Organosulfate
Encyclopedia
Organosulfates are a class of organic compounds sharing a common functional group
commonly with the structure R-O-SO3-. The SO4 core is a sulfate
group and the R group is any organic residue. All organosulfates are formally ester
s derived from alcohol
s and sulfuric acid
, although many are not prepared in this way. Many sulfate esters are used in detergents, and some are useful reagent
s. Alkyl sulfates consist of a hydrophobic
hydrocarbon chain, a polar sulfate
or sulfonate
group (containing an anion) and either a cation or amine
to neutralize the sulfate group. Examples include: sodium lauryl sulfate (also known as sulfuric acid mono dodecyl ester sodium salt) and related potassium and ammonium salts.
in liquid soaps, detergents to clean wool, surface cleaners, as active ingredients in laundry detergents, shampoos and conditioners. They can also be found in other household products such as toothpastes, antacids, cosmetics and foods. Generally they are found in consumer products at concentrations ranging from 3-20%. In 2003 approximately 118,000 t/a of alkyl sulfates were used in the U.S.
fatty alcohols such as those derived from lauryl alcohol. An example is sodium laureth sulfate
, an ingredient in some cosmetics
.
feedstock or the Ziegler process, the hydrocarbon
chain of the alcohol will be linear. If derived using the oxo process, a low level of branching will appear usually with a methyl or ethyl group at the C-2 position, containing even and odd amounts of alkyl chains. These alcohols react with chlorosulfuric acid
:
Some organosulfates can be prepared by the Elbs persulfate oxidation
of phenols and the Boyland-Sims oxidation
of anilines.
and dimethyl sulfate
, colourless liquids that are used as reagent
s in organic synthesis
. These compounds are potentially dangerous alkylating agents.
(PAPS). Sulfate is an inert anion, so nature activates it by the formation of these ester derivatives, which are susceptible to reduction to sulfite. Many organisms utilize these reactions for metabolic purposes or for the biosynthesis
of sulfur compounds required for life.
Laboratory studies have not found alkyl sulfates to be genotoxic, mutagenic
or carcinogenic
. No long term reproductive effects have been found.
. Invertebrates were found to be the most sensitive trophic group to alkyl sulfates. Sodium laurylsulfate tested on Uronema parduczi, a protozoan, was found to have the lowest effect value with the 20 h-EC5 being 0.75 mg/l. Chronic exposure tests with C12 to C18 with the invertebrate Ceriodaphnia dubia found the highest toxicity is with C14 (NOEC was 0.045mg/l).
In terms of thermal stability, alkyl sulfates degrade well before reaching their boiling point due to low vapor pressure (for C8-18 from 10-11 to 10-15 hPa). Soil sorption is proportional to carbon chain length, with a length of 14 and more having the highest sorption rate. Soil concentrations have been found to vary from 0.0035 to 0.21 mg/kg dw.
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
commonly with the structure R-O-SO3-. The SO4 core is a sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
group and the R group is any organic residue. All organosulfates are formally ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
s derived from alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
s and sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
, although many are not prepared in this way. Many sulfate esters are used in detergents, and some are useful reagent
Reagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...
s. Alkyl sulfates consist of a hydrophobic
Hydrophobe
In chemistry, hydrophobicity is the physical property of a molecule that is repelled from a mass of water....
hydrocarbon chain, a polar sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
or sulfonate
Sulfonate
A sulfonate is a salt or ester of a sulfonic acid. It contains the functional group R-SO2O-.- Sulfonate salts:Anions with the general formula RSO2O− are called sulfonates. They are the conjugate bases of sulfonic acids with formula RSO2OH. As sulfonic acids tend to be strong acids, the...
group (containing an anion) and either a cation or amine
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
to neutralize the sulfate group. Examples include: sodium lauryl sulfate (also known as sulfuric acid mono dodecyl ester sodium salt) and related potassium and ammonium salts.
Applications
Alkyl sulfates are commonly used as an anionic surfactantSurfactant
Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...
in liquid soaps, detergents to clean wool, surface cleaners, as active ingredients in laundry detergents, shampoos and conditioners. They can also be found in other household products such as toothpastes, antacids, cosmetics and foods. Generally they are found in consumer products at concentrations ranging from 3-20%. In 2003 approximately 118,000 t/a of alkyl sulfates were used in the U.S.
Synthetic organosulfates
A common example is sodium lauryl sulfate, with the formula CH3(CH2)11OSO3Na. Also common in consumer products are the sulfate esters of ethoxylatedEthoxylation
Ethoxylation is an industrial process in which ethylene oxide is added to alcohols and phenols to give surfactants. The invention of the process is attributed to Schöller and Wittwer at I.G. Farben industrie.-Production:...
fatty alcohols such as those derived from lauryl alcohol. An example is sodium laureth sulfate
Sodium laureth sulfate
Sodium laureth sulfate, or sodium lauryl ether sulfate , is a detergent and surfactant found in many personal care products . SLES is an inexpensive and very effective foaming agent. SLES, SLS and ALS are surfactants that are used in many cosmetic products for their cleansing and emulsifying...
, an ingredient in some cosmetics
Cosmetics
Cosmetics are substances used to enhance the appearance or odor of the human body. Cosmetics include skin-care creams, lotions, powders, perfumes, lipsticks, fingernail and toe nail polish, eye and facial makeup, towelettes, permanent waves, colored contact lenses, hair colors, hair sprays and...
.
