Andrew's git - notes.git/blob - chem/organic-2.md

   1---
   2geometry: a4paper, margin=2cm 
   3header-includes:
   4- \usepackage{mhchem}
   5- \usepackage{chemfig}
   6- \usepackage{tabularx}
   7---
   8
   9# Organic Chemistry
  10
  11Large number of compounds due to:
  12
  13- 4 valence pairs
  14- single / double / triple bonds
  15- cyclic (ring) structures
  16
  17## Properties of hydrocarbons
  18
  19- *Saturated* - all C-C bonds are single
  20- Insoluble in water
  21- Almost non-polar (similar electronegativities)
  22- Only dispersion forces (valence e-)
  23- Dispersion forces increase with length
  24- Branched molecules have lower density
  25
  26## Linear (aliphatic)
  27
  28Alkanes: \ce{C_{$n$} H_{$2n+2$}}  
  29Alkenes: \ce{C_{$n$} H_{$2n$}}  
  30Alkynes: \ce{C_{$n$} H_{$2n-2$}}
  31
  32## Naming hydrocarbons
  33
  34- Branches end with _-yl_
  35- Indicate number of branches with di-, tri- etc.
  36- Longest unbranched carbon chain includes function group
  37
  38## Functional groups
  39
  40\setchemfig{atom sep=2em}
  41\renewcommand{\arraystretch}{3}
  42\begin{tabularx}{0.5\textwidth}{rlX}
  43  \hline
  44  Alcohols & \ce{-OH} & \chemfig{{\color{blue}R}-OH}\\\hline
  45  Esters & \ce{-OCO-} & \chemfig{{\color{blue}R}-C(=[:-30]O)-[:30]O-{\color{blue}R}}\\\hline
  46  Aldehydes & \ce{-CHO} & \chemfig{{\color{blue}R}-C(-[:-30]H)=[:30]O}\\\hline
  47  Ketones & \ce{-CO-} & \chemfig{C(-[:150]{\color{blue}R})(-[:-150]{\color{blue}R})=O}\\\hline
  48  Carboxylic acids & \ce{-COOH} & \chemfig{{\color{blue}R}-C(=[:-30]O)-[:30]O-H}\\\hline
  49  Ethers & \ce{-O-} & \chemfig{{\color{blue}R}-[:210]O-[:-30]{\color{blue}R}}\\\hline
  50  Amines & \ce{-NH2} & \chemfig{{\color{blue}R}-N(-[:-30]H)(-[:30]H)}\\\hline
  51  Amides & \ce{-CONH2} & \chemfig{{\color{blue}R}-[:30]C(=[:90]O)-[:-30]N(-[:30]H)(-[:-30]H)}\\\hline
  52\end{tabularx}
  53
  54
  55## Isomers
  56
  57* **Structural isomers** - same molecular formula, different arrangement  
  58* **Stereoisomers** - same structural configuration, different orientation  
  59  * **Opotical isomers** - chiral centre, 4 groups bonded to C, non-superimposable mirror image
  60  * **Geometric isomers** - \ce{C=C} double bond, 2 groups bonded to carbon atoms
  61    + **Cis** - same horizontal plane
  62    + **Trans** - diagonal
  63
  64\begin{center}\setlength\tabcolsep{1cm}
  65\begin{tabularx}{0.5\textwidth}{cc}
  66  cis & trans \\
  67  \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}}} &
  68  \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$^\prime$}}}
  69\end{tabularx}\end{center}
  70
  71## Reactions
  72
  73**Cracking** - split moluecules with heat/pressure/catalyst
  74
  75### Alkanes
  76
  77- Relatively inert
  78- Non-polar solvent
  79- Non-soluble in \ce{H2O}
  80- Combusts in \ce{O2} (forms \ce{CO2 + H2O})
  81- Reacts with halogens (**substitution** of \ce{H})
  82
  83### Alkenes
  84
  85- More reactive than alkanes
  86- **Addition reactions**: \ce{C=C} bond is broken (energy released)
  87- **Addition polymerisation**
  88
  89### Alcohols
  90
  91- Can be formed from haloalkane substitution reaction
  92- **Oxidation** (combustion)
  93- Oxidation state $\propto$ no. of atoms connected to \ce{C}
  94- **Substitution** of functional group, e.g. \ce{ROH + NH3 -> RNH2 + H2O}
  95- Primary alcohols oxidise to aldehydes then carboxylic acids
  96- Secondary alcohols oxidise to ketones
  97
  98### Carboxylic acids
  99
 100- Weak acids
 101- **Hydrolysis**: \ce{RCOOH + H2O <=> RCOO^{-} + H2O^{+}}
 102- Rxn with amines - carboxylic acid + amine $\rightarrow$ ammonium salt $\rightarrow$ amide + water
 103
 104### Esterification
 105
 106- **Condensation reactions** (esterification): \ce{RCOOH + R^{$\prime$}OH -> RCOOR^{$\prime$} + H2O}
 107- This is reversed by **hydrolysis**: ester + water $\rightarrow$ carboxylic acid + alcohol
 108- Polyesters