Indane sulfonate

The presence of some impurities, by-products of the process, can significantly affect the physical properties of the final product most important among them are the free oil (unconverted LAB), dialkyl sulfonates, sulfones, and bicyclic molecules (dialkyl tetralines and indanes). Sulfones which are formed when a too high sulfonation severity is applied... 

An interesting application of the conjugate addition of cm-bis(sulfone)s to enals has been reported by Palomo et al. [202] As depicted in Scheme 2.73, opticaUy active trisubstituted indanes can be prepared in good yields by a tandem Michael-Michael process employing cyclic gem-bis(sulfone) 130. 

The utility of the RBR in the synthesis of crovrded trisubstituted alkenes is demonstrated by the synthesis of ampelopsin D (Scheme 8.201. The thioether 48 was generated by acid-promoted cyclization of alcohol 46 and attack by thiol 47 on the benzylic cation. This conpound had a trans-relationship between the aryl branches on the indane system and was produced as a 1 1 mixture of epimers at the thioether linkage. In preparation for the RBR, the thioether 48 was oxidized to sulfone 49, which was treated with base and carbon tetrachloride to produce the RBR product 50 in 52% yield, along with 15% of its (Z)-isomer. Meyers conditions were found to be optimal for stereoselectivity in the RBR, with other methods producing poorer selectivity and unreliable results. The natural product ampelopsin D (51) was obtained after global deprotection with boron tribromide. 

Additional modifications to the Hantzsch 1,4-dihydropyridine synthesis generally involve the use of activated methylene compounds such as 1,3-diketones, co-cyanoacetophenone, co-phenylacetophenone, a, P-unsaturated ketones, and indane-l,3-diones. A number of efforts to improve reaction yields using eatalysts have also been reported, including the use of hydrotalcite materials, triphenylphosphine copper II triflate, and covalently anchored sulfonic acid on silica gel. Dihydropyridine synthesis has also recently been studied with high success using microwave and solvent-free" reaction conditions. 

The critical point connected with the use of LAS-sulfonic acid is represented by its tendency to undergo color increase dnring storage [12] and this sensitivity may depend on factors such as the LAB quality (i.e., iron, heavy alkylate, and DAT/indane content) as well as operating conditions adopted for its prodnction (i.e., SO3/LAB mole ratio, aging time, temperature, and hydrolysis conditions). Storage of the L AS-snlfonic acid should be preferably made in stainless steel tanks or carbon steel containers lined with epoxy resins and kept at a temperature not exceeding 30°C. 

Formylation and Carboj lation. Formylatlon of aromatic compounds such as benzene, toluene, xylenes, mesltylene, Indan, tetralin, and halobenzenes Is achieved In HSOsF-SbFs under atmospheric CO pressure at 0 °C (eq 19). However, In the cases of alkylbenzenes, both formylatlon and sulfonation took place under these reaction conditions to give alkylbenzaldehydes and formylalkylbenzenesulfonyl fluorides, as well as small amounts of alkylbenzenesulfonyl fluorides and bis (alkyIphenyl) sulfones. With benzene and halobenzenes, because of their lower reactivity only aldehydes were produced. 

Indane 36 was added dropwise to excess chlorosulfonic acid (4.5 equivalents) at -10 °C (3 hours) and gave a mixture of the 4- and 5-sulfonyl chlorides 37 and 38 in 76% yield (Equation 12). It was discovered that with increasing temperature the relative amount of indane-5-sulfonic acid increases at the expense of the 4-isomer. This is presumably because the 5-sulfonic acid is relatively less sterically hindered than the 4-acid and consequently is the more thermodynamically stable isomer. 

Linear alkylbenzene produced from chloroparaffms contains 6-8% dialkyltetralin and dialky lindane. Alkylbenzene produced from olefins contains about 1% of these compounds. Thus, LAS may contain about 1%, or about 7% of the sulfonated indanes and tetralins, with the indanes being at very low concentration compared to the tetralins. These byproducts are surfactants, and their presence is beneficial in liquid formulations since they act as hydrotropes and viscosity improvers. They can be determined by GC or GC/MS by the same methods as are used for determining the alkyl chain distribution. The compounds are made volatile by desulfonation or by derivatization as discussed in Chapter 8 (58,59). 

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