My company closed 141 transactions last year. I want to know how many transactions is it per minute?

That is a very precise measure, not really applicable to the business. "Last year" is not good enough, you have to say exactly how many minutes in the period. For one thing, your company probably did not close any deals before 9:00 AM or after 5:00 PM, so that means 960 minutes every day that are not part of the calculations.

And besides that, why would anybody be interested in "transactions per minute"?