Cdc recommends mix infant formula with water at temperature at least 158f. i am wondering whether there is a maximum temperature? will temperature like 185f break down any nutrition or create bad chemicals?

I never would: I don't know where you got your info but don't believe the CDC would suggest this and would NEVER do it. Baby formula should be placed in bottles cleaned as you would common dishes/utensils preferably using hot water but it is not necessary to sterilize them. It can then be mixed at room temperature using hygienic methods. I agree that high temps would break down the nutrients.