Preparation
Alkylsulfate can be produced from alcohols, which in turn are obtained by hydrogenation of animal or vegetable oils and fats or using the Ziegler process or through oxo synthesis. If produced from oleochemicalOleochemical
Oleochemicals are chemicals derived from plant and animal fats. They are analogous to petrochemicals derived from petroleum.The formation of basic oleochemical substances like fatty acids, fatty acid methyl esters , fatty alcohols, fatty amines and glycerols are by various chemical and enzymatic...
feedstock or the Ziegler process, the hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....
chain of the alcohol will be linear. If derived using the oxo process, a low level of branching will appear usually with a methyl or ethyl group at the C-2 position, containing even and odd amounts of alkyl chains. These alcohols react with chlorosulfuric acid
Chlorosulfuric acid
Chlorosulfuric acid is the inorganic compound with the formula HSO3Cl. It is also known as chlorosulfonic acid. It is a distillable, colorless liquid that should be handled with care. It is a hygroscopic and a powerful lachrymator.-Structure and properties:Chlorosulfuric acid is a tetrahedral...
:
- ClSO3H + ROH → ROSO3H + HCl
Some organosulfates can be prepared by the Elbs persulfate oxidation
Elbs persulfate oxidation
The Elbs persulfate oxidation is the organic reaction of phenols with alkaline potassium persulfate to form para-diphenols.Several reviews have been published.-Reaction mechanism:...
of phenols and the Boyland-Sims oxidation
Boyland-Sims oxidation
The Boyland-Sims oxidation is the chemical reaction of anilines with alkaline potassium persulfate, which after hydrolysis forms ortho-hydroxyl anilines.The ortho-isomer is formed predominantly...
of anilines.
Dialkylsulfates
A less common family of organosulfates have the formula R-O-SO2-O-R'. They are prepared from sulfuric acid and the alcohol. The main examples are diethyl sulfateDiethyl sulfate
Diethyl sulfate is a highly toxic and likely carcinogenicchemical compound with formula 24. It occurs as a colorless liquid with a peppermint odor.Diethyl sulfate is used as an alkylating agent to prepare ethyl derivatives of phenols, amines, and thiols....
and dimethyl sulfate
Dimethyl sulfate
Dimethyl sulfate is a chemical compound with formula 2SO2. As the diester of methanol and sulfuric acid, its formula is often written as 2SO4 or even Me2SO4, where CH3 or Me is methyl...
, colourless liquids that are used as reagent
Reagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...
s in organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
. These compounds are potentially dangerous alkylating agents.
Natural sulfate esters
The reduction of sulfate in nature involves the formation of one or sometimes two sulfate esters, adenosine 5'-phosphosulfate (APS) and 3'-phosphoadenosine-5'-phosphosulfate3'-Phosphoadenosine-5'-phosphosulfate
3'-Phosphoadenosine-5'-phosphosulfate is a derivative of adenosine monophosphate that is phosphorylated at the 3' position and has a sulfate group attached to the 5' phosphate. This anion, abbreviated PAPS, serves as a coenzyme in sulfotransferase reactions...
(PAPS). Sulfate is an inert anion, so nature activates it by the formation of these ester derivatives, which are susceptible to reduction to sulfite. Many organisms utilize these reactions for metabolic purposes or for the biosynthesis
Biosynthesis
Biosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...
of sulfur compounds required for life.
Safety
Because they are widely used in commercial products, the safety aspects of organosulfates are heavily investigated.Human Health
Alkyl sulfates if ingested are well absorbed and are metabolized into a C3, C4 or C5 sulfate and an additional metabolite. The highest irritant of the alkyl sulfates is sodium laurylsulfate with the threshold before irritation at a concentration of 20%. Surfactants in consumer products are typically mixed reducing likelihood of irritation. According to OECD TG 406, alkyl sulfates in animal studies were not found to be skin sensitizers.Laboratory studies have not found alkyl sulfates to be genotoxic, mutagenic
Mutagen
In genetics, a mutagen is a physical or chemical agent that changes the genetic material, usually DNA, of an organism and thus increases the frequency of mutations above the natural background level. As many mutations cause cancer, mutagens are therefore also likely to be carcinogens...
or carcinogenic
Carcinogen
A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...
. No long term reproductive effects have been found.
Environment
The primary disposal of alkyl sulfate from used commercial products is wastewater. The concentration of alkylsulfates in effluent from waste water treatment plants (WWTP) has been measured at 10ug/l and lower. Alkyl sulfates biodegrade easily, even starting likely before reaching the WWTP. Once at the plant, they are rapidly removed by biodegradationBiodegradation
Biodegradation or biotic degradation or biotic decomposition is the chemical dissolution of materials by bacteria or other biological means...
. Invertebrates were found to be the most sensitive trophic group to alkyl sulfates. Sodium laurylsulfate tested on Uronema parduczi, a protozoan, was found to have the lowest effect value with the 20 h-EC5 being 0.75 mg/l. Chronic exposure tests with C12 to C18 with the invertebrate Ceriodaphnia dubia found the highest toxicity is with C14 (NOEC was 0.045mg/l).
In terms of thermal stability, alkyl sulfates degrade well before reaching their boiling point due to low vapor pressure (for C8-18 from 10-11 to 10-15 hPa). Soil sorption is proportional to carbon chain length, with a length of 14 and more having the highest sorption rate. Soil concentrations have been found to vary from 0.0035 to 0.21 mg/kg dw.