Help a fellow chemist out here, I’m drawing a complete blank. Could somebody provide a hint about the actual, molecular composition of diesel fuel?


My new car runs on it and I want to know what it is. To begin with, I can’t even find a satisfactory and unambiguous definition of diesel. It is unlisted in the Merck Index and Wikipedia says diesel fuel can be many different things. Come on! You can find many pages like this, but where are the hard facts? Petrochemists, step forth.

Gasoline (UK: petrol) is easier to get a decent picture of. There is a bulk of short and saturated hydrocarbons (C4-C12), topped up with a some MTBE, a little bit of ethanol and a dash of aromatics (toluene-ish compounds).

I would love it if someone was able to explain diesel fuel to me using a similar nomenclature. In other words, show me the goddamn structures – CAS numbers on the table, now!


12 Responses to Diesel fuel? Seriously.

  1. Dan Foerster says:

    Coming straight off Wikipedia:
    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

    From there, I followed the reference to this:

    Which has your table.

  2. drfreddy says:

    OMG… Thank you very much.

    Uh, case closed I guess. After 40 minutes or so 🙂

  3. CatalysisAlex says:
    It’s a German page, but it contains all to satisfy it needs, including a CAS number !

  4. Billy Diol says:


    CAS: 68476-34-6

    Main ingredient: Dinosaur

    Production: Dig a really really deep hole. Add dinosaurs and let sit for about 100 000 years. Distill.


  5. Angel says:

    The composition also varies depending on in what country it is meant to be used in. I mean climate etc. affects what properties that are desirable.

  6. milkshake says:

    diesel engines are not that picky: the first ones (made by Diesel) run on pure peanut oil. Since glycerol-derived decomposition products generate tar deposits over in the engne, nowadays they used fatty acid methyl esters obtained by transesterification of (low-quality) vegetable oils as a “biodiesel”. Biodiesel is great if you have cheap source of used oil (Mc Donalds) to start with and worry about water pollution from a diesel fuel spill in a sensitive environment but it might not be good choice in your latitudes in the winter time because biodiesel easily freezes into a wax sludge.

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