Alkylbenzene sulfonate

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(Redirected from
Sodium dodecylbenzenesulfonate
)
The general structure of Sodium dodecylbenzenesulfonates, prominent examples of alkylbenzene sulphonates

Alkylbenzene sulfonates are a class of

synthetic detergents and may be found in numerous personal-care products (soaps, shampoos, toothpaste etc.) and household-care products (laundry detergent, dishwashing liquid, spray cleaner etc.).[1]
They were introduced in the 1930s in the form of branched alkylbenzene sulfonates (BAS). However following environmental concerns these were replaced with linear alkylbenzene sulfonates (LAS) during the 1960s.[2] Since then production has increased significantly from about one million tons in 1980, to around 3.5 million tons in 2016, making them most produced anionic surfactant after soaps.[citation needed]

Branched alkylbenzene sulfonates

An example of a branched alkylbenzene sulfonate (BAS)
Extensive foaming Fremont, California - 1972

Branched alkylbenzene sulfonates (BAS) were introduced in the early 1930s and saw significant growth from the late 1940s onwards,

propene, its use gave a mixture of highly branched structures.[4]

Compared to traditional soaps, BAS offered superior tolerance to

crude oil
.

Linear alkylbenzene sulfonates

An example of a linear alkylbenzene sulfonate (LAS)

Linear alkylbenzene sulfonates (LAS) are prepared industrially by the

sulfonated with sulfur trioxide to give the sulfonic acid.[10] The sulfonic acid is subsequently neutralized with sodium hydroxide.[1]
The term "linear" refers to the starting
1-dodecene, gives several isomers of phenyldodecane.[11]

Structure property relationships

Under ideal conditions the cleaning power of BAS and LAS is very similar, however LAS performs slightly better in normal use conditions, due to it being less affected by hard water.[12] Within LAS itself the detergency of the various isomers are fairly similar,

Krafft point, foaming etc.) are noticeably different.[15][16]
In particular the Krafft point of the high 2-phenyl product (i.e. the least branched isomer) remains below 0 °C up to 25% LAS whereas the low 2-phenyl cloud point is ~15 °C.[17] This behavior is often exploited by producers to create either clear or cloudy products.

Environmental fate

The biodegradability of alkylbenzene sulfonates has been well studied,[6][18][19] and is affected by isomerization, in this case, branching. The salt of the linear material has an LD50 of 2.3 mg/liter for fish, about four times more toxic than the branched compound; however the linear compound biodegrades far more quickly, making it the safer choice over time. It is biodegraded rapidly under aerobic conditions with a half-life of approximately 1–3 weeks;[18] oxidative degradation initiates at the alkyl chain.[1] Under anaerobic conditions it degrades very slowly or not at all, causing it to exist in high concentrations in sewage sludge, but this is not thought to be a cause for concern as it will rapidly degrade once returned to an oxygenated environment.

References

  1. ^
    doi:10.1002/14356007.a25_747
  2. ^
    doi:10.1016/S0926-860X(01)00808-0
    .
  3. doi:10.1021/ie50584a005
    .
  4. S2CID 93889318
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  5. doi:10.1111/j.1478-4408.1947.tb02430.x
    .
  6. ^
    doi:10.1002/jctb.280540302
    .
  7. JSTOR 25033358
    .
  8. JSTOR 41254845
    .
  9. ISBN 1-893997-40-5
    .
  10. doi:10.1021/op9700439
    .
  11. ISBN 0471238961
    .
  12. S2CID 98677989
    .
  13. S2CID 97659271
    .
  14. doi:10.1021/ie50534a061
    .
  15. S2CID 93127857
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  16. S2CID 98586085
    .
  17. ISBN 978-14051-2696-0
    .
  18. ^
    PMID 10085562
    .
  19. doi:10.1002/etc.5620150930
    .
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