Dimethyl dicarbonate

E number E242INS 242CAS 4525-33-1

Listed as a preservative by Canada, Codex and the US.

Listed as preservatives (CA, US, Codex)
Chemical structure of Dimethyl dicarbonate, from PubChem compound 3086
Structure from PubChem CID 3086 (National Library of Medicine, public domain). A depiction of one compound: where a listing covers a family, or a substance has no single structure, this page shows none.

Dimethyl dicarbonate is a cold sterilant for beverages, added just before bottling to kill yeasts and moulds without heating the drink. It breaks down to methanol and carbon dioxide within hours.

Where it is and isn’t permitted

Status of Dimethyl dicarbonate by jurisdiction. Every jurisdiction this site covers is listed, including those where the substance does not appear.
JurisdictionStatusScope and limitsCitation
Australia and New ZealandFood Standards Australia New ZealandNo listed food uses foundThis site has not matched this substance to any food use on this jurisdiction’s list of authorised food additives. A food additive may be used only in foods that list names. Flavourings, enzymes, processing aids and added nutrients are regulated separately and do not appear on it.
CanadaHealth CanadaPermitted, with conditions

highest permitted level 250 mg/kg

3 permitted uses

Show every permitted use
  • In: Cider; Fruit wine; Perry; Unstandardized alcoholic ciders. Purpose: Preservative. Limit: 250 ppm. Amendment notices: NOM/ADM-0009. — Health Canada, List of Permitted Preservatives (List 11), item D.1(a)
  • In: Unstandardized water-based non-alcoholic beverages. Purpose: Preservative. Limit: 250 ppm. Amendment notices: NOM/ADM-0170. — Health Canada, List of Permitted Preservatives (List 11), item D.1(b)
  • In: Wine. Purpose: Preservative. Limit: 200 ppm. Amendment notices: NOM/ADM-0009. — Health Canada, List of Permitted Preservatives (List 11), item D.1(c)
Health Canada, List of Permitted Preservatives (List 11)and 2 further provisionsretrieved 2026-10-17
European UnionEuropean Commission / EFSAPermitted, with conditions

9 food categories

highest permitted level 250 mg/l

Show every food category
  • 14.1.4 Flavoured_drinks — 250 mg/lML = 250 mg/l.
  • 14.1.5.2 other — 250 mg/lML = 250 mg/l. only liquid tea concentrate. Note 24: Ingoing amount, residues not detectable.
  • 14.2.2 Wine and other products defined in Annex VII part II of Regulation (EU) No 1308/2013 — 250 mg/lML = 250 mg/l. only alcohol-free. Note 24: Ingoing amount, residues not detectable.
  • 14.2.3 Cider and perry — 250 mg/lML = 250 mg/l. Note 24: Ingoing amount, residues not detectable.
  • 14.2.4 Fruit wine and made wine — 250 mg/lML = 250 mg/l. only fruit wine, alcohol reduced fruit wine and wino owocowe jakościowe, wino owocowe likierowe, wino owocowe aromatyzowane, wino z soku winogronowego, aromatyzowane wino z soku winogronowego, wino owocowe niskoalkoholowe and aromatyzowane wino owocowe niskoalkoholowe. Note 24: Ingoing amount, residues not detectable.
  • 14.2.7.1 Aromatised wines — 250 mg/lML = 250 mg/l. Note 24: Ingoing amount, residues not detectable.
  • 14.2.7.2 Aromatised wine-based drinks — 250 mg/lML = 250 mg/l. Note 24: Ingoing amount, residues not detectable.
  • 14.2.7.3 Aromatised wine-product cocktails — 250 mg/lML = 250 mg/l. Note 24: Ingoing amount, residues not detectable.
  • 14.2.8 Other alcoholic beverages including mixtures of alcoholic beverages with non-alcoholic beverages and other alcoholic beverages based on distilled alcohol with alcoholic strength by volume less than 15 % — 250 mg/lML = 250 mg/l. Note 24: Ingoing amount, residues not detectable.
Regulation (EC) No 1333/2008and 8 further provisionsretrieved 2026-10-18
Great BritainFood Standards Agency / Food Standards ScotlandPermitted, with conditions

