4-methyl-2-pentenoic acid

4-methyl-2-pentenoic acid is a branched unsaturated carboxylic acid with the molecular formula C₆H₁₀O₂. It is represented by the preferred chemical name (E,Z)-4-methylpent-2-enoic acid and related synonyms include 4-methyl pent-2-enoic acid and 3-iso propyl acrylic acid. The compound appears as a colorless liquid with a distinctive fatty and fruity odor profile often described in black tea and hops. This acid plays a role in contributing to complex flavor notes such as blueberry, guava, and strawberry. The compound is part of the class of alkenoic acids and is available commercially, mainly obtained via chemical synthesis. It is indexed in public chemical databases such as PubChem, supporting broad chemical characterization and regulatory information.

4-methyl-2-pentenoic acid naturally occurs in plants such as hops and black tea leaves, where it contributes to their distinctive aroma profiles. Its sensory profile described as fatty and fruity makes it valuable as a flavoring agent, particularly in recreating or enhancing notes of fruits like blueberry, guava, and strawberry in food products. This compound is registered under FEMA (US) as number 4180 and is approved as a flavoring ingredient under various food safety frameworks. Although it is not recommended for fragrance use, it is widely employed in flavor formulations across baked goods, beverages, dairy, and confectionery. The compound's inclusion follows guidelines established by the FEMA Expert Panel and European regulations such as REACH (EU) to ensure safe use in the food additive context.

The physical properties of 4-methyl-2-pentenoic acid influence its behavior in formulation and application. It has a boiling range near 203 to 204 °C at standard pressure and a melting point around 34 to 35 °C. The specific gravity measured at 25 °C ranges from 0.95 to 0.96, indicating a liquid density slightly less than water. The refractive index falls between 1.442 and 1.453 at 20 °C, which can assist in purity determination. The compound exhibits moderate vapor pressure of 0.052 mmHg at 25 °C, showing low volatility under ambient conditions. It is soluble in alcohol and slightly soluble in water with an estimated solubility of 8168 mg/L at 25 °C. The estimated logP of 1.68 indicates moderate lipophilicity, affecting its partitioning in mixtures. These properties bear on its incorporation into food flavor systems, influencing dispersion, intensity, and stability.

	(E)-4-methylpent-2-enoic acid
NIST Chemistry WebBook:	Search Inchi
Canada Domestic Sub. List:	10321-71-8
Pubchem (cid):	642039
Pubchem (sid):	135067900

(IUPAC):	Atomic Weights of the Elements 2011 (pdf)
Videos:	The Periodic Table of Videos
tgsc:	Atomic Weights use for this web site
(IUPAC):	Periodic Table of the Elements
FDA Substances Added to Food (formerly EAFUS):	View
HMDB (The Human Metabolome Database):	HMDB31561
FooDB:	FDB008176
Export Tariff Code:	2915.90.5050
VCF-Online:	VCF Volatile Compounds in Food
ChemSpider:	View

Safety information

Preferred SDS: View
European information :
Most important hazard(s):
C - Corrosive.
R 34 - Causes burns. S 02 - Keep out of the reach of children. S 24/25 - Avoid contact with skin and eyes. S 26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S 27 - Take off immediately all contaminated clothing. S 28 - After contact with skin, wash immediately with plenty of water. S 36/37/39 - Wear suitable clothing, gloves and eye/face protection.
Hazards identification
Classification of the substance or mixture
GHS Classification in accordance with 29 CFR 1910 (OSHA HCS)
None found.
GHS Label elements, including precautionary statements
Pictogram
Hazard statement(s)
None found.
Precautionary statement(s)
None found.
Oral/Parenteral Toxicity:
Not determined
Dermal Toxicity:
Not determined
Inhalation Toxicity:
Not determined

