What to do to align text with chemfig molecules

chemfigchemistry

I'd like the letters to be in the middle of structures. I know that the letters are in the place where the code of each structures begins, but I have no idea how to change it, without changing the code :/. Can someone help me, please?

\documentclass{article}
\usepackage{chemfig}
\begin{document}
a. \chemfig{-[,.8]-[::72,.8](-[:18,.6]CH_2CH_3)-[::72,.8](-[2,.6,1]CH_3)-[::72,.8]-[::72,.8]} \vspace{0.5cm} \\
c. \chemfig{-[,.6]-[::51.43,.6](-[:-12.86,.6]CH_3)-[::51.43,.6](-[::-64.28,.6]CH_2CH_3)-[::51.43,.6]-[::51.43,.6](-[::-64.28,.6]Br)-[::51.43,.6]-[::51.43,.6]} \vspace{0.5cm} \\
b. \chemfig{-[6,.6]-[::60,.6]-[::60,.6](-[:-30,.6]CH_3)-[::60,.6]-[::60,.6](-[2,.6]CH_3)-[::60,.6]} \vspace{0.9cm}\\
d. \chemfig{-[6,.6]-[::60,.6]-[::60,.6](-[::-60,.6]Cl)-[::60,.6](-[::-60,.6]CH(-[:90,.6,1]CH_3)-[::-60,.6,1]CH_3)-[::60,.6]-[::60,.6]}
\end{document}

Best Answer

A suggestion

\documentclass{article}
\usepackage{amsmath}
\usepackage{chemfig}
\begin{document}
\begin{align*}
    & \schemestart
     a. \arrow{0} \chemfig{-[,.8]-[::72,.8](-[:18,.6]CH_2CH_3)-[::72,.8](-[2,.6,1]CH_3)-[::72,.8]-[::72,.8]}
    \schemestop \\ 
    & \\
     %
&   \schemestart
    c. \arrow{0} \chemfig{-[,.6]-[::51.43,.6](-[:-12.86,.6]CH_3)-[::51.43,.6](-[::-64.28,.6]CH_2CH_3)-[::51.43,.6]-[::51.43,.6](-[::-64.28,.6]Br)-[::51.43,.6]-[::51.43,.6]}
    \schemestop \\
        & \\
     %
&    \schemestart
    b. \arrow{0} \chemfig{-[6,.6]-[::60,.6]-[::60,.6](-[:-30,.6]CH_3)-[::60,.6]-[::60,.6](-[2,.6]CH_3)-[::60,.6]} 
    %
    \schemestop \\
        & \\
    %
&   \schemestart
    d. \arrow{0} \chemfig{-[6,.6]-[::60,.6]-[::60,.6](-[::-60,.6]Cl)-[::60,.6](-[::-60,.6]CH(-[:90,.6,1]CH_3)-[::-60,.6,1]CH_3)-[::60,.6]-[::60,.6]}
\schemestop
\end{align*}
\end{document}

I used an invisible arrow (\arrow{0}) to create an empty space. You can vary this space by varying the length of the arrow.

Related Solutions

[Tex/LaTex] chemfig: reaction above arrow

As I understand the question, the problem is in the "label" of the arrow and how to do the "circle" with arrows. One way to do this is to play with the properties of chemmove and the arrows.

For example:

\schemestart
\chemfig{First molecule}
\arrow{->[
\chemname[24pt]{\chemfig{N@{st1}ADH}}{\scriptsize \parbox[c]{40pt}{\centering ammonium formate}}
\hspace{0.5cm}
\chemname[24pt]{\chemfig{N@{en1}AD}}{\chemfig{CO_2}}
\chemmove{\draw[->,shorten <=5pt, shorten >=5pt](st1) .. controls +(+50:8mm) and +(+130:8mm)..(en1);}
\chemmove{\draw[->,shorten <=5pt, shorten >=5pt](en1) .. controls +(-130:8mm) and +(-50:8mm)..(st1);}
\chemmove{\draw[->,shorten <=5pt, shorten >=5pt,transform canvas={yshift=-32pt}](st1) .. controls +(+50:8mm) and +(+130:8mm)..(en1);}
]}[,2.4]
\chemfig{second molecule}
\schemestop

Note that maybe further adjusting of the spaces is required.

[Tex/LaTex] How to align text, structures, and arrows in chemfig package

Not sure if this is the best way to go about doing it, but you can specify the anchor points used for the middle arrow, then manually shift the epxido molecule upwards with a yshift. I've marked out the changes in the following code:

\documentclass{article}
\usepackage{chemfig}

\begin{document}    

\begin{figure}
    \centering
    \scalebox{.6}{
    \chemnameinit{\chemfig{[:210]O*3(-(-R|^1)-(-R|^2)-)}}
    %\schemedebug{true} % Activate to see anchor points
    \schemestart
    \chemname{%
        \chemfig{R^1-=-R^2}
        }{Alqueno}
    \+
    \chemname{%
        \chemfig{H_2O_2}
        }{Peróxido\\de hidrógeno}
    \arrow(.mid east--.mid west) % <--------
        {->[Base][Disolvente]}[0,2] 
    \chemname{%
        \chemfig[yshift=2em]{[:210]O*3(-(-R|^1)-(-R|^2)-)} % <--------
        }{Epóxido}
    \+
    \chemname{%
        \chemfig{H_2O}
        }{Agua}
    \schemestop
    \chemnameinit{}
    }
    \caption{Reacción de epoxidación. Oxidación de un alqueno en presencia de un peróxido de hidrógeno y una base orgánica.}
    \label{fig:2}
\end{figure}

\end{document}

Addendum

You can have a look at the anchor points and how chemfig groups the molecules together using \schemedebug{true} placed before \schemestart (Uncomment it in the above code to see what I mean). It's useful when trying to align the arrows, +, and molecules in a reaction scheme.

Best Answer

Related Solutions

[Tex/LaTex] chemfig: reaction above arrow

[Tex/LaTex] How to align text, structures, and arrows in chemfig package

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