From BBC report.
For a deliberate handball, Football Association laws state:
there must be "movement of the hand towards the ball"
the "distance between opponent and the ball" should be considered
On this occasion, Sanchez did not look like he purposefully pushed the ball into the net and he had little time to move out of the way after the ball came off Jakupovic.
After consultation with his assistant, referee Mark Clattenburg awarded the goal, but prior to that in the first half, Theo Walcott had a shot blocked by the hand of Clucas inside the area, for which no penalty was given.
http://www.bbc.co.uk/sport/football/38865319