[methods] add CAS instructions for tangent function

diff --git a/chem/organic-2.md b/chem/organic-2.md
index 05cfd7482b539ba567f82d30cd7b16a1e9eb24d0..40a4de8369841b5ab33754962c2dce9a85116126 100644 (file)
--- a/chem/organic-2.md
+++ b/chem/organic-2.md
@@ -1,12 +1,15 @@
 ---
+geometry: a4paper, margin=2cm 
 header-includes:
 - \usepackage{mhchem}
+- \usepackage{chemfig}
 - \usepackage{tabularx}
 ---
 
 # Organic Chemistry
 
 Large number of compounds due to:
+
 - 4 valence pairs
 - single / double / triple bonds
 - cyclic (ring) structures
@@ -32,16 +35,36 @@ Alkynes: \ce{C_{$n$} H_{$2n-2$}}
 - Indicate number of branches with di-, tri- etc.
 - Longest unbranched carbon chain includes function group
 
-
-
 ## Functional groups
 
-\begin{tabularx}{\textwidth}{rX}
-  Alcohols & \ce{-OH} \\
-  Aldehydes & \ce{-CHO} \\
-  Ketones & \ce{-CO-} \\
-  Carboxylic acids & \ce{-COOH} \\
-  Amines & \ce{-NH2} \\
-  Amides & \ce{-CONH2} \\
+\setchemfig{atom sep=2em}
+\renewcommand{\arraystretch}{3}
+\begin{tabularx}{0.5\textwidth}{rlX}
+  \hline
+  Alcohols & \ce{-OH} & \chemfig{{\color{blue}R}-OH}\\\hline
+  Esters & \ce{-OCO-} & \chemfig{{\color{blue}R}-C(=[:-30]O)-[:30]O-{\color{blue}R}}\\\hline
+  Aldehydes & \ce{-CHO} & \chemfig{{\color{blue}R}-C(-[:-30]H)=[:30]O}\\\hline
+  Ketones & \ce{-CO-} & \chemfig{C(-[:150]{\color{blue}R})(-[:-150]{\color{blue}R})=O}\\\hline
+  Carboxylic acids & \ce{-COOH} & \chemfig{{\color{blue}R}-C(=[:-30]O)-[:30]O-H}\\\hline
+  Ethers & \ce{-O-} & \chemfig{{\color{blue}R}-[:210]O-[:-30]{\color{blue}R}}\\\hline
+  Amines & \ce{-NH2} & \chemfig{{\color{blue}R}-N(-[:-30]H)(-[:30]H)}\\\hline
+  Amides & \ce{-CONH2} & \chemfig{{\color{blue}R}-[:30]C(=[:90]O)-[:-30]N(-[:30]H)(-[:-30]H)}\\\hline
 \end{tabularx}
 
+
+## Isomers
+
+* **Structural isomers** - same molecular formula, different arrangement  
+* **Stereoisomers** - same structural configuration, different orientation  
+  * **Opotical isomers** - chiral centre, 4 groups bonded to C, non-superimposable mirror image
+  * **Geometric isomers** - \ce{C=C} double bond, 2 groups bonded to carbon atoms
+    + **Cis** - same horizontal plane
+    + **Trans** - diagonal
+
+\begin{center}\setlength\tabcolsep{1cm}
+\begin{tabularx}{0.5\textwidth}{cc}
+  cis & trans \\
+  \chemfig{[:60]{\text{\color{blue}R$^\prime$}}-C(-[:120]{\text{\color{red}R}})=[0]C(-[:-60]{\text{\color{blue}R$^\prime$}})-[:60]{\text{\color{red}R}}} &
+  \chemfig{[:60]{\text{\color{blue}R$^\prime$}}-C(-[:120]{\text{\color{red}R}})=[0]C(-[:-60]{\text{\color{red}R}})-[:60]{\text{\color{blue}R$^\prime$}}}
+\end{tabularx}\end{center}
+