4940-11-8

Basic information

• Product Name: Ethyl maltol
• Synonyms: 2-ethyl-3-hydroxy-4h-pyran-4-on;2-ethylpyromeconicacid;4H-Pyran-4-one,2-ethyl-3-hydroxy-;veltolplus;ETHYL MALTOL;FEMA 3487;2-ETHYL-3-HYDROXY-4H-PYRAN-4-ONE;2-ETHYL-3-HYDROXY-4-PYRONE
• CAS NO: 4940-11-8
• Molecular Formula: C₇H₈O₃
• Molecular Weight: 140.14
• EINECS: 225-582-5
• Product Categories: Food and Feed Additive;Food & Feed ADDITIVES;Food & Flavor Additives;Building Blocks;Chemical Synthesis;Heterocyclic Building Blocks;Pyrans;Food Additives
• Mol File: 4940-11-8.mol

Chemical Properties

• Melting Point: 85-95 °C(lit.)
• Boiling Point: 196.62°C (rough estimate)
• Flash Point: 124.8 °C
• Appearance: White crystalline powder
• Density: 1.1624 (rough estimate)
• Vapor Pressure: 0.2Pa at 24℃
• Refractive Index: 1.4850 (estimate)
• Storage Temp.: 2-8°C
• Solubility: Chloroform (Slightly), Methanol (Slightly)
• PKA: 8.38±0.10(Predicted)
• Water Solubility: 9.345g/L at 24℃
• Merck: 14,3824
• CAS DataBase Reference: Ethyl maltol(CAS DataBase Reference)
• NIST Chemistry Reference: Ethyl maltol(4940-11-8)
• EPA Substance Registry System: Ethyl maltol(4940-11-8)

Safety Data

• Hazard Codes: Xn
• Statements: 22
• Safety Statements: 36
• WGK Germany: 3
• RTECS: UQ0840000
• Hazardous Substances Data: 4940-11-8(Hazardous Substances Data)

Usage

Uses

Used in Pharmaceutical Industry:
Ethyl maltol is used as an anticonvulsant, acting as a depressant on motor activity.
Used in Flavor and Fragrance Industry:
Ethyl maltol is used as a flavoring agent for its unique odor and sweet taste that resembles fruit. It is particularly effective as a flavor and fragrance enhancer in foods, especially baked goods, beverages, and synthetic berry and citrus flavorings.
Used in Tobacco Products:
Ethyl maltol is used to minimize undesirable flavors in tobacco products, improving their overall taste and aroma.
Used in Cough Syrup and Vitamins:
Ethyl maltol is used to enhance the taste of cough syrup and vitamins, making them more palatable for consumption.
Used in Cosmetics:
Ethyl maltol is used in the cosmetics industry to add a pleasant odor and improve the sensory experience of the products.
Used in Saccharin-Containing Products:
Ethyl maltol is used to enhance the taste of products containing saccharin, a low-calorie sweetener, by adding a sweet, fruity flavor.
Taste threshold values:
At 70 ppm, ethyl maltol has sweet, burnt cotton, sugar candy-like taste with jamy, strawberry notes.
Occurrence:
Ethyl maltol has apparently not been reported to occur in nature and is obtained by chemical synthesis.
Chemical Properties:
Ethyl maltol forms white crystals (melting point 90-91°C) with a very sweet, caramel-like odor. It has a sweet, fruit-like flavor and odor in dilute solution. Several syntheses have been developed for its preparation, including a one-pot process where β-ethylfurfuryl alcohol is treated with halogen to give 4-halo-6-hydroxy-2-ethyl-2H-pyran-3(6H)-one, which can be converted to ethylmaltol by aqueous hydrolysis.

History

In 1891, Bernhardi first discovered synthesis, and its derivatives are used for therapeutic purposes and can be prepared in industrial experiments. As war ammunition, it was first used by France in fortress warfare, and was prepared before the war. In October 1914, the French used it as a gas grenade, planned for the fortress battle. On January 7, 1915, it was actually used in the forest of Argonnen on the western front of France.

Preparation

Several syntheses have been developed for its preparation. In a one-pot process, for example, ??-ethylfurfuryl alcohol is treated with halogen to give 4-halo- 6-hydroxy-2-ethyl-2H-pyran-3(6H)-one, which need not be isolated and can be converted to ethylmaltol by aqueous hydrolysis.

