Production of Neopentyl Glycol Higher Yield by Internal Recycling

Production of Neopentyl Glycol Higher Yield by Internal Recycling [75], [103], [104] 

In the process for producing neopentyl glycol (2,2-dimethyl-l,3-propanediol) a joint product is formed and some starting materials remain unreacted. The latter are internally recycled to the process with the aid of the coupled products. 

The first reaction, in reactor 1, is an aldol condensation in which formaldehyde is reacted with isobutyraldehyde (2-methylpropanal) in an alkaline medium with tri-n-propylamine as the catalyst to form hydroxypivalaldehyde (3-hydroxy-2,2-dimethylpro-panal). 

Neopentyl glycol and isobutanol are separated by distillation. Some of the recovered isobutanol is used to extract the aqueous phase formed in the aldol condensation, and the remainder is used to produce synthesis gas. The isobutanol extract contains hydroxypivalaldehyde and starting materials. It is therefore recycled to the aldol condensation reactor. The isobutanol transferred into reactor 1 then enters reactor 2 via the organic phase. This leads to an increase in the amount of isohutanol so that, after separation by distillation, some of the isobutanol can be used to produce synthesis gas. Wastewater from the bottom of the extraction column is fractionated. The low-boiling compounds formed as overhead products are also used to produce synthesis gas (Fig. 25). Wastewater from the fractionating column is treated in the biological waste-water treatment plant. 

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