Sentence:  These widely advertised products , which are used primarily for washing clothes , are based on high-sudsing , synthetic organic actives ( sodium <WSD>alkylbenzenesulfonates</WSD> ) and contain up to 50 % by weight of sodium tripolyphosphate or a mixture of sodium tripolyphosphate and tetrasodium pyrophosphate . 
Meaning of the word marked with <WSD> tags:  sulfonate of alkyl benzene