Methoxymethylfurfural (MMF or 5-methoxymethylfuran-2-carbaldehyde) is an
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...
derived from dehydration of
sugars
Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double s ...
and subsequent etherification with
methanol
Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...
.
[van Putten, R-J., van der Waal J.C. de Jong, E., Rasrendra C.B., Heeres, E.J. and de Vries HG. (2011) Furan-based platform chemicals of the future. Dehydration of hexoses as biosustainable product route. Chemical Reviews submitted.] This colorless liquid is soluble in a wide range of solvents including lower alcohols. The molecule is a derivative of
furan
Furan is a heterocyclic organic compound, consisting of a five-membered aromatic ring with four carbon atoms and one oxygen atom. Chemical compounds containing such rings are also referred to as furans.
Furan is a colorless, flammable, highly ...
, containing both
aldehyde
In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...
and
ether
In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be c ...
(methoxymethyl) functional groups. MMF has been detected in the leaves and roots of Chilean ''Jaborosa magellanica'' (Solanaceae).
It has a typical odor suggestive of maraschino cherries.
[Hind, J.D. and Crayton, F.H. (1963) Tobacco flavorants. US 3,095,882] MMF can be made from a wide range of
carbohydrate
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ma ...
containing feedstocks including
sugar
Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double ...
,
starch
Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...
and
cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...
using a chemical catalytic process and is a potential "
carbon-neutral
Carbon neutrality is a state of net-zero carbon dioxide emissions. This can be achieved by balancing emissions of carbon dioxide with its removal (often through carbon offsetting) or by eliminating emissions from society (the transition to the "p ...
" feedstock for fuels and chemicals.
Production
Related to the production of furfural, MMF can be produced from C-6 sugars
hexoses
In chemistry, a hexose is a monosaccharide (simple sugar) with six carbon atoms. The chemical formula for all hexoses is C6H12O6, and their molecular weight is 180.156 g/mol.
Hexoses exist in two forms, open-chain or cyclic, that easily conver ...
such as
glucose
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...
and
fructose
Fructose, or fruit sugar, is a Ketose, ketonic monosaccharide, simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galacto ...
. It is formed via the dehydration of the hexoses and subsequent etherification of
hydroxymethylfurfural
Hydroxymethylfurfural (HMF), also 5-(hydroxymethyl)furfural, is an organic compound formed by the dehydration of reducing sugars. It is a white low-melting solid (although commercial samples are often yellow) which is highly soluble in both water ...
(HMF).
[ Already in 1936 a batch process was patented for the production of MMF and methyl levulinate.][Sprengler, O., Weidenhagen, R. and Korotkyj, B. DE632322 Verfahren zur Herstellung von Alkoxymethylfurfurolen und Lävulinsäurealkylestern] Bicker reported first order kinetics for the dehydration of fructose, etherification of HMF into MMF and by-products formation in methanol. An MMF yield of 78% at 99% conversion was obtained at 240 °C and a residence time of 2 s. At short residence times, especially at lower temperatures significant amounts of HMF were observed and smaller amount of MMF. The amount of MMF increased with residence time at the cost of the amount of HMF, which indicates that MMF formation goes through HMF. Reactions in various alcohols by Brown et al. led to the formation of the appropriate HMF ether and levulinic acid ester. A number of primary and secondary alcohols was tested, from methanol to 2-butanol. In methanol a yield of 43% MMF was reported in combination with 47% methyl levulinate. Garves has shown that also cellulose is efficiently degraded by alcohols and strong acid-catalysts at 180 °C to 200 °C within minutes. In methanol methylglucosides, MMF and methyl levulinates plus methyl formates
Formate (IUPAC name: methanoate) is the conjugate base of formic acid. Formate is an anion () or its derivatives such as ester of formic acid. The salts and esters are generally colorless.Werner Reutemann and Heinz Kieczka "Formic Acid" in ''U ...
are formed in consecutive reactions, accompanied by some humic residues.
Uses
The synthesis of novel biomass-based vinyl polymers from 5-methoxymethyl furfural as the starting material was described by Yoshida. HMF and MMF are also key molecules into the conversion of liquid biofuels
Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels, such as oil. According to the United States Energy Information Administration (E ...
