Alkylbenzene sulfonate

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The general structure of Sodium dodecylbenzenesulfonates, prominent examples of alkylbenzene sulphonates Natriumdodecylbenzolsulfonat.svg
The general structure of Sodium dodecylbenzenesulfonates, prominent examples of alkylbenzene sulphonates

Alkylbenzene sulfonates are a class of anionic surfactants, consisting of a hydrophilic sulfonate head-group and a hydrophobic alkylbenzene tail-group. Along with sodium laureth sulfate, they are one of the oldest and most widely used 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 ]

Contents

Branched alkylbenzene sulfonates

Alkylbenzenesulfonate BAS Structural Formula V1.svg
An example of a branched alkylbenzene sulfonate (BAS)
"WATER STINKS," WRITES THE PHOTOGRAPHER ABOUT THIS SCENE - NARA - 544681.jpg
Extensive foaming Fremont, California - 1972

Branched alkylbenzene sulfonates (BAS) were introduced in the early 1930s and saw significant growth from the late 1940s onwards, [3] in early literature these synthetic detergents are often abbreviated as syndets. They were prepared by the Friedel–Crafts alkylation of benzene with 'propylene tetramer' (also called tetrapropylene) followed by sulfonation. Propylene tetramer being a broad term for a mixture of compounds formed by the oligomerization of propene, its use gave a mixture of highly branched structures. [4]

Compared to traditional soaps, BAS offered superior tolerance to hard water and better foaming. [5] However, the highly branched tail made it difficult to biodegrade. [6] BAS was widely blamed for the formation of large expanses of stable foam in areas of wastewater discharge such as lakes, rivers and coastal areas (sea foams), as well as foaming problems encountered in sewage treatment [7] and contamination of drinking water. [8] As such, BAS was phased out of most detergent products during the 1960s, being replaced with linear alkylbenzene sulfonates (LAS), which biodegrade much more rapidly. BAS is still important in certain agrochemical and industrial applications, where rapid biodegradability is of reduced importance. For instance, inhibiting asphaltene deposition from crude oil.

Linear alkylbenzene sulfonates

An example of a linear alkylbenzene sulfonate (LAS) Alkylbenzenesulfonate LAS Structural Formula V1.svg
An example of a linear alkylbenzene sulfonate (LAS)

Linear alkylbenzene sulfonates (LAS) are prepared industrially by the sulfonation of linear alkylbenzenes (LABs), which can themselves be prepared in several ways. [2] In the most common route benzene is alkylated by long chain monoalkenes (e.g. dodecene) using hydrogen fluoride as a catalyst. [9] The purified dodecylbenzenes (and related derivatives) are then 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 alkenes rather than the final product, perfectly linear addition products are not seen, in-line with Markovnikov's rule. Thus, the alkylation of linear alkenes, even 1-alkenes such as 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, [13] [14] however their physical properties (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.

Related Research Articles

<span class="mw-page-title-main">Detergent</span> Surfactants with cleansing properties

A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are more soluble in hard water, because the polar sulfonate is less likely than the polar carboxylate to bind to calcium and other ions found in hard water.

<span class="mw-page-title-main">Surfactant</span> Substance that lowers the surface tension between a liquid and another material

Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word "surfactant" is a blend of surface-active agent, coined c. 1950. As they consist of a water-repellent and a water-attracting part, they enable water and oil to mix; they can form foam and facilitate the detachment of dirt.

<span class="mw-page-title-main">Alkylation</span> Transfer of an alkyl group from one molecule to another

Alkylation is a chemical reaction that entails transfer of an alkyl group. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene. Alkylating agents are reagents for effecting alkylation. Alkyl groups can also be removed in a process known as dealkylation. Alkylating agents are often classified according to their nucleophilic or electrophilic character. In oil refining contexts, alkylation refers to a particular alkylation of isobutane with olefins. For upgrading of petroleum, alkylation produces a premium blending stock for gasoline. In medicine, alkylation of DNA is used in chemotherapy to damage the DNA of cancer cells. Alkylation is accomplished with the class of drugs called alkylating antineoplastic agents.

In organic chemistry, ethoxylation is a chemical reaction in which ethylene oxide adds to a substrate. It is the most widely practiced alkoxylation, which involves the addition of epoxides to substrates.

In organic chemistry, hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes from alkenes. This chemical reaction entails the net addition of a formyl group and a hydrogen atom to a carbon-carbon double bond. This process has undergone continuous growth since its invention: production capacity reached 6.6×106 tons in 1995. It is important because aldehydes are easily converted into many secondary products. For example, the resultant aldehydes are hydrogenated to alcohols that are converted to detergents. Hydroformylation is also used in speciality chemicals, relevant to the organic synthesis of fragrances and pharmaceuticals. The development of hydroformylation is one of the premier achievements of 20th-century industrial chemistry.