Preparation

Fermentation method. Kojic acid is obtained from starch fermentation, and then ethyl maltol is obtained by etherification, oxidation, debenzylation, decarboxylation, hydroxylation and reduction. Pyrofuroic acid method. A solution of pyrofuroic acid and acetic acid at a temperature of 90°C was added dropwise to the ether solution of diacetyl peroxide within 1~2h, and then the mixture was raised to 2h within 2h. 110 ° C, so that the 2-position of pyrofuroic acid can be directly alkylated to obtain ethyl maltol. furfuryl alcohol method. Furfuryl alcohol is chlorinated in methanol aqueous solution by introducing chlorine gas to generate 4-chloro-3-hydroxy-4H-ketone, and then heated and hydrolyzed to obtain pyrofuroic acid; under alkaline conditions, pyrofuroic acid is condensed with acetaldehyde to obtain hydroxyethyl Pyrofuroic acid, which is reduced to ethyl maltol with zinc powder in hydrochloric acid. Furfural method. Furfural reacts with ethylmagnesium bromide to obtain ethylfurfuryl alcohol (α-furan alkanol), which is then oxidized by chlorine gas in methanol aqueous solution at 0°C, and then heated to 100°C for hydrolysis to obtain ethyl maltol.

Production Methods

Unlike maltol, ethyl maltol does not occur naturally. It may be prepared by treating a-ethylfurfuryl alcohol with a halogen to produce 4-halo-6-hydroxy-2-ethyl-2H-pyran-3(6H)-one, which is converted to ethyl maltol by hydrolysis.

Flammability and Explosibility

Notclassified

Pharmaceutical Applications

Ethyl maltol is used in pharmaceutical formulations and food products as a flavoring agent or flavor enhancer in applications similar to maltol. It has a flavor and odor 4–6 times as intense asmaltol. Ethyl maltol is used in oral syrups at concentrations of about 0.004% w/v and also at low levels in perfumery.

Safety Profile

Moderately toxic by ingestion and subcutaneous routes. Mutation data reported. When heated to decomposition it emits acrid smoke and irritating fumes.

Safety

In animal feeding studies, ethyl maltol has been shown to be well tolerated with no adverse toxic, reproductive, or embryogenic effects. It has been reported that while the acute toxicity of ethyl maltol, in animal studies, is slightly greater than maltol, with repeated dosing the opposite is true. The WHO has set an acceptable daily intake for ethyl maltol at up to 2 mg/kg bodyweight. LD50 (chicken, oral): 1.27 g/kg LD50 (rat, oral): 1.15 g/kg LD50 (mouse, oral): 0.78 g/kg LD50 (mouse, SC): 0.91 g/kg

Synthesis

From kojic acid

Metabolism

When orally administered, ethyl maltol was rapidly and extensively absorbed. Elimination was also extensive and rapid, involving conjugation as the glucuronide and ethereal sulphate, and excretion in the urine to the extent of 65-70% within 24 hr. Rate studies after iv dosage indicated that the bulk (86%) of the recovered conjugates was excreted within 6 hr (Rennhard, 1971).

storage

Solutions may be stored in glass or plastic containers. The bulk material should be stored in a well-closed container, protected from light, in a cool, dry place.

Regulatory Status

GRAS listed. Included in the FDA Inactive Ingredients Database (oral syrup).

InChI:InChI=1/C7H8O3/c1-2-6-7(9)5(8)3-4-10-6/h3-4,9H,2H2,1H3

Synthetic route

ethylfurfuryl alcohol (4208-61-1, 119619-55-5, 127418-31-9, 128948-40-3) → 2-ethyl-3-hydroxy-4-pyranone (4940-11-8)

Conditions	Yield
With chlorine In methanol; water 1.) -5 deg C; 2.) 90-95 deg C, 3.5 h;	67%
With chlorine In methanol; water at 90 - 95℃; for 3.5h; Rearrangement;	67%
Stage #1: ethylfurfuryl alcohol With oxygen In methanol at 93℃; Molecular sieve; Stage #2: With oxygen In methanol at 20℃; for 2h; Stage #3: With hydrogenchloride In water at 100℃; for 2h; pH=2.5 - 3; Solvent; Temperature;	66.8%
With tert-butylhypochlorite In acetic acid	65%

hydroxyethyl maltol → 2-ethyl-3-hydroxy-4-pyranone (4940-11-8)

