Amine oxide

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General structure of an amine oxide Amine Oxides General Formulae.png
General structure of an amine oxide

In chemistry, an amine oxide, also known as an amine N-oxide or simply N-oxide, is a chemical compound that has the chemical formula R3N+−O−. It contains a nitrogen-oxygen coordinate covalent bond with three additional hydrogen and/or substituent-groups attached to nitrogen. Sometimes it is written as R3N→O or, alternatively, [1] as R3N=O.

Contents

In the strict sense, the term amine oxide applies only to oxides of tertiary amines. Sometimes it is also used for the analogous derivatives of primary and secondary amines.

Examples of amine oxides include pyridine-N-oxide, a water-soluble crystalline solid with melting point 62–67 °C, and N-methylmorpholine N-oxide, which is an oxidant.

Applications

Amine oxides are surfactants commonly used in consumer products such as shampoos, conditioners, detergents, and hard surface cleaners. [2] Alkyl dimethyl amine oxide (chain lengths C10–C16) is the most commercially used amine oxide. [3] They are considered a high production volume class of compounds in more than one member country of the Organisation for Economic Co-operation and Development (OECD); with annual production over 26,000, 16,000 and 6,800 tonnes (28,700, 17,600 and 7,500 short tons) in the US, Europe, and Japan, respectively. [2] In North America, more than 95% of amine oxides are used in home cleaning products. [4] They serve as stabilizers, thickeners, emollients, emulsifiers, and conditioners with active concentrations in the range of 0.1–10%. [2] The remainder (< 5%) is used in personal care, institutional, commercial products [5] and for unique patented uses such as photography. [2]

Lauryldimethylamine oxide, a fatty amine derivative, is a germicidal ingredient in many cosmetics. Lauryldimethylamine oxide.png
Lauryldimethylamine oxide, a fatty amine derivative, is a germicidal ingredient in many cosmetics.

Properties

Amine oxides are used as protecting group for amines and as chemical intermediates. Long-chain alkyl amine oxides are used as amphoteric surfactants and foam stabilizers.

Amine oxides are highly polar molecules and have a polarity close to that of quaternary ammonium salts. Small amine oxides are very hydrophilic and have an excellent water solubility and a very poor solubility in most organic solvents.

Amine oxides are weak bases with a pKb of around 4.5 that form R3N+−OH, cationic hydroxylamines, upon protonation at a pH below their pKb.

Synthesis

Almost all amine oxides are prepared by the oxidation of either tertiary aliphatic amines or aromatic N-heterocycles. Hydrogen peroxide is the most common reagent both industrially and in academia, however peracids are also important. [6] More specialised oxidising agents can see niche use, for instance Caro's acid or mCPBA. Spontaneous or catalysed reactions using molecular oxygen are rare. Certain other reactions will also produce amine oxides, such as the retro-Cope elimination, however they are rarely employed.

Reactions

Amine oxides exhibit many kinds of reactions. [7]

in a 1,2-rearrangement:
Meisenheimer 1 2.svg
or a 2,3-rearrangement:
Meisenheimer 2 3.svg
Polonovski Reaktion.svg

Metabolites

Amine oxides are common metabolites of medication and psychoactive drugs. Examples include nicotine, Zolmitriptan, and morphine.

Amine oxides of anti-cancer drugs have been developed as prodrugs that are metabolized in the oxygen-deficient cancer tissue to the active drug.

Human safety

Amine oxides (AO) are not known to be carcinogens, dermal sensitizers, or reproductive toxicants. They are readily metabolized and excreted if ingested. Chronic ingestion by rabbits found lower body weight, diarrhea, and lenticular opacities at a lowest observed adverse effect levels (LOAEL) in the range of 87–150 mg AO/kw bw/day. Tests of human skin exposure have found that after 8 hours less than 1% is absorbed into the body. Eye irritation due to amine oxides and other surfactants is moderate and temporary with no lasting effects. [2]

Environmental safety

Amine oxides with an average chain length of 12.6 have been measured to be water-soluble at ~410 g/L. They are considered to have low bioaccumulation potential in aquatic species based on log Kow data from chain lengths less than C14 (bioconcentration factor < 87%). [2] Levels of AO in untreated influent were found to be 2.3–27.8 ug/L, while in effluent they were found to be 0.4–2.91 ug/L. The highest effluent concentrations were found in oxidation ditch and trickling filter treatment plants. On average, over 96% removal has been found with secondary activated sludge treatment. [3] Acute toxicity in fish, as indicated by 96h LC50 tests, is in the range of 1,000–3,000 ug/L for carbon chain lengths less than C14. LC50 values for chain lengths greater than C14 range from 600 to 1400 ug/L. Chronic toxicity data for fish is 420 ug/L. When normalized to C12.9, the NOEC is 310 ug/L for growth and hatchability. [3]

See also

Related Research Articles

In chemistry, amines are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally 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, trimethylamine, and aniline. Inorganic derivatives of ammonia are also called amines, such as monochloramine.

