IN ORDER TO, SO AS TO,

• In  order to  / so as to
• In  order  not to / so as not to
• In order that / so  that
• he  hid the present  in  order  that the  children  wouldn't find itç
•  +  to infinitive  (purpose  of an  action)
• I'm going to  university to  become a teacher
• I'm saving to buy a car

• For + ing ( purpose  of  a thing)
• The mobile phone is for  calling  other  people
• Thisthing  is for  getting rid of  headaches

•  SO startling  was the scene  that I'll never forgive it
• It  was SO startling  that  I  started to  cry

http://www.bbc.co.uk/learningenglish/english/course/towards-advanced/unit-6/session-1