mjhjmtu

I'm trying to use this as my starting guide for using sed to add a line to a file in OSX.
https://stackoverflow.com/questions/25631989/sed-insert-line-command-osx

sed -i '.json' '2i
this is a test place
 ' dummy.txt

The above works. But I need to do expansion so I'm starting with something simple by just replacing with double quotes like

sed -i '.json' "2i
this is a test place
 " dummy.txt

Why do I get command i expects followed by text? Or how do I use double quotes on Mac to add text to a specific line?