<span class="mw-page-title-main">Sulfonic acid</span> Organic compounds with the structure R−S(=O)2−OH

In organic chemistry, sulfonic acid refers to a member of the class of organosulfur compounds with the general formula R−S(=O)2−OH, where R is an organic alkyl or aryl group and the S(=O)2(OH) group a sulfonyl hydroxide. As a substituent, it is known as a sulfo group. A sulfonic acid can be thought of as sulfuric acid with one hydroxyl group replaced by an organic substituent. The parent compound is the parent sulfonic acid, HS(=O)2(OH), a tautomer of sulfurous acid, S(=O)(OH)2. Salts or esters of sulfonic acids are called sulfonates.

A fabric softener or fabric conditioner is a conditioner that is applied to laundry after it has been washed in a washing machine. A similar, more dilute preparation meant to be applied to dry fabric is known as a wrinkle releaser.

<span class="mw-page-title-main">Polystyrene sulfonate</span> Drug class

Polystyrene sulfonates are a group of medications used to treat high blood potassium. Effects generally take hours to days. They are also used to remove potassium, calcium, and sodium from solutions in technical applications.

<span class="mw-page-title-main">Terminal alkene</span> Hydrocarbon compounds with a C=C bond at the alpha carbon

In organic chemistry, terminal alkenes are a family of organic compounds which are alkenes with a chemical formula CxH2x, distinguished by having a double bond at the primary, alpha (α), or 1- position. This location of a double bond enhances the reactivity of the compound and makes it useful for a number of applications.

<span class="mw-page-title-main">Laundry detergent</span> Type of detergent used for cleaning laundry

Laundry detergent is a type of detergent used for cleaning dirty laundry (clothes). Laundry detergent is manufactured in powder and liquid form.

<span class="mw-page-title-main">Isethionic acid</span> Chemical compound

Isethionic acid is an organosulfur compound containing an alkylsulfonic acid located beta to a hydroxy group. Its discovery is generally attributed to Heinrich Gustav Magnus, who prepared it by the action of solid sulfur trioxide on ethanol in 1833. It is a white water-soluble solid used in the manufacture of certain surfactants and in the industrial production of taurine. It is most commonly available in the form of its sodium salt.

Lignosulfonates (LS) are water-soluble anionic polyelectrolyte polymers: they are byproducts from the production of wood pulp using sulfite pulping. Most delignification in sulfite pulping involves acidic cleavage of ether bonds, which connect many of the constituents of lignin. Sulfonated lignin (SL) refers to other forms of lignin by-product, such as those derived from the much more popular Kraft process, that have been processed to add sulfonic acid groups. The two have similar uses and are commonly confused with each other, with SL being much cheaper. LS and SL both appear as free-flowing powders; the former is light brown while the latter is dark brown.

<span class="mw-page-title-main">Organosulfate</span> Organic compounds of the form R–O–SO₃ (charge –1)

In organosulfur chemistry, organosulfates are a class of organic compounds sharing a common functional group with the structure R−O−SO−3. The SO4 core is a sulfate group and the R group is any organic residue. All organosulfates are formally esters derived from alcohols and sulfuric acid although many are not prepared in this way. Many sulfate esters are used in detergents, and some are useful reagents. Alkyl sulfates consist of a hydrophobic hydrocarbon chain, a polar sulfate group and either a cation or amine to neutralize the sulfate group. Examples include: sodium lauryl sulfate and related potassium and ammonium salts.

Dodecylbenzene is an organic compound with the formula C
12H
25C
6H
5. Dodecylbenzene is a colorless liquid with a weak oily odor that floats on water.

Cleavable detergents, also known as cleavable surfactants, are special surfactants (detergents) that are used in biochemistry and especially in proteomics to enhance protein denaturation and solubility. The detergent is rendered inactive by cleavage, usually under acidic conditions, in order to make the sample compatible with a following procedure or in order to selectively remove the cleavage products.

<span class="mw-page-title-main">Linear alkylbenzene</span> Chemical compound

Linear alkylbenzenes (sometimes also known as LABs) are a family of organic compounds with the formula C6H5CnH2n+1. Typically, n lies between 10 and 16, although generally supplied as a tighter cut, such as C12-C15, C12-C13 and C10-C13, for detergent use. The CnH2n+1 chain is unbranched. They are mainly produced as intermediate in the production of surfactants, for use in detergent. Since the 1960s, LABs have emerged as the dominant precursor of biodegradable detergents.

A methylene blue active substances assay, or MBAS assay, is a colorimetric analysis test method that uses methylene blue to detect the presence of anionic surfactants in a sample of water. An anionic surfactant detected by the color reaction is called a methylene blue active substance (MBAS).

<span class="mw-page-title-main">Alkylbenzene</span> Family of organic compounds

An alkylbenzene is a chemical compound that contains a monocyclic aromatic ring attaching to one or more saturated hydrocarbon chains. Alkylbenzenes are derivatives of benzene, in which one or more hydrogen atoms are replaced by alkyl groups. The simplest member, toluene, has the hydrogen atom of the benzene ring replaced by a methyl group. The chemical formula of alkylbenzenes is CnH2n-6.

