Are IRA RMD distributions allowed to go to a charity instead of to the IRS?

IRA distributions go to you, not the IRS, but if you are asking about the tax on IRA distributions then yes, you can have the trustee of the IRA make a direct transfer to a recognized charity (a QCD - Qualified Charitable Contribution) and that will not add to your taxable income.

See IRS Pub 590B

https://www.irs.gov/publications/p590b#en_US_2017_publink100041439

"Qualified charitable distributions.

A qualified charitable distribution (QCD) is generally a nontaxable distribution made directly by the trustee of your IRA (other than a SEP or SIMPLE IRA) to an organization eligible to receive tax deductible contributions. You must be at least age 70½ when the distribution was made. Also, you must have the same type of acknowledgment of your contribution that you would need to claim a deduction for a charitable contribution. See Records To Keep in Pub. 526.

The maximum annual exclusion for QCDs is $100,000. Any QCD in excess of the $100,000 exclusion limit is included in income as any other distribution. If you file a joint return, your spouse can also have a QCD and exclude up to $100,000. The amount of the QCD is limited to the amount of the distribution that would otherwise be included in income. If your IRA includes nondeductible contributions, the distribution is first considered to be paid out of otherwise taxable income.

A QCD will count towards your required minimum distribution.

You can't claim a charitable contribution deduction for any QCD not included in your income."