Chase has a limit of $500,000 per day. A banker should be able to help you determine any immediate tax liabilities that will arise as a direct result of the transaction. You may wish to consult with a tax professional about any indirect implications the transfer may have.
This transaction will be reported to the government but assuming that you are not involved in any illegitamate activities the likelihood of the US government taking any action on the notice is incredibly low. I have heard of 7 and 14 day holds being placed on out of character transfers but if you are buying property you should work with your bank to help facilitate. Bankers understand the business and can help you avoid any appearances of impropriety that the government flags.
Should your account be flagged, I would retain a lawyer immediately. If you feel you have a reason to be concerned, then I would contact a lawyer in the US and Thailand before initiating the transfer. As they say an ounce of prevention is worth a pound of cure.