• ${\mathrm{S}}_{\mathrm{N}}1$ reaction
  
• ${\mathrm{S}}_{\mathrm{N}}2$ reaction
  
• Neither ${\mathrm{S}}_{\mathrm{N}}1$ nor ${\mathrm{S}}_{\mathrm{N}}2$ reaction
  
• ${\mathrm{S}}_{\mathrm{N}}2$ reaction as well as ${\mathrm{S}}_{\mathrm{N}}1$ reaction