99-76-3 Usage
Uses
Used in Cosmetic Industry:
Methylparaben is used as a preservative in beauty products such as cream cleansers, moisturizers, primers, and foundations. It provides anti-fungal and antibacterial properties, which help maintain the effectiveness and extend the shelf life of skincare, haircare, and cosmetic products.
Used in Pharmaceutical Industry:
Methylparaben is used as a preservative in pharmaceutical products, including ophthalmic solutions. It acts as an inhibitor of mold growth and to a lesser extent, bacterial growth, ensuring the safety and efficacy of these products.
Used in Food Industry:
Methylparaben is used as a preservative in foods and beverages. It is effective against yeast, molds, and bacteria, helping to maintain the quality and safety of these products over a wide pH range.
Used in Antimicrobial Applications:
Methylparaben is an antimicrobial agent that is active against yeast and molds. It is used in various applications where microbial control is necessary, such as in the production of cloudberry, yellow passion fruit juice, white wine, botrytised wine, and Bourbon vanilla.
General Description:
Methylparaben is a white free-flowing powder that is readily absorbed through the skin and gastrointestinal tract. Upon hydrolysis, it is hydrolyzed to p-hydroxybenzoic acid, and the conjugates formed get rapidly excreted in the urine.
Chemical Properties:
Methylparaben is a colorless crystalline powder that is odorless or has a faint characteristic odor and a slight burning taste. It is slightly soluble in water, easily soluble in ethanol, ether, acetone, and other organic solvents. Its effectiveness as a preservative increases with decreasing pH.
Aroma Threshold Values:
Detection: 2.6 ppm.
Content analysis
Method one: determinate according to the content analysis method in "butyl p-hydroxybenzoate (07002)". Per mL 1 mol/L sodium hydroxide is equivalent to the product (C8H8O3) 152.2mg.
Method two: Take 0.1 g (accurate to 1 mg) of the sample previously dried on silica gel for 5 h and move into a 300 ml flask with a glass plug. Plus l mol/L sodium hydroxide 10ml, heated in the water bath for 15min. After cooling, add 0.1mol/L potassium bromate 0.00ml, potassium bromide 5.0g and l mol/L hydrochloric acid 30ml. Put 15min in the dark room after sealing. Add potassium iodide 1 g, shake the flask vigorously, with 0.1mol/L sodium thiosulfate titration, with starch test solution (TS-235) as an indicator. Per ml 0.1mol/L potassium bromate is equivalent to the product (C8H8O3) 25.36mg.
Toxicity
ADI 0～10mg/kg(FAO/WHO,2001).
GRAS(FDA,§184．1490，2000).
LD503000mg/kg(Dog, mouth)
Utilization limitation
FAO/WHO (1984): Jam, jelly, 1000mg/kg (single or with benzoate, sorbic acid and potassium sorbate).
EEC(1990,mg/kg): For use in pigment solutions, flavor syrups, coffee extracts, frozen drinks, fruit, glucose and soft drinks, pickled fish, salad, sauce, snack food, concentrated soup and so on, limited to GMP; Beer 70; Snack cereals and soup concentrate 175, the same as "07018 p-hydroxybenzoate".
HACSG is listed as a restricted list.
FDA,§184.1490(2000):0.1%.
Preparation
The drug is esterified with p-hydroxybenzoic acid and methanol. The p-hydroxybenzoic acid was added to excess methanol to dissolve, stirring and adding concentrated sulfuric acid slowly. After heating and refluxing 10h, pour into the water to precipitate crystallization, then washed with water, sodium carbonate solution and water, finally obtain the crude product. Recrystallize from water or 25% ethanol to obtain finished product. The yield was 85%. Raw material consumption (kg/t): p-hydroxybenzoic acid 1200, methanol 1000.
Preparation
Produced by the methanol esterification of p-hydroxybenzoic acid in the presence of sulfuric acid. The materials are
heated for distillation 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.
Acute toxicity
Abdomen-mouse LD50: 960 mg/kg
Flammability hazard characteristics
Combustible, excretes spicy smoke from fireground
Storage
Ventilated , low temperature and dry warehouse.
Production Methods
Methylparaben is prepared by the esterification of p-hydroxybenzoic
acid with methanol.
Hazard
Toxic. Use in foods restricted to 0.1%.
