Adipic Acid Reaction Paper

.1.1 Adipic Acid

Adipic acid, also known as hexanedioic acid is a mildly toxic, white crystalline solid that is slightly soluble in water. It has a molecular formula of C6H10O4. The annual production rate of adipic acid worldwide is 2.5 million tons [1].

The majority of adipic acid produced is used as a precursor for manufacturing of nylon. In the pharmaceutical industry, adipic acid is used in the production of formulation matrix tables to obtain pH independent release for both weakly basic and acidic drugs [2].

1.2 Synthesis Routes

1.2.1 Current Industrial Standard

From the design brief, the raw material for this process must be biomass. The current industrial standard is the oxidation of a mixture of cyclohexanol and cyclohexanone, known

Many possible synthesis routes exist for bio based derivation; however they are limited mainly by their economic feasibility. A selection of routes is presented below.

1.2.2 Biological Synthesis using E.coli.

Genetically altered E.coli cells can convert glucose to cis, cis muconic acid [4] which is then hydrogenated to form adipic acid. Given that adipic acid must be produced in bulk, the cell cultures would not be feasible for such large volume processing. Secondly, this approach was not adopted due to the complexity in modelling the cell culture. No data was available for this task.

1.2.3 Hydrocarboxylation of γ-valerolactone

Hydrocarboxylation of γ-valerolactone (GVL) also produces adipic acid [5]. GVL can be synthesised via catalytic hydrogenation of levulinic acid [6], which itself is derived from cellulose. The

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primary reason this route was not chosen was inferior product yield. Approximately 60 % was obtained using carbon monoxide at 220oC.

1.2.4 Oxidation of

Sodium tungstate dihydrate is the catalyst. While yields and selectivity are quite high, there is a significant drawback to the process in a purification step. A liquid extraction using quaternary ammonium cations leads to a harmful environmental hazard. As one of the aims of bio-based adipic acid is to reduce environmental emissions this route was not chosen. Secondly, major difficulties were encountered in trying to find a biomass precursor to produce cyclohexene. This became far too complex and also contributed to this synthesis route being discarded.

1.2.5 Chosen Route: Conversion of Glucose

This route involves the conversion of glucose to glucaric acid and finally to adipic acid. Oxidations and hydrogenations are the basis of the chemical synthesis. Platinum and rhodium catalysts are used, and while expensive, do provide high product yields. This synthesis scheme is currently being up scaled by US firm Rennovia. It has been chosen as our synthesis route as it appears the most viable. A biomass source must be used as our precursor to glucose.

1.3 Biomass