Rufus T. Firefly wrote:webenda wrote:The broad definition of organic chemistry is that it is the chemistry of carbon containing substances. But an exception is always made in the definition: The carbonates, CO2 and metal cyanides are specifically excluded from organic chemistry.
That definition may be somewhat dated and CO2 being excluded is a bit odd as it's a classic means to make carboxylic acids through organic chem that learned in the lab better than 40 years ago. In fact, the lines defining the borders of organic chem are quite blurry.
It is an old definition, no longer used, except for a few ancient individuals, (Murph still uses it.) I was pointing out that even the older definition had exclusions, CO2 being one of them.
Although carbon dioxide contains carbon and has covalent bonds, it also fails the older test for whether or not a compound could be considered organic: Could the compound be produced from inorganic sources? Carbon dioxide occurs naturally from processes that are definitely not organic. It is released from volcanoes, minerals, and other inanimate sources. The case of carbon dioxide, yes, living organisms produce it, but so do many other natural processes. Thus, it is classified as inorganic.
This older definition of "organic" fell apart when chemists started to synthesize organic compounds from inorganic sources. For example, Wohler made urea (an organic) from ammonium chloride and potassium cyanate. And petroleum (an organic) comes from limestone and water, both inorganic.
More on why carbon dioxide isn't considered to be an organic compound: Organic molecules don't just contain carbon. They contain hydrocarbons or carbon bonded to hydrogen. So, when you're determining whether a carbon compound is organic or not, look to see whether it contains hydrogen in addition to carbon and whether the carbon is bonded to the hydrogen. Make sense?
Carbon dioxide isn't the only compound that contains carbon but isn't organic. Other examples include carbon monoxide (CO), Calcium Carbonate (CaCO3), sodium bicarbonate, iron cyanide complexes, and carbon tetrachloride. As you might expect, elemental carbon isn't organic either.
Amorphous carbon, buckminsterfullerene, graphite, and diamond are all inorganic.
Elemental analysis of coal gives empirical formulas such as C137H97O9NS for bituminous coal and C240H90O4NS for high-grade anthracite. Coal has the carbon/hydrogen bond and is therefore organic, no matter what geologists want it to be.
I don't mind CO2 but C137H97O9NS just looks wrong. Here it are the coal formulae as an image.