Irganox 1010 antioxidant structure

Figures 10 and 11 show the structure of the hindered phenolic antioxidant Irganox 1010 (Ciba) and its negative ion APCI mass spectra, respectively. Separation was achieved under the following LC conditions Column Aqua Cl 8 (Phenomenex) 3 pm, 150x2.00 mm, 15% carbon loading, proprietary end capping. Column Temp 50°C. Injection volume 5 pi.

A hindered phenol commonly used as an antioxidant is 2,6-di-terf-butyl-4-meth-ylphenol (also known as butylated hydroxy toluene or "BHT"). Structures of BHT and other hindered phenol antioxidants are shown in Figure 8.3. Many of these complex structures have lengthy lUPAC names and are frequently called by trade names assigned by manufacturers, e.g., Irganox 1135 from Ciba (now BASF). 

Scheme 12.8 Structure of Irganox 1010 having the most pronounced antioxidant efSciency...

The response of polyurethanes to thermally activated autoxidation depends upon polymer structure. In general, polyurethane degradation by this mechanism is suppressed by the addition of antioxidant to the polymer. Ultraviolet initiated autoxidation is suppressed by a suitable screen (e.g. carbon black, titanium dioxide) or a combination of antioxidant and ultraviolet absorber. Irganox 1010 and Tinuvin P (Ciba-Geigy) are particularly suitable antioxidant and ultraviolet absorbers, respectively, for polyurethanes. Polyurethane structures with enhanced resistance to ultraviolet initiated autoxidation may be possible. 

The result of both practical and legislative pressures is that most commercial antioxidants contain the active functions incorporated into structures designed to reduce their mobility and volatility and/or to increase their solubility in the polymer. Two main strategies are adopted. The first is to couple several antioxidant functions into an oligomeric molecule, probably the best example being the tetrafunctional antioxidant Irganox 1010 (Ciba Specialty Chemicals )... 

The Cyasorb UV 2908 is a p-alkyl-substituted hydroxybenzoate of structure (21), while the Irganox 1076 is a hindered phenol and Weston 618 is triphenyl phosphite. The latter additives are antioxidants used for process stability and here the reader should refer to Volume 6, Chapter 18 and refs. 3 and 5. 

AO-1 and AO-2 are by far the most broadly used phenolic antioxidants. Nevertheless, several further derivatives are available in the market, such as AO-4 (brand names Irganox 3114 (BASF), Hostanox O 14 (Clariant)), based on a cyclic structural element. 

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