Answer by David Carlisle for Tabularx: Column smaller than text

TeX can not hyphenate the first word of a paragraph, put

\hspace*{0pt}

at the start of the X cells, for example you can add this to every X cell by using

>{\hspace*{0pt}}X 

in your tabular preamble

but it may need help hyphenating the chemical terms with \- depending on which natural language patterns you are using, You may need

\usepackage[german]{babel} %German?

As those words will not hyphenate well with the default English patterns.

You may also consider using a smaller font so it fits better