter 'I' is phonetically ignored
Wrong Spelling:  rh-e-n 
Correct Spelling:  rh-ei-n 
Explore spell check of Rhein to spell without errors.