Flammability and Explosibility
Nonflammable
Pharmaceutical Applications
Methylparaben is widely used as an antimicrobial preservative in
cosmetics, food products, and pharmaceutical formulations; see
Table I. It may be used either alone or in combination with other methylparaben is the most frequently used antimicrobial preservative.
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. Antimicrobial activity increases
as the chain length of the alkyl moiety is increased, but aqueous
solubility decreases; therefore a mixture of parabens is frequently
used to provide effective preservation. Preservative efficacy is also
improved by the addition of propylene glycol (2–5%), or by using
parabens in combination with other antimicrobial agents such as
imidurea;
Owing to the poor solubility of the parabens, paraben salts
(particularly the sodium salt) are more frequently used in
formulations. However, this raises the pH of poorly buffered
formulations.
Methylparaben (0.18%) together with propylparaben (0.02%)
has been used for the preservation of various parenteral pharmaceutical
formulations;
Biochem/physiol Actions
Methyl 4-hydroxybenzoate, also called methyl paraben or nipagin, comprises the ester of p-hydroxybenzoic acid. It is present naturally in cloudberry, white wine and bourbon vanilla. Methyl 4-hydroxybenzoate has antimicrobial and antifungal functionality and is commercially used as a preservative in the food, cosmetic and pharmaceutical industry. Methyl 4-hydroxybenzoate has cytotoxic effects on keratinocytes in the presence of sunlight. Methyl 4-hydroxybenzoate upon solar irradiation mediates DNA damage and modulates esterase metabolism resulting in skin damage and favors cancer progression. Methyl 4-hydroxybenzoate has estrogenic functionality and upregulates estrogen-related genes.
Safety
Methylparaben and other parabens are widely used as antimicrobial
preservatives in cosmetics and oral and topical pharmaceutical
formulations. Although parabens have also been used as preservatives
in injections and ophthalmic preparations, they are now
generally regarded as being unsuitable for these types of formulations
owing to the irritant potential of the parabens. These
experiences may depend on immune responses to enzymatically
formed metabolites of the parabens in the skin.
Parabens are nonmutagenic, nonteratogenic, and noncarcinogenic.
Sensitization to the parabens is rare, and these compounds do
not exhibit significant levels of photocontact sensitization or
phototoxicity.
Hypersensitivity reactions to parabens, generally of the delayed
type and appearing as contact dermatitis, have been reported.
However, given the widespread use of parabens as preservatives,
such reactions are relatively uncommon; the classification of overstated.
Immediate hypersensitivity reactions following injection of
preparations containing parabens have also been reported.
Delayed-contact dermatitis occurs more frequently when parabens
are used topically, but has also been reported to occur after oral
administration.
Unexpectedly, preparations containing parabens may be used by
patients who have reacted previously with contact dermatitis
provided they are applied to another, unaffected, site. This has
been termed the paraben paradox.
Concern has been expressed over the use of methylparaben in
infant parenteral products because bilirubin binding may be
affected, which is potentially hazardous in hyperbilirubinemic
neonates.
The WHO has set an estimated total acceptable daily intake for
methyl-, ethyl-, and propylparabens at up to 10 mg/kg bodyweight.
LD50 (dog, oral): 3.0 g/kg
LD50 (mouse, IP): 0.96 g/kg
LD50 (mouse, SC): 1.20 g/kg
Carcinogenicity
The carcinogenic potential of
methyl paraben has been studied in rodents. Several studies
are available, but none that expose animals via oral or dermal
routes. No evidence of a carcinogenic effect was observed
following intravenous or subcutaneous injection .
storage
Aqueous solutions of methylparaben at pH 3–6 may be sterilized by
autoclaving at 120°C for 20 minutes, without decomposition.
Aqueous solutions at pH 3–6 are stable (less than 10%
decomposition) for up to about 4 years at room temperature, while
aqueous solutions at pH 8 or above are subject to rapid hydrolysis
(10% or more after about 60 days storage at room temperature);Methylparaben should be stored in a well-closed container in a
cool, dry place.
Purification Methods
Fractionally crystallise the ester from its melt, and recrystallise it from *benzene, then from *benzene/MeOH and dry it over CaCl2 in a vacuum desiccator. [Beilstein 10 IV 360.]
