Outline all steps in the synthesis of propyne from each of the following compounds, using any needed organic or inorganic reagents. (a) 1,2 -dibromopropane (e) n-propyl alcohol (b) propylene (f) 1,1 -dichloropropane (c) isopropy1 bromide (g) acetylene (d) propane (h) \(1,1,2,2\) -tetrabromopropane

(a) 1,2-dibromopropane: Perform an elimination reaction using excess alcoholic KOH to form propyne. \(CH_3CHBrCH_2Br + 2\ KOH \rightarrow CH_3C\equiv CH + 2KBr + 2H_2O\) (e) n-propyl alcohol: Oxidize with PCC to form propanal, then perform a Corey-Fuchs reaction using CBr_4, PPh_3, and t-BuLi to form propyne. (b) propylene: Perform a hydroboration-oxidation reaction using 9-BBN, H_2O_2, and NaOH to form propanal, then perform a Corey-Fuchs reaction using CBr_4, PPh_3, and t-BuLi to form propyne. (f) 1,1-dichloropropane: Perform a Grignard reaction with Mg, HCHO, and H_3O^+ to form n-propyl alcohol, then follow steps (e) to complete the synthesis. (c) isopropyl bromide: Perform a Grignard reaction with Mg, CO_2, and H_3O^+ to form propionic acid, perform a Hofmann rearrangement with Br_2, NaOH, and H_3O^+ to form n-propyl alcohol, then follow steps (e) to complete the synthesis. (g) acetylene: Perform an alkylation reaction with propyl bromide and NaNH_2 to form propyne. \(HC\equiv CH + CH_3CH_2CH_2Br + NaNH_2 \rightarrow CH_3C\equiv CH\) (d) propane: Synthesis of propyne from propane is not possible using simple organic chemistry transformations. (h) 1,1,2,2-tetrabromopropane: Perform two elimination reactions using excess alcoholic KOH to form propyne. \(CHBr_2CHBr_2 + 4\ KOH \rightarrow CH_3C\equiv CH + 4KBr + 4H_2O\)