Replace backtick with single quote using sed or awk

I want to replace all backticks (`´`) with single quotation marks (`'`) in specific text document using sed or awk inside of PHP shell_exec() without using hexadecimal or octal code. At first, I tried these commands running inside of shell script: ``` sed -e 's/´/'"'"'/g' file.txt; sed -e 's/\´/'"'"'/g' file.txt; sed -e 's/´/'/g' file.txt; sed -e 's/\´/'/g' file.txt; sed -e 's/"´"/'"'"'/g' file.txt; awk '{gsub(/\´/, "\'" ) }1' file.txt; ``` but none of these worked. Example of input.txt file: ``` abc´def´123`foo'456; ``` Example of output.txt file: ``` abc'def'123`foo'456 ``` Using sed command running from terminal this solution works: ``` echo "a´b´c;" | sed "s/´/'/g" ``` and output is: ``` a'b'c; ``` but running it from executable file test.sh: ``` #!bin/bash sed "s/´/'/g" input.txt > output.txt ``` as shell script executed by command ``` bash test.sh ``` it doesn't work and content of output.txt file is same as content of input.txt file. However, with forward tick it works and result of ``` #!bin/bash sed "s/\`/'/g" input.txt > output.txt ``` is output.txt file with content ``` abc´def´123'foo'456; ``` However, when I try to replace backward ticks with single quotation marks using hex or octal representation of characters it works like a charm. Using sed: ``` input.txt - abc´def´123`foo'456; command - sed 's/\xB4/'"'"'/g' input.txt > output.txt; output.txt - abc'def'123`foo'456 ``` Using awk: ``` input.txt - abc´def´123`foo'456; command - awk '{gsub(/\264/, "\047" )}1' input.txt > output.txt; output.txt - abc'def'123`foo'456 ``` Problem is, that I'm using another script applied to the document with mentioned script that replaces every hexadecimal or octal code with its literal representation. I'm able to do it another way, I'm just curious if mentioned replacement can be used without using hex or octal code.