9 food categories

highest permitted level 250 mg/kg or mg/l

Show every food category
  • 14.1.4 Flavoured drinks — 250 mg/kg or mg/lML = 250. Note (24): Ingoing amount, residues not detectable.
  • 14.1.5.2 Other — 250 mg/kg or mg/lML = 250. only liquid tea concentrate. Note (24): Ingoing amount, residues not detectable.
  • 14.2.2 Wine and other products defined by Regulation (EEC) No 1234/2007, and alcohol-free counterparts — 250 mg/kg or mg/lML = 250. only alcohol-free. Note (24): Ingoing amount, residues not detectable.
  • 14.2.3 Cider and perry — 250 mg/kg or mg/lML = 250. Note (24): Ingoing amount, residues not detectable.
  • 14.2.4 Fruit wine and made wine — 250 mg/kg or mg/lML = 250. Only fruit wine, alcohol reduced wine and wino owocowe markowe , wino owocowe wzmocnione , wino owocowe aromatyzowane , wino z soku winogronowego and aromatyzowane wino z soku winogronowego. Note (24): Ingoing amount, residues not detectable.
  • 14.2.7.1 Aromatised wines — 250 mg/kg or mg/lML = 250. Note (24): Ingoing amount, residues not detectable.
  • 14.2.7.2 Aromatised wine-based drinks — 250 mg/kg or mg/lML = 250. Note (24): Ingoing amount, residues not detectable.
  • 14.2.7.3 Aromatised wine-product cocktails — 250 mg/kg or mg/lML = 250. Note (24): Ingoing amount, residues not detectable.
  • 14.2.8 Other alcoholic drinks including mixtures of alcoholic drinks with non-alcoholic drinks and spirits with less than 15 % of alcohol — 250 mg/kg or mg/lML = 250. Period of application: From 28 December 2012. Note (24): Ingoing amount, residues not detectable.
Assimilated Regulation (EC) No 1333/2008and 8 further provisionsretrieved 2026-10-18
JapanConsumer Affairs AgencyPermitted, with conditions
Designated additive: Appended Table 1, item 296, 二炭酸ジメチル (“Dimethyl Dicarbonate” in the unofficial English translation). …

Designated additive: Appended Table 1, item 296, 二炭酸ジメチル (“Dimethyl Dicarbonate” in the unofficial English translation). Standards for use — Specifications and Standards for Foods, Food Additives, etc. (MHW Notification No. 370 of 1959), Part II (Food Additives), F (Standards for use), entry 二炭酸ジメチル: (1) [may be used only in the foods stated] “二炭酸ジメチルは果実酒及び清涼飲料水(ミネラルウォーター類を除く。以下この目において同じ。)以外の食品に使用してはならない。” (2) [sets maximum levels of use for the foods stated] “二炭酸ジメチルの使用量は、果実酒(ぶどう酒を除く。)及び清涼飲料水にあってはその1kgにつき0.25g以下、ぶどう酒にあってはその1kgにつき0.20g以下でなければならない。” The Japanese is the standard as published. There is no official English translation of the Notification; the English in square brackets is this site’s description of what each sentence does, not a translation of the foods or the levels. Compositional specifications for this additive, in the same Notification, are not imported and are not shown here; nor are the general rules in F 添加物一般, which apply to every additive.

Regulations for Enforcement of the Food Sanitation Act (MHW Ordinance No. 23 of 1948), Appended Table 1retrieved 2026-10-18
South KoreaMinistry of Food and Drug SafetyNo listing matchedThis site imports Part III of South Korea’s Standards and Specifications for Food Additives, matched by CAS number, then INS number, then exact name. Mixed preparations and sanitisers are not imported, and an entry whose identifiers disagreed with a page’s is held for review, so an empty row does not show that South Korea does not permit the substance.
United StatesFood and Drug AdministrationPermitted, with conditions21 CFR 172.133retrieved 2026-10-17
Codex AlimentariusCodex Alimentarius Commission / JECFAPermitted, with conditions

