From nothing to ignition of a fire, especially if the HC has double bonds
actually this type of reaction were used to distinguish between alkyne ,alkene than alkane and aromatic system. simply ;as u know π-electrons of alkenes and alkynes are very reactive toward sulfuric acid (and other sources of H+). The π-electrons attack the H+ to form a carbocation, which either reacts with the bisulfate anion or react with the π−system of another alkene . Alkynes also react similarly while Alkanes and aromatics do not produce any visible reaction with concentrated sulfuric acid under these conditions.
Thanks a lot for your answers
I want to know can sulfuric acid oxidize crude oil and decrease its organic content?
Crude oil is a complex mixture of hydrocarbons together with minor components of nitrogen-, oxygen-, and sulfur- containing organic compounds. The hydrocarbons are largely alkanes mainly , cycloalkanes in the second place, few aromatics, and few alkenes.Alkynes are not found in crude oil.
Alkanes & cycloalkanes do not react with conc. sulfuric acid.
Alkenes react with H2SO4 and form carbocations. If no nucleophilic reagent is present besides the acid, alkyl sulfates are obtained.
The aromatics (benzene & its derivatives) get protonated by H2SO4 causing the formation of unstable species & if there is a nucleophile present then the reaction will proceed into what is called (electrophilic aromatic substitution).
S-compounds could be H2S (inorganic) ,mercaptans or thiols (R-S-H), heterocyclic (e.g. thiophene), and disulfides (R-S-S-R'). H2S acts as a base in front of H2SO4 and an acid-base reaction is expected. R-S-H & thiophene ,for instance, get protonated by sulfuric acid and reactions proceed if there are nucleophiles.
O- compounds include alcohols (R-O-H) & these are similar to (R-S-H) in their behavior. Ethers also get protonated & carboxylic acids will act in basic manner with H2SO4.
As for the organic nitrogen compounds, most of them are heterocyclic & generally speaking they are bases so acid-base reactions are expected.
Apart from the paraffins(i.e. alkanes) & naphthenes (i.e. cycloalkanes), the other ingredients of crude oil are minor and ,therefore, their reactions are not very significant practically. These reactions are studied for the sake of knowledge.