Wastewater comes out of the laundry process with additional energy (heat), lint, soil, dyes, finishing agents, and other chemicals from detergents. Some laundry wastewater goes directly into the environment, due to the flaws of water infrastructure. The majority goes to sewage treatment plants before flowing into the environment. Some chemicals remain in the water after treatment, which may contaminate the water system. Some have argued they can be toxic to wildlife, or can lead to eutrophication.

α-Olefin sulfonate Class of chemical compounds

α-Olefin sulfonates are a group of anionic surfactants, which are used as detergents. The compounds contain a - mostly linear, primary - alkyl R and a monovalent cation M, preferably sodium. The most frequently used example of this group of substances is sodium α-olefin sulfonate.

References

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  2. 1 2 Kocal, Joseph A; Vora, Bipin V; Imai, Tamotsu (November 2001). "Production of linear alkylbenzenes". Applied Catalysis A: General. 221 (1–2): 295–301. doi:10.1016/S0926-860X(01)00808-0.
  3. ↑ Dee, Foster; Snell, Cornelia T. (August 1958). "50th ANNIVERSARY FEATURE—Fifty Years of Detergent Progress". Industrial & Engineering Chemistry. 50 (8): 48A–51A. doi:10.1021/ie50584a005.
  4. ↑ Scheibel, Jeffrey J. (17 December 2015). "The evolution of anionic surfactant technology to meet the requirements of the laundry detergent industry". Journal of Surfactants and Detergents. 7 (4): 319–328. doi:10.1007/s11743-004-0317-7. S2CID   93889318.
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  6. 1 2 Hashim, M. A.; Kulandai, J.; Hassan, R. S. (24 April 2007). "Biodegradability of branched alkylbenzene sulphonates". Journal of Chemical Technology & Biotechnology. 54 (3): 207–214. doi:10.1002/jctb.280540302.
  7. ↑ McKinney, Ross E. (1957). "Syndets and Waste Disposal". Sewage and Industrial Wastes. 29 (6): 654–666. JSTOR   25033358.
  8. ↑ Sawyer, Clair N.; Ryckman, Devere W. (1957). "Anionic Synthetic Detergents and Water Supply Problems". American Water Works Association. 49 (4): 480–490. Bibcode:1957JAWWA..49d.480S. doi:10.1002/j.1551-8833.1957.tb16814.x. JSTOR   41254845.
  9. ↑ Cahn, AOCS]. Ed.: Arno (2003). 5th World Conference on Detergents: Reinventing the industry - opportunities and challenges ([Elektronische Ressource] ed.). Champaign, Ill.: AOCS Press. ISBN   1-893997-40-5.
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  11. ↑ Bipin V. Vora; Joseph A. Kocal; Paul T. Barger; Robert J. Schmidt; James A. Johnson (2003). "Alkylation". Kirk-Othmer Encyclopedia of Chemical Technology. doi:10.1002/0471238961.0112112508011313.a01.pub2. ISBN   0471238961.
  12. ↑ Matheson, K. Lee (August 1985). "Detergency performance comparison between LAS and ABS using calcium sulfonate precipitation boundary diagrams". Journal of the American Oil Chemists' Society. 62 (8): 1269–1274. doi:10.1007/BF02541841. S2CID   98677989.
  13. ↑ Matheson, K. Lee; Matsoim, Ted P. (September 1983). "Effect of carbon chain and phenyl isomer distribution on use properties of linear alkylbenzene sulfonate: A comparison of 'high' and 'low' 2-phenyl LAS homologs". Journal of the American Oil Chemists' Society. 60 (9): 1693–1698. doi:10.1007/BF02662436. S2CID   97659271.
  14. ↑ Baumgartner, F. N. (June 1954). "Relation of Molecular Structure to Detergency of Some Alkylbenzene Sulfonates". Industrial & Engineering Chemistry. 46 (6): 1349–1352. doi:10.1021/ie50534a061.
  15. ↑ Drozd, Joseph C.; Gorman, Wilma (March 1988). "Formulating characteristics of high and low 2-phenyl linear alkylbenzene sulfonates in liquid detergents". Journal of the American Oil Chemists' Society. 65 (3): 398–404. doi:10.1007/BF02663085. S2CID   93127857.
  16. ↑ Sweeney, W. A.; Olson, A. C. (December 1964). "Performance of straight-chain alkylbenzene sulfonates (LAS) in heavy-duty detergents". Journal of the American Oil Chemists' Society. 41 (12): 815–822. doi:10.1007/BF02663964. S2CID   98586085.
  17. ↑ Farn, Richard J. (2006). Chemistry and technology of surfactants . Oxford: Blackwell Pub. p.  96. ISBN   978-14051-2696-0.
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  19. ↑ Mackay, Donald; Di Guardo, Antonio; Paterson, Sally; Kicsi, Gabriel; Cowan, Christina E.; Kane, David M. (September 1996). "Assessment of chemical fate in the environment using evaluative, regional and local-scale models: Illustrative application to chlorobenzene and linear alkylbenzene sulfonates". Environmental Toxicology and Chemistry. 15 (9): 1638–1648. doi:10.1002/etc.5620150930.
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