Conditions	Yield
With hydrogenchloride; zinc In ethanol at 55℃; for 3h; Temperature;

3-hydroxy-2-ethyl-4H-thiopyran-4-thione → 2-ethyl-3-hydroxy-4-pyranone (4940-11-8)

Conditions	Yield
With Lawessons reagent In 1,4-dioxane for 1h; Heating;

furfural (98-01-1) → 2-ethyl-3-hydroxy-4-pyranone (4940-11-8)

Conditions	Yield
Multi-step reaction with 4 steps 1: hydrogen / water / 8 h / 90 °C / 15001.5 Torr 2: chlorine / water; methanol / -5 - 60 °C 3: sodium hydroxide / 3 h / 55 °C 4: zinc; hydrogenchloride / ethanol / 3 h / 55 °C View Scheme

(2-furyl)methyl alcohol (98-00-0) → 2-ethyl-3-hydroxy-4-pyranone (4940-11-8)

Conditions	Yield
Multi-step reaction with 3 steps 1: chlorine / water; methanol / -5 - 60 °C 2: sodium hydroxide / 3 h / 55 °C 3: zinc; hydrogenchloride / ethanol / 3 h / 55 °C View Scheme

2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + benzyl bromide (100-39-0) → 3-(benzyloxy)-2-ethyl-4H-pyran-4-one (111782-87-7)

Conditions	Yield
In acetone for 6h; Reflux;	98%
Stage #1: 2-ethyl-3-hydroxy-4-pyranone With sodium hydroxide In methanol Heating; Stage #2: benzyl bromide In methanol for 6h; Heating; Further stages.;	85%
With sodium hydroxide In ethanol Heating;	80%

2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + benzenesulfonic acid (98-11-3) → 3,4-dihydroxy-2-ethylpyrylium benzenesulfonate

Conditions	Yield
In methanol for 1h; Reflux;	98%

2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + salicylic acid (69-72-7) → 2-ethyl-3-hydroxy-4-pyrone/salicylic acid 1:1 cocrystals (1325228-63-4)

Conditions	Yield
In methanol at 64℃; for 1h;	98%

2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + methyl iodide (74-88-4) → 2-ethyl-3-methoxy-4Hpyran-4-one (50741-69-0)

Conditions	Yield
With potassium carbonate In acetone for 4h; Inert atmosphere; Reflux;	97%
With potassium carbonate In acetone at 25℃; for 4h;	93%
With potassium carbonate In acetone for 8h; Reflux;

dichloro(pentamethylcyclopentadienyl)rhodium (III) dimer + 2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + sodium methylate (124-41-4) → Rh(C5(CH3)5)Cl(C5H2O3C2H5) (173413-66-6)

Conditions	Yield
In methanol byproducts: NaCl; N2-atmosphere; stoich. amts., refluxing for 3 h; solvent removal, extn. into CH2Cl2, filtration (Celite), evapn., recrystn. (CH2Cl2/light petroleum);	96%

2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + titanium tetrachloride (7550-45-0) → bis-ethylmaltoldichloro-titanium(IV)

Conditions	Yield
In tetrahydrofuran ethylmaltol stirred with anhyd. THF at room temp., TiCl4 added dropwise to soln., stirred at room. temp for 30 min; filtered, washed with Et2O, recrystd. from CH2Cl2-petroleum ether (1:1);	95%

2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + {(η6-1,3,5-Me3C6H3)RuCl2}2 + sodium methylate (124-41-4) → (C6(CH3)3H3)RuCl(OOC5H2C2H5O) (151781-33-8)

Conditions	Yield
In methanol; water byproducts: NaCl; Sodium methoxide and ethylmaltol are added to a suspn. of the Ru-compd. in CH3OH/H2O and the mixt. is refluxed for 2 h.; The solvent is removed. The residue is dissolved in CH2Cl2. After filtn. the solvent is evaporated, recrystn. from CH2Cl2/diethylether, elem. anal.;	80%

zinc(II) sulfate heptahydrate + 2-ethyl-3-hydroxy-4-pyranone (4940-11-8) → C14H14O6Zn (98445-51-3)