8 food categories

highest permitted level 250 mg/kg

Show every food category and its notes
  • 14.1.2 Fruit and vegetable juices — 250 mg/kg
    • Note XS247 Excluding products conforming to the General Standard for Fruit Juices and Nectars (CXS 247-2005).
    • Note XS356R Excluding products conforming to the Regional Standard for Fermented Noni Fruit Juice (CXS 356R-2023).
  • 14.1.3 Fruit and vegetable nectars — 250 mg/kg
    • Note XS247 Excluding products conforming to the General Standard for Fruit Juices and Nectars (CXS 247-2005).
  • 14.1.4 Water-based flavoured drinks, including "sport," “energy,” or "electrolyte" drinks and particulated drinks — 250 mg/kg
    • Note 18 As added level; residue not detected in ready-to-eat food.
  • 14.1.5 Coffee, coffee substitutes, tea, herbal infusions, and other hot cereal and grain beverages, excluding cocoa — 250 mg/kg
    • Note 18 As added level; residue not detected in ready-to-eat food.
  • 14.2.2 Cider and perry — 250 mg/kg
    • Note 18 As added level; residue not detected in ready-to-eat food.
  • 14.2.3 Grape wines — 200 mg/kg
    • Note 18 As added level; residue not detected in ready-to-eat food.
  • 14.2.4 Wines (other than grape) — 250 mg/kg
    • Note 18 As added level; residue not detected in ready-to-eat food.
  • 14.2.5 Mead — 200 mg/kg
    • Note 18 As added level; residue not detected in ready-to-eat food.
CXS 192-1995 Table One, INS 242and 7 further provisionsretrieved 2026-09-07

How much is permitted

A listing usually limits the quantity as well as the food. Only one of the forms that takes is a figure: quantum satis and good manufacturing practice permit the amount the technological effect requires and no more, which is a limit rather than the absence of one. Figures below are the range across every food category this page is listed in, and categories differ between regulators — see how much is permitted.

Canada200 mg/kg – 250 mg/kg3 numeric limit
European Union250 mg/kg9 numeric limit
Great Britain250 mg/kg9 numeric limit
Japan—1 no quantity stated
United States—1 no quantity stated
Codex Alimentarius200 mg/kg – 250 mg/kg8 numeric limit

What it is made from

A synthetic compound made from methanol and phosgene chemistry. It is designed to disappear: it is not present in the drink by the time it is opened.

  • Vegan
  • Vegetarian

Compare other additives on the dietary indexes.

CAS registry number
4525-33-1
InChIKey
GZDFHIJNHHMENY-UHFFFAOYSA-N
PubChem
CID 3086

The two specifications, compared

The European Union sets identity and purity by regulation; JECFA publishes its own through FAO, advisory until a country adopts it. Both documents are below in full. These are the parameters each puts a number on.

ParameterEuropean UnionJECFA
Assayno less than 99.8 %no less than 99.8 %
Leadno more than 2 mg/kgno more than 2 mg/kg
Arsenicno more than 3 mg/kg—
Mercuryno more than 1 mg/kg—

The two documents state the same figures for every parameter compared here.

How the EU defines it

The legal specification an additive must meet to be sold as this E number in the EU — what it is, how it may be made, and the purity it must reach. From Commission Regulation (EU) No 231/2012.

E 242 Dimethyl dicarbonate

Synonyms: DMDC; Dimethyl pyrocarbonate

Assay, identification and purity criteria

Description and assay

Einecs
224-859-8
Chemical name
Dimethyl dicarbonate; Pyrocarbonic acid dimethyl ester
Chemical formula
C₄H₆O₅
Molecular weight
134,09
Assay
Content not less than 99,8 %
Description
Colourless liquid, decomposes in aqueous solution. It is corrosive to skin and eyes and toxic by inhalation and ingestion

Identification

Decomposition
After dilution positive tests for CO₂ and methanol
Melting point
17 °C
Boiling point
172 °C with decomposition
Density 20 °C
Approximately 1,25 g/cm³
Infrared absorption spectrum
Maxima at 1 156 and 1 832 cm⁻¹

Purity criteria

Dimethyl carbonate
Not more than 0,2 %
Chlorine, total
Not more than 3 mg/kg
Arsenic
Not more than 3 mg/kg
Lead
Not more than 2 mg/kg
Mercury
Not more than 1 mg/kg

Commission Regulation (EU) No 231/2012, Annex, E 242

How JECFA defines it

The international specification for identity and purity, prepared by the Joint FAO/WHO Expert Committee on Food Additives and published by FAO. It is a different document from any above, written by a different body and revised on its own cycle; it is advisory, and a country adopts it or does not.