Incompatibilities
The antimicrobial activity of methylparaben and other parabens is
considerably reduced in the presence of nonionic surfactants, such
as polysorbate 80, as a result of micellization.However,
propylene glycol (10%) has been shown to potentiate the
antimicrobial activity of the parabens in the presence of nonionic
surfactants and prevents the interaction between methylparaben
and polysorbate 80.
Incompatibilities with other substances, such as bentonite,
magnesium trisilicate,talc,tragacanth,sodium alginate,
essential oils,sorbitol,and atropine,have been reported. It
also reacts with various sugars and related sugar alcohols.
Absorption of methylparaben by plastics has also been reported;
the amount absorbed is dependent upon the type of plastic and the
vehicle. It has been claimed that low-density and high-density
polyethylene bottles do not absorb methylparaben.
Methylparaben is discolored in the presence of iron and is
subject to hydrolysis by weak alkalis and strong acids.
Regulatory Status
Methylparaben and propylparaben 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 for use as a food additive in Europe. Included in the
FDA Inactive Ingredients Database (IM, IV, and SC injections;
inhalation preparations; ophthalmic preparations; oral capsules,
tablets, solutions and suspensions; otic, rectal, topical, and vaginal
preparations). Included in medicines licensed in the UK. Included in
the Canadian List of Acceptable Non-medicinal Ingredients.
Check Digit Verification of cas no
The CAS Registry Mumber 99-76-3 includes 5 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 2 digits, 9 and 9 respectively; the second part has 2 digits, 7 and 6 respectively.
Calculate Digit Verification of CAS Registry Number 99-76:
(4*9)+(3*9)+(2*7)+(1*6)=83
83 % 10 = 3
So 99-76-3 is a valid CAS Registry Number.
InChI:InChI=1/C8H8O3/c1-5-4-6(9)2-3-7(5)8(10)11/h2-4,9H,1H3,(H,10,11)/p-1
99-76-3Relevant articles and documents
A Mild Heteroatom (O -, N -, and S -) Methylation Protocol Using Trimethyl Phosphate (TMP)-Ca(OH) 2Combination
Tang, Yu,Yu, Biao
, (2022/03/27)
A mild heteroatom methylation protocol using trimethyl phosphate (TMP)-Ca(OH)2combination has been developed, which proceeds in DMF, or water, or under neat conditions, at 80 °C or at room temperature. A series of O-, N-, and S-nucleophiles, including phenols, sulfonamides, N-heterocycles, such as 9H-carbazole, indole derivatives, and 1,8-naphthalimide, and aryl/alkyl thiols, are suitable substrates for this protocol. The high efficiency, operational simplicity, scalability, cost-efficiency, and environmentally friendly nature of this protocol make it an attractive alternative to the conventional base-promoted heteroatom methylation procedures.
Carboxyl Methyltransferase Catalysed Formation of Mono- and Dimethyl Esters under Aqueous Conditions: Application in Cascade Biocatalysis
Ashbrook, Chloe,Carnell, Andrew J.,Goulding, Ellie,Hatton, Harry,Johnson, James R.,Kershaw, Neil M.,McCue, Hannah V.,Rigden, Daniel J.,Ward, Lucy C.
supporting information, (2022/02/21)
Carboxyl methyltransferase (CMT) enzymes catalyse the biomethylation of carboxylic acids under aqueous conditions and have potential for use in synthetic enzyme cascades. Herein we report that the enzyme FtpM from Aspergillus fumigatus can methylate a broad range of aromatic mono- and dicarboxylic acids in good to excellent conversions. The enzyme shows high regioselectivity on its natural substrate fumaryl-l-tyrosine, trans, trans-muconic acid and a number of the dicarboxylic acids tested. Dicarboxylic acids are generally better substrates than monocarboxylic acids, although some substituents are able to compensate for the absence of a second acid group. For dicarboxylic acids, the second methylation shows strong pH dependency with an optimum at pH 5.5–6. Potential for application in industrial biotechnology was demonstrated in a cascade for the production of a bioplastics precursor (FDME) from bioderived 5-hydroxymethylfurfural (HMF).