Conditions	Yield
Stage #1: 2-ethyl-3-hydroxy-4-pyranone With lithium hydroxide monohydrate In water at 20℃; for 0.5h; Stage #2: zinc(II) sulfate heptahydrate In water at 20℃; for 5h;	77%

vanadyl sulfate trihydrate + 2-ethyl-3-hydroxy-4-pyranone (4940-11-8) → bis(ethylmaltolato)(ethylmaltol)oxovanadium(IV) monohydrate

Conditions	Yield
In water VOSO4*3H2O and ethylmaltol (molar ratio 1:2) suspended in water at 45°C; pptd. over 15-20 min; cooled to room temp.; filtered; ppt. air dried; elem. anal.;	72%

oxovanadium(IV) sulfate + 2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + salicylaldehyde (90-02-8) + anthranilic acid hydrazide (1904-58-1) → C21H18N3O6V

Conditions	Yield
Stage #1: salicylaldehyde; anthranilic acid hydrazide In methanol for 0.5h; Stage #2: oxovanadium(IV) sulfate; 2-ethyl-3-hydroxy-4-pyranone In methanol for 0.5h;	72%

2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + 4-tert-Butylaniline (769-92-6) → 1-(4-(tert-butyl)phenyl)-2-ethyl-3-hydroxypyridin-4(1H)-one

Conditions	Yield
With hydrogenchloride In ethanol; water at 160℃; for 12h; pH=5; Autoclave;	70%

lanthanum(III) nitrate hexahydrate + 2-ethyl-3-hydroxy-4-pyranone (4940-11-8) → La(ethylmaltol(1-))3 (960499-98-3)

Conditions	Yield
With triethylamine In ethanol Ln(NO3)*6H2O was added to soln. ligand in EtOH and heated until ligand completely dissolved, Et3N was added and stirred for 18-24 h; ppt. was filtered, washed with cold water and cold MeOH and dried in vacuo; elem. anal.;	68%

bis(acetylacetonate)oxovanadium (3153-26-2) + 2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + 2-chloro-N′-(3-ethoxy-2-hydroxybenzylidene)benzohydrazide → C23H20ClN2O7V

Conditions	Yield
Stage #1: bis(acetylacetonate)oxovanadium; 2-ethyl-3-hydroxy-4-pyranone; 2-chloro-N′-(3-ethoxy-2-hydroxybenzylidene)benzohydrazide In methanol at 20℃; for 0.5h; Stage #2: With air In methanol	68%

2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + tin(II) n-butoxide (14254-05-8, 26306-46-7, 130287-64-8) → Sn(ethylmaltol)2 (361148-46-1)

Conditions	Yield
In toluene a soln. of hydroxyketone in toluene was added a stirred soln. of Sn-compound in toluene under N2, the soln. was stirred for 2 h then left at room temp.; elem. anal.;	66%

2-ethyl-3-hydroxy-4-pyranone (4940-11-8) → 2-ethyl-3-hydroxy-5-bromo-4H-pyran-4-one (95790-62-8)

Conditions	Yield
With N-Bromosuccinimide; 2,2'-azobis(isobutyronitrile) In tetrachloromethane at 95℃; for 18h; Inert atmosphere;	66%
With N-Bromosuccinimide; 2,2'-azobis(isobutyronitrile) In tetrachloromethane at 95℃; Inert atmosphere; Schlenk technique;	32%
With N-Bromosuccinimide; 2,2'-azobis(isobutyronitrile) In tetrachloromethane at 95℃; for 18h; Inert atmosphere; Schlenk technique;

oxovanadium(IV) sulfate + 2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + 2-hydroxy-3-bromobenzaldehyde (1829-34-1) + 3-hydroxybenzoic hydrazide (5818-06-4) → C21H16BrN2O7V

Conditions	Yield
Stage #1: 2-hydroxy-3-bromobenzaldehyde; 3-hydroxybenzoic hydrazide In methanol for 0.5h; Stage #2: oxovanadium(IV) sulfate; 2-ethyl-3-hydroxy-4-pyranone In methanol for 0.5h;	65%

2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + europium(III) nitrate hexahydrate → Eu(ethylmaltol(1-))3*2.5H2O