INS 242 Dimethyl Dicarbonate

Synonyms: DMDC, dimethyl pyrocarbonate; INS No. 242 Dimethyl pyrocarbonate; DMDC

Assay, identification and purity criteria

Description and assay

Specification history
Prepared at the 37th JECFA (1990), published in FNP 52 (1990). Metals and arsenic specifications revised at the 63rd JECFA (2004). Considered to be acceptable in accordance with GMP (max 250mg/l) at the 37th JECFA (1990)
Chemical names
Dimethyl dicarbonate
C.A.S. number
004-525-33-1
Chemical formula
C 4 H 6 O 5
Formula weight
139.09
Assay
Not less than 99.8%
DESCRIPTION
Colourless liquid. Caution: Corrosive to eyes and skin and toxic by inhalation and ingestion; must be kept in a tightly sealed container to exclude moisture.
FUNCTIONAL USES
Preservative
METHOD OF ASSAY
Introduce about 70 ml of pure acetone into a 150-ml glass beaker. Using a disposable 2 ml syringe weigh 1.0-1.3 g of the sample to an accuracy of ±0.1 mg into the glass beaker. Pipette exactly 20 ml dibutyl amine solution (add chlorobenzene to 120 g dibutyl amine until the 1 L mark is reached) while stirring. Titrate the solution potentiometrically with 1N hydrochloric acid. Run a blank test. Calculate the % of dimethyldicarbonate from: where V 1 = amount of hydrochloric acid used for titration of the sample (ml) V 2 = amount of hydrochloric acid used for titration of the blank (ml) t = normality of hydrochloric acid W = weight of sample (g)

Identification

Solubility (Vol. 4)
Soluble in water with decomposition; miscible with toluene
Infrared absorption
The infrared spectrum of the sample corresponds with the reference infrared spectrum below

Purity criteria

Dimethyl carbonate
Not more than 0.2% See description under TESTS
Lead (Vol. 4)
Not more than 2 mg/kg Determine using an atomic absorption technique appropriate to the specified level. The selection of sample size and method of sample preparation may be based on the principles of the method described in Volume 4, “Instrumental Methods.”
Test: Dimethyl carbonate
Apparatus Gas chromatograph with a flame ionization detector, equipped for capillary gas chromatography, and inlet part for the "on column" technique (e.g., Carlo Erba Fraktovap 4160, or Hewlett-Packard 5880 or 5792). - Capillary: 50 m SE 30-D (internal diameter: 0,3 mm). - Potentiometric recorder, 1 mV. - Microliter syringes with quartz needles, contents 0,010 ml, suitable for the "on column" technique (e.g., microliter syringe from SGE, type 5 A- SOC), (See Remark 5 below). Rolled rim glass vial, 10 ml content. - Seal cap for the rolled rim vial with teflon coating. - Closure tongs for the rolled rim vial - Auxiliary for the peak area determination (e.g. HP calculator 3353). Reagents Methylisobutylketone, purest grade. Operating conditions Temperatures: - Injection block: Room temperature (approximately 25 o ) - Detector: 200 o - Capillary Tube: Initial temperature 30 o ; Preliminary phase 5 min, Rate of ascent 40 o /min; Final temperature 120 o , Final phase 5 min Carrier gas: - Preliminary pressure: 3.0 bar (Helium) - Capillary tubes: Approx. 11 ml/min - Make-up gas: 28 ml/min Hydrogen: 35 ml/min Air: 300 ml/min Recorder feed: 1 cm/min Procedure Accurately weigh about 10 g of the sample to the nearest mg (W 1 mg) into a rolled rim vial. Add in a quantity of dimethyl-isobutylketone (W 2 mg), corresponding to the anticipated dimethylcarbonate content. Seal the rolled rim vial, mix well and inject 0.002 ml. Retention times: - Dimethylcarbonate: Approx. 2 min - Methylisobutylketone: Approx. 4.5 min - Dimethyldicarbonate: Approx. 8 min Typical Chromatogram: See Figure below. Determine the peak areas of the standard (F2) and dimethylcarbonate (F1). Calculation Calculate the % of dimethyl carbonate from: where K = is a Correction Factor for Dimethylcarbonate (See Remark 3, below) Remarks 1. It should be noted the DMDC is sensitive to moisture and heat. 2. If so-called peak splits occur to some extent at the given gaschromatography conditions, then the peak areas are best determined by summation of the areas under both peaks. 3. The correction factor for dimethylcarbonate should be determined with corresponding test solutions in DMDC which is to the greatest extent possible free of dimethylcarbonate. 4. The specimen mixed with the standard must be measured immediately. 5. Hamilton syringes with Metal needles can result in a partial decomposition of the DMDC.
Test: Infrared spectrum
Dimethyl dicarbonate
Test: Typical chromatogram
Dimethyl dicarbonate

FAO JECFA Monograph 1 (2006)

Every name it appears under

52 recorded names. A label may use any of them.

