Secondary phosphites sulfides

Salts of dithiocarbamic acid can be prepared by the addition of primary or secondary amines to carbon disulfide. This reaction is similar to 16-9. Hydrogen sulfide can be eliminated from the product, directly or indirectly, to give isothiocyanates (RNCS). Isothiocyanates can be obtained directly by the reaction of primary amines and CS2 in pyridine in the presence of DCC. ° In the presence of diphenyl phosphite and pyridine, primary amines add to CO2 and to CS2 to give, respectively, symmetrically substituted ureas and thioureas ... 

Kellum [115] has described a class-selective oxidation chemistry procedure for the quantitative determination of secondary antioxidants in extracts of PE and PP with great precision (better than 1 %). Diorgano sulfides and tertiary phosphites can be quantitatively oxidised with /-chloropcroxybenzoic acid to the corresponding sulfones and phosphates with no interference from other stabilisers or additives. Hindered phenols, benzophenones, triazoles, fatty acid amides, and stearate... 

Secondary antioxidants or hydroperoxide decomposers (see Scheme 2.1) are typified by organosulfur species having reducing properties such as sulfides and thioethers. Tertiary phosphites also fall into this category (see Scheme 2.9). 

Thiophilic agents, such as trimethyl phosphite, phosphorous triamides, secondary amides (piperidine, diethylamine) or anionic thioderivatives (thiophenoxide, sodium sulfide) are commonly used2. They differ in their efficiency of trapping the sulfenate ester in the following order1 ... 

Aromatic amines are not able to deactivate ROOH. The effect may be reached in PO, PUR or diene based elastomers with heterosynergistic combinations of amines with secondary AO like organic phosphites or sulfides. 

To stabilize PO s against degradation during the melt processing, antioxidants (e.g., hindered phenols, sulfide esters, organic phosphites, secondary aromatic amines, and hindered amines), peroxide decomposers (usually a phosphite) and frequently acid acceptors (e.g., calcium stearate) are used. For special applications metal deactivators are also added. 

Secondary antioxidants, often called peroxide decomposers, also may be further categorised as stoichiometric peroxide decomposers and catalytic peroxide decomposers. The former are represented by, for example, phosphites the latter by organic sulfides and their transformation products. 

Another type of antioxidant sacrificially reacts with oxygen, probably in the form of a peroxide. This type of antioxidant is often called a secondary antioxidant. Commonly they are used in conjunction with a primary antioxidant such as a hindered phenol. They are typically phosphites, which upon reaction with oxygen become phosphates or sulfides that can react with oxygen to form sulfoxides or sulfones, depending on the degree of oxidation. The same concerns about polymer compatibility and volatility apply here also. 

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