Michael Thorley has written:

'Vibrational spectra of alkylbenzenes and related model compounds for polymers'

Petroleum-derived diesel is composed of about 75% saturated hydrocarbons (primarily paraffins including n, iso, and cycloparaffins), and 25% aromatic hydrocarbons (including naphthalenes and alkylbenzenes).[24] The average chemical formula for common diesel fuel is C12H23, ranging approximately from C10H20 to C15H28

Diesel is produced from the fractional distillation of crude oil between 200 °C (392 °F) and 350 °C (662 °F) at 1 atm pressure, which is a mixture of carbon chains that contain between 8 and 21 carbon atoms per molecule.

There is no definite formula for diesel but the components remain the same. Means, they are composed of Carbon and Hydrogen with variable molecular ratio.

However, the average chemical formula for common diesel fuel is C12H23, ranging approximately from C10H20 to C15H28.

Please note: Diesel is composed of about saturated hydrocarbons (75% - approximately and primarily paraffins including n (normal), iso and cyclo-paraffins), and remaining aromatic hydrocarbons (including naphthalenes and alkylbenzenes).

There are different types of diesel such as low sulphur diesel depending upon the usage and need.

The synthetic diesel is produced from Bio Mass (BTL) and Bio diesel is produced from vegetable seeds.

the higher self ignition temperature of the petrol is due to the low density than the diesel.

as

density = pressure / (R* temperature)

R= universal gas constant.

ex. hydrogen (gas) has density = .082 at 300 k

while kerosene has =810

(both are in kg/m^3)

and auto ignition temperatures are

hydrogen =500

kreosene=295

similarly , petrol-density=737

diesel has=820 to 950 .