Aqueous propylparaben solutions at pH 3–6 can be sterilized by
autoclaving, without decomposition.At pH 3–6, aqueous
solutions are stable (less than 10% decomposition) for up to about
4 years at room temperature, while solutions at pH 8 or above are
subject to rapid hydrolysis (10% or more after about 60 days at
propylparaben is one of the most frequently used preservatives against bacteria and mold. It has a low sensitizing and low toxicity factor, is reputed to be very safe, and considered to be a noncomedogenic raw material.
Produced by esterfying p-hydroxybenzoic acid with n-propanol, using an acid catalyst such as sulfuric acid and an excess
of propanol. The materials are heated in a glass-lined reactor under reflux. The acid is then neutralized with caustic soda and the
product is crystallized by cooling. The crystallized product is centrifuged, washed, dried under vacuum, milled and blended, all in
corrosion-resistant equipment to avoid metallic contamination.
Same with Method 1 in "Butyl p-hydroxybenzoate (07002)".
In calculation, per mL of 1 mol/L sodium hydroxide corresponds to 180.2mg of this goods (C10Hl2O8).
Adl? 0-10 mg/kg (FAO/WHO, 2001).
LD50? 3.7g/kg (mouse, oral).
GRAS? (FDA, § 184.1670, 2000).
HACSG? listed in the restricted list.
Aroma threshold values
Detection: 20 ppb
Colorless crystals or white powder or chunky white solid. Melting point 95-98°C. Odorless or faint aromatic odor. Low toxicity, Tasteless (numbs the tongue). pH: 6.5-7.0 (slightly acidic) in solution.
This substance is one of the parabens family. Parabens are esters formed by p-hydroxybenzoic acid
and an alcohol. They are largely used as biocides in
cosmetics and toiletries, medicaments, or food. They
have synergistic power with other biocides. Parabens
can induce allergic contact dermatitis, mainly in
chronic dermatitis and wounded skin.
2760--2002 GB (calculate in p-hydroxybenzoic acid; g/kg):
fresh fruit and vegetable 0.012; vinegar 0.10; carbonated beverages 0.20; fruit juice (fruit flavor) type beverages, jam (excluding canned), soy sauces 0.25; pastry stuffing 0.5 (the total amount of single use or mixed use with ethyl 4-hydroxybenzoate); egg yolk filling 0.20.
Another provision that sodium methylparaben is also equivalent application.
FAO/WHO (1984): Jam and jelly, 1000 mg/kg
FDA § 184.1670 (2000): 0.1%.
EEC(1990, mg/kg): Frozen drinks 160; beet pickled vegetables, salad dressings, 250; fragrance, fruit tarts, purees, concentrated soft drinks, 800; Fruit canned, salted fish, 1000.
Japan (calculate in p-hydroxybenzoic acid, g/kg; this product, g):
soy sauce 0.25g/L (this product 0.32); vinegarsoysoy 0.1g/L (This product 0.13); soft drinks and syrup 0.1 (this product 0.13); fruit sauce 0.2 (this product 0.26); fruits and vegetables 0.012 (this product 0.015).
Maximum stability of Propylparaben occurs at a pH of 4 to 5. Incompatible with alkalis and iron salts. Also incompatible with strong oxidizing agents and strong acids .
Propylparaben is a colorless and fine crystalline or white crystalline powder, almost odorless and with slightly astringent.Soluble in ethanol, ethyl ether, acetone and other organic solvents, slightly soluble in water.
Hazards & Safety Information
Category: Toxic substances
Toxicity classification :Moderate toxicity
Acute Toxicity :Celiac-mouse LD50: 200 mg/kg
Flammable hazardous characteristics :Flammable; excrete acrid and pungent smoke from fire
Storage and transport characteristics :Stored in the low-temperature, well-ventilated and dry warehouse
Fire extinguishing agent :water, carbon dioxide, dry powder, sand
Propylparaben occurs as a white, crystalline, odorless, and tasteless
Propylparaben is prepared by the esterification of p-hydroxybenzoic
acid with n-propanol.
Flash point data for Propylparaben are not available; however, Propylparaben is probably combustible.
The antimicrobial activity of propylparaben is reduced considerably
in the presence of nonionic surfactants as a result of micellization.
Absorption of propylparaben by plastics has been reported, with
the amount absorbed dependent upon the type of plastic and the
vehicle. Magnesium aluminum silicate, magnesium trisilicate,
yellow iron oxide, and ultramarine blue have also been reported to
absorb propylparaben, thereby reducing preservative efficacy.