<span class="mw-page-title-main">Amide</span> Organic compounds of the form RC(=O)NR′R″

In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula R−C(=O)−NR′R″, where R, R', and R″ represent any group, typically organyl groups or hydrogen atoms. The amide group is called a peptide bond when it is part of the main chain of a protein, and an isopeptide bond when it occurs in a side chain, as in asparagine and glutamine. It can be viewed as a derivative of a carboxylic acid with the hydroxyl group replaced by an amine group ; or, equivalently, an acyl (alkanoyl) group joined to an amine group.

<span class="mw-page-title-main">Carboxylic acid</span> Organic compound containing a –C(=O)OH group

In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group attached to an R-group. The general formula of a carboxylic acid is often written as R−COOH or R−CO2H, sometimes as R−C(O)OH with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion.

<span class="mw-page-title-main">Ester</span> Compound derived from an acid

In chemistry, an ester is a compound derived from an acid in which the hydrogen atom (H) of at least one acidic hydroxyl group of that acid is replaced by an organyl group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well, but not according to the IUPAC.

<span class="mw-page-title-main">Ketone</span> Organic compounds of the form >C=O

In organic chemistry, a ketone is an organic compound with the structure R−C(=O)−R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group −C(=O)−. The simplest ketone is acetone, with the formula (CH3)2CO. Many ketones are of great importance in biology and in industry. Examples include many sugars (ketoses), many steroids, and the solvent acetone.

<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">Beckmann rearrangement</span> Chemical rearrangement

The Beckmann rearrangement, named after the German chemist Ernst Otto Beckmann (1853–1923), is a rearrangement of an oxime functional group to substituted amides. The rearrangement has also been successfully performed on haloimines and nitrones. Cyclic oximes and haloimines yield lactams.

<span class="mw-page-title-main">Oxime</span> Organic compounds of the form >C=N–OH

In organic chemistry, an oxime is an organic compound belonging to the imines, with the general formula RR’C=N−OH, where R is an organic side-chain and R' may be hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. O-substituted oximes form a closely related family of compounds. Amidoximes are oximes of amides with general structure R1C(=NOH)NR2R3.

<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.

<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.

The Pummerer rearrangement is an organic reaction whereby an alkyl sulfoxide rearranges to an α-acyloxy–thioether (monothioacetal-ester) in the presence of acetic anhydride.

<span class="mw-page-title-main">Palladium(II) acetate</span> Chemical compound

Palladium(II) acetate is a chemical compound of palladium described by the formula [Pd(O2CCH3)2]n, abbreviated [Pd(OAc)2]n. It is more reactive than the analogous platinum compound. Depending on the value of n, the compound is soluble in many organic solvents and is commonly used as a catalyst for organic reactions.

Pyrylium is a cation with formula C5H5O+, consisting of a six-membered ring of five carbon atoms, each with one hydrogen atom, and one positively charged oxygen atom. The bonds in the ring are conjugated as in benzene, giving it an aromatic character. In particular, because of the positive charge, the oxygen atom is trivalent. Pyrilium is a mono-cyclic and heterocyclic compound, one of the oxonium ions.

<span class="mw-page-title-main">Lead(IV) acetate</span> Organometallic compound (Pb(C2H3O2)4)

Lead(IV) acetate or lead tetraacetate is an metalorganic compound with chemical formula Pb(C2H3O2)4. It is a colorless solid that is soluble in nonpolar, organic solvents, indicating that it is not a salt. It is degraded by moisture and is typically stored with additional acetic acid. The compound is used in organic synthesis.

The Stieglitz rearrangement is a rearrangement reaction in organic chemistry which is named after the American chemist Julius Stieglitz (1867–1937) and was first investigated by him and Paul Nicholas Leech in 1913. It describes the 1,2-rearrangement of trityl amine derivatives to triaryl imines. It is comparable to a Beckmann rearrangement which also involves a substitution at a nitrogen atom through a carbon to nitrogen shift. As an example, triaryl hydroxylamines can undergo a Stieglitz rearrangement by dehydration and the shift of a phenyl group after activation with phosphorus pentachloride to yield the respective triaryl imine, a Schiff base.

<span class="mw-page-title-main">Lauryldimethylamine oxide</span> Chemical compound

Lauryldimethylamine oxide (LDAO), also known as dodecyldimethylamine oxide (DDAO), is an amine oxide–based nonionic surfactant, with a C12 (dodecyl) alkyl tail. It is one of the most frequently-used surfactants of this type. Like other amine oxide–based surfactants it is antimicrobial, being effective against common bacteria such as S. aureus and E. coli, however, it is also non-denaturing and may be used to solubilize proteins.