Site-Selective C-H alkylation of Complex Arenes by a Two-Step Aryl Thianthrenation-Reductive Alkylation Sequence
Granatino, Paola,Lansbergen, Beatrice,Ritter, Tobias
, p. 7909 - 7914 (2021/06/27)
Herein, we present an undirected para-selective two-step C-H alkylation of complex arenes useful for late-stage functionalization. The combination of a site-selective C-H thianthrenation with palladium-catalyzed reductive electrophile cross-coupling grants access to a diverse range of synthetically useful alkylated arenes which cannot be accessed otherwise with comparable selectivity, diversity, and practicality. The robustness of this transformation is further demonstrated by thianthrenium-based reductive coupling of two complex fragments.
Erratum: Site-Selective C-H Alkylation of Complex Arenes by a Two-Step Aryl Thianthrenation-Reductive Alkylation Sequence (J. Am. Chem. Soc. (2021) 143: 21 (7909?7914) DOI: 10.1021/jacs.1c03459)
Granatino, Paola,Lansbergen, Beatrice,Ritter, Tobias
, p. 10477 - 10478 (2021/07/26)
Page 7912. In our previous Communication, we inadvertently drew the substrates derived from the molecule pyriproxyfen with incorrect connectivity of the pyriproxyfen molecule (meta instead of para was drawn), omitted a methylene group from compound 13, and drew an epimer of compound 20 in Scheme 3. These drawing errors have been corrected in the corrected Scheme 3 shown here. As a further clarification, we have commented in the revised Supporting Information about the undefined stereocenter of compound 21. The findings and conclusions of the original communication remain unchanged. We apologize for the errors and for any inconvenience that this may have caused the readers of JACS.
Iron-Catalyzed Halogen Exchange of Trifluoromethyl Arenes**
Dorian, Andreas,Landgreen, Emily J.,Petras, Hayley R.,Shepherd, James J.,Williams, Florence J.
supporting information, p. 10839 - 10843 (2021/06/21)
The facile production of ArCF2X and ArCX3 from ArCF3 using catalytic iron(III)halides is reported, which constitutes the first iron-catalyzed halogen exchange for non-aromatic C?F bonds. Theoretical calculations suggest direct activation of C?F bonds by iron coordination. ArCX3 and ArCF2X products of the reaction are synthetically valuable due to their diversification potential. In particular, chloro- and bromodifluoromethyl arenes (ArCF2Cl, ArCF2Br respectively) provide access to a myriad of difluoromethyl arene derivatives (ArCF2R). To optimize for mono-halogen exchange, a statistical method called Design of Experiments was used. Optimized parameters were successfully applied to electron rich and electron deficient aromatic substrates, and to the late stage diversification of flufenoxuron, a commercial insecticide. These methods are highly practical, being run at convenient temperatures and using inexpensive common reagents.
Discovery and characterization of a novel perylenephotoreductant for the activation of aryl halides
Guo, Baodang,Huang, Shuping,Li, Jia,Li, Min,Liu, Xuanzhong,Rao, Yijian,Wu, Yawen,Yin, Huimin,Yuan, Zhenbo,Zhang, Yan
, p. 111 - 120 (2021/06/16)
To develop a photocatalyst with catalytical activity for substrates with low reactivities is always highly desired. Herein, based on the principle of structure–property relationships, we rationally designed the natural product cercosporin, the naturally occurring perylenequinonoid pigment, to develop a novel organic perylenephotoreductant, hexacetyl reduced cercosporin (HARCP), through structural manipulation. Compared with cercosporin, HARCP shows prominent electrochemical and photophysical characteristics with greatly improved photoreductive activity, fluorescence lifetime and fluorescence quantum yield. These properties allowed HARCP as a powerful photoreductant to efficiently realize a series of benchmark reactions, including photoreduction, alkoxylation and hydroxylation to construct C–H and C–O bonds using aryl halides as substrates under mild conditions, all of which have never been achieved by the same photocatalyst. Thus, this study well supports the notion that the principle between structural manipulation and photocatalytic activity is of great significance to design customized photocatalysts for photoredox chemistry.
Biocatalytic Cross-Coupling of Aryl Halides with a Genetically Engineered Photosensitizer Artificial Dehalogenase
Fu, Yu,Huang, Jian,Wu, Yuzhou,Liu, Xiaohong,Zhong, Fangrui,Wang, Jiangyun
supporting information, p. 617 - 622 (2021/02/03)
Devising artificial photoenzymes for abiological bond-forming reactions is of high synthetic value but also a tremendous challenge. Disclosed herein is the first photobiocatalytic cross-coupling of aryl halides enabled by a designer artificial dehalogenase, which features a genetically encoded benzophenone chromophore and site-specifically modified synthetic NiII(bpy) cofactor with tunable proximity to streamline the dual catalysis. Transient absorption studies suggest the likelihood of energy transfer activation in the elementary organometallic event. This design strategy is viable to significantly expand the catalytic repertoire of artificial photoenzymes for useful organic transformations.
