1# Organic Chemistry 2 3Organic compounds > 90% of known chemicals 4Carbon makes living systems possible 5 6Carbon forms 4 covalent bonds (4 valence pairs) 7Strong bonds with other non-metals 8Bonds with itself with single, double or triple 9Can form chains or rings 10 11Large number of compounds due to: 12-4 valence pairs 13- single / double / triple bonds 14- cyclic (ring) structures 15 16 17## Hydrocarbons 18 19Hydrocarbons - only carbon and hydrogen 20If all C-C bonds are single, the hydrocarbon is saturated 21 22Hydrocarbons 23- linear (aliphatic) 24- - saturated (all single C-C bonds) 25- - - alkane ($C_n H_{2n+2}$) 26- - unsaturated 27- - - alkene ($C_n H_{2n}$) 28- - - alkyne ($C_n H_{2n-2}$) 29- 30- cyclic (ring) 31- - saturated 32- - - e.g. cyclohexane 33- - unsaturated 34- - - e.g. benzene 35 36Carbon compounds with 4 branches are tetrahedral 37 38Compounds with $C-H$ are insoluble in water 39These compounds are almost non-polar due to similar electronegativities 40 41Only dispersion forces (between electrons on the outside of two molecules) hold each molecule together 42Dispersion forces increase with size (chain length), therefore MP and BP of straight molecules increases with length 43 44Branched molecules have lower MP and BP due to lower density (molecules are further apart due to their shape, so dispersion forces are weaker) 45 46Homologous series - formula for molecules (e.g. alkanes, alkenes, alkynes) where each member differs by some increment 47 48Structural isomers - same molecular formula, different configuration (structural formula) 49 50## Alkanes 51$$C_n H_{2n+2}$$ 52- Single bonds between carbon atoms 53- ending in *-ane* 54 55methane $CH_4$ 56ethane $C_2H_6$ 57propane $C_3H_8$ 58butane $C_4H_10$ 59pentane $C_5H_12$ 60hexane $C_6H_14$ 61$\dots$ 62 63Alkanes burn in oxygen forming $CO_2 + H_2O$ (oxidation / combustion reaction) 64 65Alkanes react with chlorine or fluorine (substitution reaction) - Cl or F replace H. Result is a haloalkane. 66 67## Alkenes 68 69$$C_nH_{2n}$$ 70 71- C-C double bond 72- ending in *-ene* 73 74methene $CH_2$ 75ethene $C_2H_4$ 76propene $C_3H_6$ 77butene $C_4H_8$ 78pentene $C_5H_10$ 79hexene $C_6H_12$ 80$\dots$ 81 82Alkenes burn in oxygen forming $H_2O + CO_2$. 83 84Alkenes react with hydrogen or a halogen (addition reaction) - additive breaks the double bond (catalyst is required). 85 86## Alkynes 87 88$$C_nH_{2n-2}$$ 89 90- C-C triple bond 91- ending in *-yne* 92 93Alkynes undergo combustion (oxidation) and addition reactions (same as alkenes). 94 95## Rules for naming HCs 96 971. Find longest chain of C atoms (incl. branches) 982. Start at end nearest a branch or double/triple bond 993. Name carbon atoms from end chosen 1004. Branches end with *-yl* 1015. When there are $\ge$ 2 branches, number of C atom is indicated before each branch, and names are in alphabetic order. 1026. When there are $\ge$ 2 identical branches, *di-*, *tri-*, and *tetra-* are used. 103 104## Combustion 105 106$$C_xH_y+z0_2 \to\ xCO_2+{y \over 2}H_2O$$ 107$$z=x+{y \over 4}$$ 108 109## Functional groups 110 111Atom(s), or a bond, which give a properties to an organic molecule. 112 113### Alcohols / hydroxyls 114 115- ---OH functional group 116- ends in *-ol* 117- alcohols have multiple isomers 118- combustible with oxygen 119- BP and MP are affected by H-bonding 120- **H-bonds are represented by dotted lines** 121 122### Carboxylic acids / carboxys 123 124- ---COOH functional group 125- ends in *-oic acid* 126- first portion of name (e.g. **methan**oic acid) refers to **total** number of carbons 127- weak acids (proton from O is donated) 128- high BP 129 130#### Esters 131- reacts with alcohols to form esters (condensation / esterification) 132- catalyst is $H_2SO_4$ 133- low boiling points 134- intermolecular bonding is dipole-dipole and dispersion rather than H-bonding 135- ends in *-oate* rather than *-oic*