# Why \chemand produces [0pt]+ in mychemistry?

I was writing chemical reaction using mychemistry package. I have a problem with \chemand which produces [0pt]+ as output in pdflatex. How can I get rid of the [0pt]?

\begin{rxn}
\reactant{\chemname{\chemfig{*6(------)}}{Cyclohexane}}
\arrow[,,1.50]{\scriptsize Pt on}{\scriptsize \ch{Al2O3xH2O}}
\reactant{\chemname{\chemfig{**6(------)}}{Benzene}}
\chemand
\reactant{3\ch{H2}}
\end{rxn}


• The mychemistry package is classified as obsolete by its author. The wrong output is due to an internally called \chemsign macro that's not defined any longer. – egreg Nov 13 '17 at 9:02
• As commented above the package is obsolete and should not be used. If you do want to use it, then for this specific issue you can add \newcommand{\chemsign}[2][]{#2} below \usepackage{mychemistry} which will output a (somewhat misaligned) + sign for the MWE. – Marijn Nov 13 '17 at 10:17
• Thank you very much. I usually use mhchem package to write simple chemical reactions and did not know that mychemistry package is obsolete ! I think I better use chemfig as Mr. Clemens suggested. – Jeffrey Nov 14 '17 at 11:58

The mychemistry package is obsolete and not updated any longer (the last update was nearly 5 years ago). It used to have its purposes before v1.0 of chemfig was published on 2011/06/15. Since v1.0 chemfig comes with a built-in mechanism for reaction schemes.

mychemistry used to build upon chemfig which means it also uses commands provided by chemfig. chemfig used to have a command called \chemsign until v1.2 (2015/10/08). chemfig itself removed this command in favor of its more advanced scheme mechanism.

The scheme from the OP without mychemistry:

\documentclass{article}

\usepackage{chemfig}
\usepackage{chemformula}

\begin{document}

\begin{center}
\schemestart
\chemname{\chemfig{*6(------)}}{Cyclohexane}
\arrow{->[\scriptsize Pt on][\scriptsize \ch{Al2O3xH2O}]}[,2]
\chemname{\chemfig{**6(------)}}{Benzene}
\+
\ch{3 H2}
\schemestop
\end{center}

\end{document}


• Oh thank you Sir !! I didn't know that the package became obsolete. Thanks for your explanation and correction. It works now ! – Jeffrey Nov 14 '17 at 11:55