14.1 Alkanes

Alkanes can be formed via
1. h__ of a__ (e__ a__)
2. c__ longer chain alkane w/ __ catalyst + heat
> bc smaller = u__

hydrogenation, alkene, electrophilic addition, cracking, Al2O3, useful

Forming alkanes:
Hydrogenation of a__
> conditions: __/Ni catalyst + h__
> a__ + H₂ → alkane

alkene, Pt, heat, alkene

Reactions of alkanes
1. C__
2. f__-r__ s__ (to make h__)

combustion, free-radical substitution, halogenoalkanes

Alkanes are generally u__ bc s__ d__ in e-n__ between C & _ THUS is n__-p__ (so no dipoles)

unreactive, small diff, negativities, H, non-polar

Reactions of alkanes: combustion
> complete: alkane + O₂ → __ + __
> incomplete: alkane + O₂ → __ + __
>> this gas is t__ & colourless & N oxides can lead to a__ rain & kill t__/fish
>> c__ converters help: CO + O₂ ;; N oxides r__ ;; unburnt HCs oxidised

CO2, H2O, CO, H2O, toxic, acid, trees, catalytic, reduced

Reactions of alkanes: free radical substitution to make halogenoalkanes
> needs __ (sun) ;; H atom substituted by Cl/Br
> not suitable for making s__ halogenoalkanes

UV, specific

Free-radical subst.:
1st step: __
> Cl-Cl bond broken by __ = 2 r__ (h__ fission)

initiation, UV, radicals, homolytic

Free-radical subst.:
2nd step: __
> Free r__ attack unreactive a__ = 1 C-H bond breaks = a__ radical + HX
>> CH₃CH₃ + Cl• → •CH₂CH₃ + HCl
> Alkyl radical attacks h__ = h__ + halogen radical
>> •CH₂CH₃ + Cl-Cl → CH₃CH₂Cl + Cl•
> repeat

propagation, radicals, alkane, alkyl, halogen, halogenoalkane

Free-radical subst.:
3rd step: __
> 2 free r__ react → _ product
•CH₂CH₃ + •CH₂CH₃ → … OR •CH₂CH₃ + •Cl → … OR •Cl + •Cl → …

termination, radicals, 1