Safety in use information

Category:
flavoring agents
Recommendation for 4-methyl-2-pentenoic acid usage levels up to:
	not for fragrance use.
Maximised Survey-derived Daily Intakes (MSDI-EU):		0.012 (μg/capita/day)
Maximised Survey-derived Daily Intakes (MSDI-USA):		ND (μg/capita/day)
Modified Theoretical Added Maximum Daily Intake (mTAMDI):		2200 (μg/person/day)
Threshold of Concern:		1800 (μg/person/day)
Structure Class:		I
Use levels for FEMA GRAS flavoring substances on which the FEMA Expert Panel based its judgments that the substances are generally recognized as safe (GRAS).
The Expert Panel also publishes separate extensive reviews of scientific information on all FEMA GRAS flavoring substances and can be found at FEMA Flavor Ingredient Library
publication number: 22
Click here to view publication 22
		average usual ppm	average maximum ppm
baked goods:		10.00000	50.00000
beverages(nonalcoholic):		3.00000	15.00000
beverages(alcoholic):		-	-
breakfast cereal:		5.00000	25.00000
cheese:		3.00000	15.00000
chewing gum:		-	-
condiments / relishes:		5.00000	25.00000
confectionery froastings:		10.00000	50.00000
egg products:		-	-
fats / oils:		2.00000	10.00000
fish products:		2.00000	10.00000
frozen dairy:		3.00000	15.00000
fruit ices:		3.00000	15.00000
gelatins / puddings:		5.00000	25.00000
granulated sugar:		-	-
gravies:		15.00000	75.00000
hard candy:		-	-
imitation dairy:		3.00000	15.00000
instant coffee / tea:		-	-
jams / jellies:		5.00000	25.00000
meat products:		2.00000	10.00000
milk products:		3.00000	15.00000
nut products:		-	-
other grains:		5.00000	25.00000
poultry:		2.00000	10.00000
processed fruits:		2.00000	10.00000
processed vegetables:		-	-
reconstituted vegetables:		-	-
seasonings / flavors:		5.00000	25.00000
snack foods:		10.00000	50.00000
soft candy:		-	-
soups:		5.00000	25.00000
sugar substitutes:		-	-
sweet sauces:		5.00000	25.00000
Food categories according to Commission Regulation EC No. 1565/2000 (EC, 2000) in FGE.06 (EFSA, 2002a). According to the Industry the "normal" use is defined as the average of reported usages and "maximum use" is defined as the 95th percentile of reported usages (EFSA, 2002i).
Note: mg/kg = 0.001/1000 = 0.000001 = 1/1000000 = ppm.
		average usage mg/kg	maximum usage mg/kg
Dairy products, excluding products of category 02.0 (01.0):		3.00000	15.00000
Fats and oils, and fat emulsions (type water-in-oil) (02.0):		2.00000	10.00000
Edible ices, including sherbet and sorbet (03.0):		3.00000	15.00000
Processed fruit (04.1):		2.00000	10.00000
Processed vegetables (incl. mushrooms & fungi, roots & tubers, pulses and legumes), and nuts & seeds (04.2):		-	-
Confectionery (05.0):		10.00000	50.00000
Chewing gum (05.3):		-	-
Cereals and cereal products, incl. flours & starches from roots & tubers, pulses & legumes, excluding bakery (06.0):		5.00000	25.00000
Bakery wares (07.0):		10.00000	50.00000
Meat and meat products, including poultry and game (08.0):		2.00000	10.00000
Fish and fish products, including molluscs, crustaceans and echinoderms (MCE) (09.0):		2.00000	10.00000
Eggs and egg products (10.0):		-	-
Sweeteners, including honey (11.0):		-	-
Salts, spices, soups, sauces, salads, protein products, etc. (12.0):		5.00000	25.00000
Foodstuffs intended for particular nutritional uses (13.0):		10.00000	50.00000
Non-alcoholic ("soft") beverages, excl. dairy products (14.1):		-	-
Alcoholic beverages, incl. alcohol-free and low-alcoholic counterparts (14.2):		10.00000	50.00000
Ready-to-eat savouries (15.0):		15.00000	75.00000
Composite foods (e.g. casseroles, meat pies, mincemeat) - foods that could not be placed in categories 01.0 - 15.0 (16.0):		5.00000	25.00000

Safety references

European Food Safety Athority(EFSA):Flavor usage levels; Subacute, Subchronic, Chronic and Carcinogenicity Studies; Developmental / Reproductive Toxicity Studies; Genotoxicity Studies...

European Food Safety Authority (EFSA) reference(s):

Scientific Opinion on Flavouring Group Evaluation 95 (FGE.95): Consideration of aliphatic, linear or branched-chain saturated and unsaturated alcohols, aldehydes, acids and related esters evaluated by JECFA (69th meeting) structurally related to esters of branched- and straight-chain aliphatic saturated primary alcohols and of one secondary alcohol, and branched- and straight-chain unsaturated carboxylic acids evaluated by EFSA in FGE.05Rev1 (2008) View page or View pdf

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EPA Substance Registry Services (TSCA):10321-71-8

EPA ACToR:Toxicology Data

EPA Substance Registry Services (SRS):Registry

Laboratory Chemical Safety Summary :642039

National Institute of Allergy and Infectious Diseases:Data

WISER:UN 3265

WGK Germany:1

(E)-4-methylpent-2-enoic acid

Chemidplus:0010321718