Coordination Polymers as a Functional Material for the Selective Molecular Recognition of Nitroaromatics and ipso-Hydroxylation of Arylboronic Acids
Bhasin, K. K.,Husain, Ahmad,Kumar, Girijesh,Rani, Pooja
, (2021/12/06)
We report the synthesis and structural characterization of two coordination polymers (CPs), namely; [{Zn(L)(DMF)4} ? 2BF4]α (1) and [{Cd(L)2(Cl)2} ? 2H2O]α (2) (where L=N2,N6-di(pyridin-4-yl)naphthalene-2,6-dicarboxamide). Crystal packing of 1 reveals the existence of channels running along the b- and c-axis filled by the ligated DMF and lattice anions, respectively. Whereas, crystal packing of 2 reveals that the metallacycles of each 1D chain are intercalating into the groove of adjacent metallacycles resulting in the stacking of 1D loop-chains to form a sheet-like architecture. In addition, both 1 and 2 were exploited as multifunctional materials for the detection of nitroaromatic compounds (NACs) as well as a catalyst in the ipso-hydroxylation of aryl/heteroarylboronic acids. Remarkably, 1 and 2 showed high fluorescence stability in an aqueous medium and displayed a maximum 88% and 97% quenching efficiency for 4-NPH, respectively among all the investigated NACs. The mechanistic investigation of NACs recognition suggested that the fluorescence quenching occurred via electron as well as energy transfer process. Furthermore, the ipso-hydroxylation of aryl/heteroarylboronic acids in presence of 1 and 2 gave up to 99% desired product yield within 15 min in our established protocol. In both cases, 1 and 2 are recyclable upto five cycles without any significant loss in their efficiency.
Isotruxene-based porous polymers as efficient and recyclable photocatalysts for visible-light induced metal-free oxidative organic transformations
Zhang, Haowen,Zhang, Xiao,Zheng, Ying,Zhou, Cen
supporting information, p. 8878 - 8885 (2021/11/27)
Two new isotruxene-based porous polymers were prepared and demonstrated to be highly efficient, metal-free heterogeneous photocatalysts for oxidative transformations using air as the mild oxidant under visible-light irradiation. Both catalysts show excellent recyclability. In addition, the reactions can be performed in water, further indicating the greenness of this method. This journal is
Building a Pyrazole–Benzothiadiazole–Pyrazole Photosensitizer into Metal–Organic Frameworks for Photocatalytic Aerobic Oxidation
Jin, Ji-Kang,Wu, Kun,Liu, Xin-Yi,Huang, Guo-Quan,Huang, Yong-Liang,Luo, Dong,Xie, Mo,Zhao, Yifang,Lu, Weigang,Zhou, Xiao-Ping,He, Jian,Li, Dan
supporting information, p. 21340 - 21349 (2021/12/17)
Charge separation plays a crucial role in regulating photochemical properties and therefore warrants consideration in designing photocatalysts. Metal–organic frameworks (MOFs) are emerging as promising candidates for heterogeneous photocatalysis due to their structural designability and tunability of photon absorption. Herein, we report the design of a pyrazole–benzothiadiazole–pyrazole organic molecule bearing a donor–acceptor–donor conjugated π-system for fast charge separation. Further attempts to integrate such a photosensitizer into MOFs afford a more effective heterogeneous photocatalyst (JNU-204). Under visible-light irradiation, three aerobic oxidation reactions involving different oxygenation pathways were achieved on JNU-204. Recycling experiments were conducted to demonstrate the stability and reusability of JNU-204 as a robust heterogeneous photocatalyst. Furthermore, we illustrate its applications in the facile synthesis of pyrrolo[2,1-a]isoquinoline-containing heterocycles, core skeletons of a family of marine natural products. JNU-204 is an exemplary MOF platform with good photon absorption, suitable band gap, fast charge separation, and extraordinary chemical stability for proceeding with aerobic oxidation reactions under visible-light irradiation.
