You are not able to exclude your IRA distribution from federal tax if given as a gift to your son; regardless of the amount.
Only qualified
charitable distribution (QCD) is excluded from your federal taxable income: you must be over the age of 70 and 1/2 and the gift must be given to an organization that qualifies as charitable organization; gifts to individuals do not qualify, unfortunately.
One good note: Gifts are not reported as income by the recipient, so your son doesn't have to pay income tax on it.
