Succinic acid produced using petrochemical resources is derived from maleic anhydride,which is produced from n-butane through oxidation over vanadium-phosphorous oxide catalysts
[Liu et al., 2008, Gascon et al., 2006]. A simplified reaction pathway of n-butane to maleic anhydride is shown below in Figure 2-2.

The reaction from maleic anhydride to succinic acid begins by hydrolysis, breaking one of the single bonds between carbon and oxygen, forming maleic acid. The addition of hydrogen breaks the carbon-carbon double bond and completes the reaction, forming succinic acid.
Succinic acid produced from fossil fuels is what gives it the distinction of not being a natural product [Song and Lee, 2006]. While this method of production is currently cheaper than processing by fermentation, there are some very large drawbacks [Wan et al., 2008]. As the term petrochemical processing implies, succinic acid is made using non-renewable resources such as natural gas which will become more difficult to find as time passes. As this raw material becomes harder to locate and demand continues to increase, it will become increasingly expensive [Isar etal., 2006]. In addition, the removal of oil and gas from deposits, transportation and processing require a lot of energy and generate a large amount of emissions [McKinlay et al, 2007]. This process is not sustainable in the long term and another solution is required if industries want to
continue producing succinic acid with increasing demand [Wan et al, 2008].