Propylparaben is discolored in the presence of iron and is subject
to hydrolysis by weak alkalis and strong acids.
Propylparaben is widely used as an antimicrobial preservative in
cosmetics, food products, and pharmaceutical formulations.
It may be used alone, in combination with other paraben esters,
or with other antimicrobial agents. It is one of the most frequently
used preservatives in cosmetics.
The parabens are effective over a wide pH range and have a
broad spectrum of antimicrobial activity, although they are most
effective against yeasts and molds.
Owing to the poor solubility of the parabens, the paraben salts,
particularly the sodium salt, are frequently used in formulations.
This may cause the pH of poorly buffered formulations to become
Propylparaben (0.02% w/v) together with methylparaben
(0.18% w/v) has been used for the preservation of various
parenteral pharmaceutical formulations.
Air & Water Reactions
Water soluble [Hawley].
Propyl p-hydroxybenzoate is almost odorless.
ChEBI: The benzoate ester that is the propyl ester of 4-hydroxybenzoic acid. Preservative typically found in many water-based cosmetics, such as creams, lotions, shampoos and bath products. Also used as a food additive.
Propylparaben and methylparaben are affirmed GRAS direct food
substances in the USA at levels up to 0.1%. All esters except the
benzyl ester are allowed for injection in Japan.
In cosmetics, the EU and Brazil allow use of each paraben at
0.4%, but the total of all parabens may not exceed 0.8%. The upper
limit in Japan is 1.0%.
Accepted as a food additive in Europe. Included in the FDA
Inactive Ingredients Database (IM, IV, and SC injections; inhalations;
ophthalmic preparations; oral capsules, solutions, suspensions,
and tablets; otic, rectal, topical, and vaginal preparations).
Included in parenteral and nonparenteral medicines licensed in the
UK. Included in the Canadian List of Acceptable Non-medicinal
Propylparaben and other parabens are widely used as antimicrobial
preservatives in cosmetics, food products, and oral and topical
Propylparaben and methylparaben have been used as preservatives
in injections and ophthalmic preparations; however, they are
now generally regarded as being unsuitable for these types of
formulations owing to the irritant potential of the parabens.
Systemically, no adverse reactions to parabens have been
reported, although they have been associated with hypersensitivity
reactions. The WHO has set an estimated acceptable total daily
intake for methyl, ethyl, and propyl parabens at up to 10 mg/kg
LD50 (mouse, IP): 0.2 g/kg
LD50 (mouse, oral): 6.33 g/kg
LD50 (mouse, SC): 1.65 g/kg
White or almost white, crystalline powder.
1. Propylparaben Used as preservatives and antioxidants, and also used in the pharmaceutical industry
2. Used as the antimicrobial preservative in pharmaceuticals and cosmetics
3. According to ethyl p-hydroxybenzoate (17007)
4. Used as antiseptic and antimicrobial.
5. Used as the preservatives of food, cosmetics and medicines.
Pharmaceutic aid (antifungal). Antimicrobial preservative in foods and cosmetics.
This product can be derived from the esterification of p-hydroxybenzoic acid and n-propanol. First mix p-hydroxybenzoic acid with propanol and heat to dissolve. Then add sulfuric acid slowly and continue to heat for 8h of refluxion. After cooling, pour them into the 4% sodium carbonate solution for precipitation and crystallization. Filtrate and wash to neutral to obtain the crude product. After further ethanol recrystallization, the finished products are obtained. In the preparation, the cation exchange resin can be used in place of the sulfuric acid catalyst.
It can be derived from the esterification of p-hydroxybenzoic acid and n-propanol in the presence of sulfuric acid.
Add p-hydroxybenzoic acid and n-propanol in turn to the esterification reactor, and heat to dissolve. Add concentrated sulfuric acid slowly and heat for 8h of refluxion. Pour the reaction solution into 4% sodium carbonate solution before it is cooled. Constantly stir for precipitation and crystallization. Then the crude product can be obtained after centrifugal filtration and washed to neutral. Finally the finished product is acquired after activated carbon decolorization and ethanol recrystallization. The method of preparing ethyl p-hydroxybenzoate can also be used as a reference.
HOC6H4COOH + C3H7OH [H2SO4] → HOC6H4COOC3H7 + H2O