Conditions	Yield
With triethylamine In ethanol Ln(NO3)*6H2O was added to soln. ligand in EtOH and heated until ligand completely dissolved, Et3N was added and stirred for 18-24 h; ppt. was filtered, washed with cold water and cold MeOH and dried in vacuo; elem. anal.;	64%

2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + benzyl chloride (100-44-7) + ethanolamine (141-43-5) → 3-Benzyloxy-1,2-diethyl-1H-pyridin-4-one

Conditions	Yield
Stage #1: 2-ethyl-3-hydroxy-4-pyranone; benzyl chloride With sodium hydroxide In methanol; ethanol; water Stage #2: ethanolamine With sodium hydroxide In methanol; ethanol; water	63%
Stage #1: 2-ethyl-3-hydroxy-4-pyranone; benzyl chloride With sodium hydroxide In methanol; water Stage #2: ethanolamine With sodium hydroxide In ethanol; water	63%

bis(acetylacetonate)oxovanadium (3153-26-2) + 2-ethyl-3-hydroxy-4-pyranone (4940-11-8) + N′-(3-ethoxy-2-hydroxybenzylidene)pivalohydrazide → C21H25N2O7V

Conditions	Yield
In methanol at 20℃; for 0.5h;	62%

Upstream product

• 4208-61-1 ethylfurfuryl alcohol 
• 98-01-1 furfural 
• 98-00-0 (2-furyl)methyl alcohol 

Downstream Products

• 111782-87-7 3-(benzyloxy)-2-ethyl-4H-pyran-4-one 
• 696584-98-2 3-hydroxy-2-ethyl-1-hexylpyridin-4(1H)-one 
• 115900-75-9 1,2-diethyl-3-hydroxypyridin-4-one 
• 115864-73-8 2-ethyl-3-hydroxy-1-methylpyrid-4-one 
• 178547-52-9 1-phenyl-2-ethyl-3-hydroxy-4-pyridinone 
• 115864-74-9 CP95 
• 189131-43-9 1-(4'-methylbenzyl)-3-hydroxy-2-ethyl-4-pyridinone 
• 204717-51-1 1-(4'-tolyl)-3-hydroxy-2-ethyl-4-pyridinone 
• 762225-06-9 1-(4'-trifluoromethylbenzyl)-3-hydroxy-2-ethyl-4-pyridinone 
• 219757-45-6 1-(4'-fluorobenzyl)-3-hydroxy-2-ethyl-4-pyridinone 
• 123742-56-3 3-benzyloxy-2-ethyl-1-methyl-4(1H)-pyridinone 
• 143697-02-3 2-ethyl-3-(benzyloxy)-4-hydroxypyridine 
• 349141-17-9 2-ethyl-3,4-dibenzyloxypyridine 
• 349141-18-0 2-ethyl-3,4-dibenzyloxypyridine N-oxide 

Relevant articles and documents

Method for preparing ethyl maltol from corn cobs with furfuryl alcohol process

The invention discloses a method for preparing ethyl maltol from corn cobs with a furfuryl alcohol process in the technical field of chemical synthesis. The method comprises the steps as follows: preparing furfural from the corn cobs with a two-step method; generating of furfuryl alcohol from furfural through a reaction: furfural and a platinum-loaded nitrogen-doped graphene material are placed in a reaction device, distilled water is added, hydrogen is introduced, and the mixture reacts at 90-160 DEG C for 4-8 h and furfuryl alcohol is prepared; preparing pyromeconic acid from furfuryl alcohol through chlorination and isomerization reactions; preparing hydroxyethyl maltol through condensation; finally, preparing ethyl maltol through reduction: heating is performed continuously after reaction for distilling off an ethanol aqueous solution, the temperature is increased for distilling off crude ethyl maltol, chloroform is added to the crude ethyl maltol for dissolving the crude ethyl maltol, the solution is cooled to 0 DEG C for recrystallization, crystals are dried, and finished maltol is obtained. Pollution-free, green, environment-friendly and pure food-grade ethyl maltol which is high in yield and produces no wastewater basically is prepared with the preparation method; as the structure of the maltol is similar to that of the ethyl maltol, the preparation method can be general, and all that is required is to adjust other raw materials in the reactions.