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

An oxaziridine is an organic molecule that features a three-membered heterocycle containing oxygen, nitrogen, and carbon. In their largest application, oxaziridines are intermediates in the industrial production of hydrazine. Oxaziridine derivatives are also used as specialized reagents in organic chemistry for a variety of oxidations, including alpha hydroxylation of enolates, epoxidation and aziridination of olefins, and other heteroatom transfer reactions. Oxaziridines also serve as precursors to amides and participate in [3+2] cycloadditions with various heterocumulenes to form substituted five-membered heterocycles. Chiral oxaziridine derivatives effect asymmetric oxygen transfer to prochiral enolates as well as other substrates. Some oxaziridines also have the property of a high barrier to inversion of the nitrogen, allowing for the possibility of chirality at the nitrogen center.

In organic chemistry, the Ganem oxidation is a name reaction that allows for the preparation of carbonyls from primary or secondary alkyl halides with the use of trialkylamine N-oxides, such as N-methylmorpholine N-oxide or trimethylamine N-oxide.

Hydroxylamine-<i>O</i>-sulfonic acid Chemical compound

Hydroxylamine-O-sulfonic acid (HOSA) or aminosulfuric acid is the inorganic compound with molecular formula H3NO4S that is formed by the sulfonation of hydroxylamine with oleum. It is a white, water-soluble and hygroscopic, solid, commonly represented by the condensed structural formula H2NOSO3H, though it actually exists as a zwitterion and thus is more accurately represented as +H3NOSO3−. It is used as a reagent for the introduction of amine groups (–NH2), for the conversion of aldehydes into nitriles and alicyclic ketones into lactams (cyclic amides), and for the synthesis of variety of nitrogen-containing heterocycles.

References

  1. ↑ Durrant, Marcus C. (2015). "A quantitative definition of hypervalency". Chemical Science. 6 (11): 6614–6623. doi:10.1039/C5SC02076J. PMC   6054109 . PMID   30090275.
  2. 1 2 3 4 5 6 Organisation for Economic Co-operation and Development (OECD) (2006). "Amine Oxides". OECD Existing Chemicals Database. Archived from the original on 22 February 2014.
  3. 1 2 3 Sanderson, H; C Tibazarwa; W Greggs; DJ Versteeg (2009). "High Production Volume Chemical Amine Oxides [C8–C20]". Risk Analysis. 29 (6): 857–867. doi:10.1111/j.1539-6924.2009.01208.x. PMID   19504658. S2CID   45774397.
  4. ↑ Modler, RF; Inoguchi Y (2004). "CEH Marketing Research Report: Surfactants, Household Detergents, and their Raw Materials". Chemical Economics Handbook. Menlo Park, CA: SRI Consulting.
  5. ↑ Sanderson, H; Counts JL; Stanton K; Sedlak R (2006). "Exposure and Prioritization—Human Screening Data and Methods for High Production Volume Chemicals in Consumer Products: Amine Oxides a Case Study". Risk Analysis. 26 (6): 1637–1657. doi: 10.1111/j.1539-6924.2006.00829.x . PMID   17184403.
  6. ↑ Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.), New York: Wiley-Interscience, p. 1779, ISBN   978-0-471-72091-1
  7. ↑ Albini, Angelo (1993). "Synthetic utility of amine N-oxides". Synthesis. 1993 (3): 263–77. doi:10.1055/s-1993-25843.
  8. ↑ Waldmann, T.; et al. (2012). "Oxidation of an Organic Adlayer: A Bird's Eye View". Journal of the American Chemical Society . 134 (21): 8817–22. doi:10.1021/ja302593v. PMID   22571820.
  9. ↑ J. Meisenheimer, Ber. 52. 1667 (1919)
  10. ↑ Smith, Michael B.; March, Jerry (2001). March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (5th ed.). Wiley-Interscience. ISBN   0-471-58589-0.[ page needed ]
  11. ↑ Grierson, D (1990). "The Polonovski Reaction". Org. React. 39: 85. doi:10.1002/0471264180.or039.02. ISBN   0471264180.
  12. ↑ Polonovski, Max; Polonovski, Michel (1927). ""Sur les aminoxydes des alcaloïdes. III. Action des anhydrides et chlorures d'acides organiques. Préparation des bases nor."". Bull. Soc. Chim. Fr. 41: 1190–1208.
  13. ↑ Kürti, Laszlo; Czako, Barbara (2005). Strategic Applications of Named Reactions in Organic Synthesis (paperback ed.). Elsevier Science. ISBN   0-12-429785-4.[ page needed ]
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