How do I account for transactions that were business expenses, but paid with a personal acct that is not connected to our QB Online? I don't want to connect it the acct.

Enter the expenses using the Owner's Equity account, as increases to the account.

I personally like to set up a cash clearing account for all things of this type.  (like a cash on hand) type. The balance of this account should always land being zero but having it makes it easier to find whether or not you entered something from a personal cc charge, or personal cash, or personal checking. whichever.. it reduces the potential that anything will get entered twice by accident and gives you one solid place to look to ensure you forgot nothing.

In the Cash Clearing register I would enter and record all those expenses to the correct expenses accounts.

Then, to zero the account out, I will simply post a deposit to that register and offset that deposit against Owner Draw - Draw Cash (if a proprietor) .  This would debit all expenses and credit the draw . . If you are an LLC it's Member's Draw - Draw Cash or you could use Owner Contribution or Member Contribution to offset.  All of the draws get closed out to Owner's equity after the close of the year, 1/1/new year.  I would do this Deposit entry weekly, monthly, etc depending on how often you use personal cash to pay business items. 

Also, when using QB Online, I recommend always attaching receipts so if an audit ever occurs, you have the backup required to support the expenses.

@EKeough 

Do you need to reimburse the expense from your business account to personal account?