Diisobutyl phthalate
Diisobutyl phthalate (DIBP) is prepared by esterification process of isobutanol and phthalic anhydride. Its structural formula is CH(COOCHCH(CH)). DIBP is an odorless plasticizer and has excellent heat and light stability. It is the lowest cost plasticizer for cellulose nitrate. DIBP has lower density and freezing point than the related compound dibutyl phthalate (DBP). Otherwise, it has similar properties DBP and can often be used as a substitute for it. Its refractive index is 1.488–1.492 (at 20 °C, D). Health issues. The concentration of a metabolite of DIBP, monoisobutyl phthalate (MIBP), has been steadily increasing in the urine  of Americans over the period 1999–2008. In 2021, DIBP, along with dextrorphan, was identified in >75% of sludge samples taken from 12 wastewater treatment plants in California. The same study associated this compound with estrogenic activity in vitro. Products in Taiwan made by Hebo Natural Products Limited (禾博天然產物有限公司) of China contained ginger contaminated with DIBP; 80,000 nutritional supplement capsules made with imported ginger powder were seized by the Public Health Department of Taiwan in June 2011. In addition, soybean extract and olive leaf extract, both in powder form, were contaminated with DIBP and DBP.