E number

  • E242

INS number

  • 242

CAS registry number

  • 4525-33-1

As it appears in regulation

  • Dimethyl dicarbonate

Other names

  • Baycovin; DEPA;Dekapex; Diethyl dicarbonate;Ue 5908
  • Dicarbonic acid, 1,3-dimethyl ester
  • Dicarbonic acid, C,C'-dimethyl ester
  • Dicarbonic acid, dimethyl ester
  • Dimethyl dicarbonate
  • Dimethyl dicarbonate, for histidine methylation
  • Dimethyl oxydiformate
  • Dimethyl pyrocarbonate
  • Dimethyl pyrocarbonate; Methyl pyrocarbonate; Pyrocarbonic acid dimethyl ester; Velcorin
  • Dimethyldicarbonate
  • dimethylpyrocarbonate
  • DMDC
  • E 242
  • Formic acid, oxydi-, dimethyl ester
  • Formic acid, oxydi-, dimethyl ester (7CI,8CI)
  • HSDB 8117
  • INS NO.242
  • INS-242
  • methoxycarbonyl methyl carbonate
  • methoxycarbonyl methyl carbonate;DMPC Dimethyl pyrocarbonate Pyrocarbonic acid dimethyl ester;
  • Methyl pyrocarbonate
  • Pyrocarbonic acid dimethyl ester
  • Velcorin

Systematic names

  • methoxycarbonyl methyl carbonate

The EU re-evaluation programme

Every additive authorised in the EU before 20 January 2009 was put back through EFSA by Commission Regulation (EU) No 257/2010, and this one is named in it. What the Regulation required is below; whether the opinion has since been published is not something this site records.

  • To be evaluated by 31 December 2015. Named in Annex II, Part II, point 1 as “Dimethyl dicarbonate”, among the additives given priority within its class.

Hazard reference values

Values set by assessing bodies. A body that has not set a value is not listed here.
TypeValuePopulationAssessed byOpinion
ADInot specified—JECFA1990

Evidence and how bodies read it

What assessing bodies concluded

Each conclusion is paraphrased in the body's own framing, from the published opinion linked beneath it. Where bodies differ, both stand; this site does not adjudicate between them or add a view of its own.

  1. EFSA 2015

    The ANS Panel concluded that an ADI could not be derived for dimethyl dicarbonate (E 242), which does not remain in treated beverages, and assessed its breakdown and reaction products instead. It found no indication of a safety concern at the currently reported uses and use levels, and said a new assessment would be warranted if conditions of use changed.

    Source document

Common questions

Assembled from what is above, in the words the questions are usually asked in. Each answer is the same statement the relevant section makes, with the same citations behind it.

What is E 242?
E 242 is Dimethyl dicarbonate. Dimethyl dicarbonate is a cold sterilant for beverages, added just before bottling to kill yeasts and moulds without heating the drink. It breaks down to methanol and carbon dioxide within hours.
What is Dimethyl dicarbonate used for in food?
It is listed as a preservative — the role Canada, Codex and the US assign it. This page shows every function each regulator records, with the citation for each.
Where is Dimethyl dicarbonate permitted?
Of the seven regulators this site reads, Canada, the EU, Great Britain, Japan, the US and the Codex standard permit it. Each permission is for named foods at named levels, not a blanket one; the table on this page gives them with citations.
Is Dimethyl dicarbonate vegan?
Yes. Dimethyl dicarbonate is not derived from animals, and is suitable for vegetarians. This page says what it is made from and how.

Sources for this page

  • ca retrieved 2026-10-17
  • eu retrieved 2026-10-18
  • gb retrieved 2026-10-18
  • jp retrieved 2026-10-18
  • ecfr retrieved 2026-10-17
  • gsfa retrieved 2026-09-07
  • euspecs retrieved 2026-10-18
  • jecfaspecs retrieved 2026-09-23

Full licence terms and publisher details on Sources. How this page is built and updated: Method.

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