Maltol and homolog preparation method by means of molecular oxygen oxidation

The invention provides a maltol and homolog preparation method by means of molecular oxygen oxidation. The method comprises the following steps of charging, a first-stage oxidation reaction, a second-stage oxidation reaction and hydrolysis. According to the first-stage oxidation reaction, alpha-furyl alcohol is used as a raw material, gas with an oxygen content of 15%-85% is used as an oxidizing agent, a heteroatom molecular sieve and basic resin are used as a composite catalyst in a solvent, and an oxidizing ring opening rearrangement reaction is conducted at the temperature of 50-160 DEG C; according to the second-stage oxidation reaction, the temperature drops to 10-40 DEG C, gas with an oxygen content of 90% or above is pumped in, an epoxidation reaction is conducted, and the temperature of the reaction is kept for 0.5-3 h. According to the method, the production yield reaches 50% or above, and the production yield reaches 67% or above in the condition of optimization; the oxidation reaction conducted by using molecular oxygen has the advantages of energy conservation, low cost and environmental protection, and recycling and application of the catalysts are easier to achieve by means of the composite catalyst made from the heteroatom molecular sieve and the basic resin.

A novel heterocyclic atom exchange reaction with Lawesson's reagent: A one-pot synthesis of dithiomaltol

A one-pot reaction of maltol with Lawesson's reagent generates dithiomaltol, a thiopyran-4-thione, via an unusual heterocyclic atom exchange (HCAE) reaction; only pyrones with proton or aliphatic substituents undergo the HCAE substitution. The Royal Society of Chemistry 2006.

Method of synthesizing gamma pyrones

Maltol and ethyl maltol can be produced from a haloenone intermediate by reacting the intermediate with acid in a reaction medium comprising an aprotic solvent.

Process for the production of isosolanone and solanone, intermediates useful in said process and organoleptic uses of said intermediates

Described is a novel genus of compounds defined according to the structure: STR1 wherein Z represents hydrogen, MgX and the moiety having the structure: STR2 and X represents chlor, bromo, or iodo; as well as 5-isopropyl-8-methyl-5,8-nonadien-2-one; uses of same as intermediates in a process for producing isosolanone and solanone; and organoleptic uses of 5-isopropyl-8-methyl-5,8-nonadien-2-one and 2,6-dimethyl-5-methylene-1-hepten-4-ol. The novel process of our invention involved the steps of: (i) formation of the compound having the structure: STR3 by means of reacting 3-methyl-2-methylenebutanal with the compound having the structure: STR4 (ii) acid hydrolysis of the resulting compound in order to form 2,6-dimethyl-5-methylene-1-heptene-4-ol; (iii) reaction of 2,6-dimethyl-5-methylene-1-hepten-4-ol with methyl aceto acetate in order to form 2,6-dimethyl-5-methylene-1-hepten-4-yl aceto acetate or, directly, 5-isopropyl-8-methyl-5,8-nonadiene-2-one; (iv) reacting 2,6-dimethyl-5-methylene-1-hepten-4-yl aceto acetate in the presence of an appropriate catalyst to form the 5-isopropyl-8-methyl-5,8-nonadiene-2-one; and (v) isomerizing the 5-isopropyl-8-methyl-5,8-nonadien-2-one in order to form a mixture of solanone and the isosolanone or 5-isopropyl-8-methyl-5,8-nonadiene-2-one.

Conversion of Secondary Furfuryl Alcohols and Isomaltol to Maltol and Related γ-Pyrones

A one-pot synthesis of maltol and ethylmaltol is reported.Treatment of methylfurfuryl alcohol with 2 equiv of halogen affords good yields of 4-halo-6-hydroxy-2-methyl-2H-pyran-3(6H)-ones (8), which need not be isolated and can be converted to maltol by aqueous hydrolysis in the same vessel.A similar sequence employing ethylfurfuryl alcohol yields ethylmaltol.By a related series of reactions, isomaltol (9) can be converted to maltol.

Process for preparing 3-oxy-4H-pyran-4-one derivatives

A process for preparing a 3-oxy-4H-pyran-4-one derivative which comprises the steps of: 1. epoxidizing a 3-oxo-3,6-dihydro-2H-pyran derivative with a peroxide to obtain a 4,5-epoxy-3-oxotetrahydropyran derivative, and 2. heating the 4,5-epoxy-3-oxotetrahydropyran derivative.