. HMF and MMF can be converted to a wide range of mono- and dialkoxymethyl ethers. The compounds can also further converted to 2,5-dimethylfuran (DMF) and valeric biofuels. Oxidation of MMF results in the formation of 2,5-furandicarboxylic acid, which has been proposed as a replacement of terephthalic acid
Terephthalic acid is an organic compound with formula C6H4(CO2H)2. This white solid is a commodity chemical, used principally as a precursor to the polyester PET, used to make clothing and plastic bottles. Several million tonnes are produced annua ...
for the production of a wide range of plastics including polyesters
Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include natural ...
and polyamides
A polyamide is a polymer with repeating units linked by amide bonds.
Polyamides occur both naturally and artificially. Examples of naturally occurring polyamides are proteins, such as wool and silk. Artificially made polyamides can be made throug ...
. The potential applications of furan based building blocks for polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
applications has been extensively reviewed by Gandini. Patents have appeared that MMF prevents the growth of fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
in leathers, paints, foods and fabrics[Constantin, J.M., Humphreys, T.W. Lange, H.B. Shew, D. and Wagner, J.R. (1963) US. Patent 3,080,279, Mar. 5, 1963.] and that MMF as a part of a much broader spectrum of active compounds is effective against cardio, cerebro-vascular and Alzheimer's diseases and depression. The addition of MMF and other alkoxymethyl furfurals to a tobacco product has been patented because it acts as a fragrance
An aroma compound, also known as an odorant, aroma, fragrance or flavoring, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficiently vol ...
to provide a sweet flavor in the smoke.[
]
As an ingredient in food
Unlike HMF, MMF has not been found to a major extent in natural product
A natural product is a natural compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life. Natural products can also be prepared by chemical syn ...
s and in food
Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...
items. However, Podesta has shown that MMF is a constituent of the leaves and roots of Chilean ''Jaborosa magellanica'' (Griseb.) Dusen (Solanaceae). MMF occurs at concentrations of 5 mg MMF per kg dried roots and leaves. It was also present as a component of the roots of ''Asparagus cochinchinesis'' and ''Asparagus lucidus'', however it was assumed that the ''A. lucidus'' product had been formed as an artifact from fructose during the isolation process.[ On the contrary EMF, the ethanol ether of HMF can be found in many alcoholic beverages such as beer and wine, especially those who still contain high sugar levels at the end of the fermentation.][
]
Toxicity
It has been claimed that 5-methoxymethyl-2-furaldehyde prevents the growth of fungi in leathers, paints, foods and fabrics.[ However, the first phase of REACH testing has shown that the oral LD50 value of MMF in Wistar rats was established to exceed 2000 mg/kg body weight. According to the Regulation (EC) No 1272/2008 on classification, labelling and packaging of substances and mixtures, MMF does not have to be classified and has no obligatory labelling requirement for oral toxicity. It was found that MMF gave positive results in the skin irritation test and should be classified as a skin sensitizer.
]
Quantification
MMF can be quantified by using both GC and HPLC
High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to pa ...
. MMF can routinely been analyzed on a GC using for example a Varian VF-WAXms column with a temperature profile up to 250˚C and FID detector. When analyzed by HPLC it can be quantified by UV. In the picture below the UV spectrum is shown. The peak maximum in methanol is at 279.5 nm (Molar extinction coefficient
In chemistry, the molar absorption coefficient or molar attenuation coefficient is a measurement of how strongly a chemical species absorbs, and thereby attenuates, light at a given wavelength. It is an intrinsic property of the species. The SI u ...
ε 13854 M−1.cm−1).
The IR sample below was recorded on a Nicolet 6700 FT-IR
Fourier-transform infrared spectroscopy (FTIR) is a technique used to obtain an infrared spectrum of absorption or emission of a solid, liquid, or gas. An FTIR spectrometer simultaneously collects high-resolution spectral data over a wide spectra ...
at room temperature using the liquid film (diamond ATR-cell) procedure.
:
History
The first publication on MMF dates from 1927, by Haworth et al., in which it was observed as a product of tetramethylfructose dehydration in an attempt to deduce the structure of sucrose. Already in 1936 a German patent was published on the production of MMF from fructose.[ It was later also synthesised by Wolfrom et al. from tetramethyl glucoseen. Both substrates showed an efficient conversion into MMF under aqueous acidic conditions.][ Wolfrom, M. L., Wallace, E. G., Metcalf, E. A. (1942) J. Am. Chem. Soc. 64, 265-269.] The first claims for industrial applications arose in the sixties.[
]
References
{{Reflist
Aldehydes
Furfurals