Q1: What is dimethyl phthalate? What are its common aliases and molecular formula?
Dimethyl phthalate, abbreviated as DMP, is the most fundamental compound in the phthalate ester family. Its common aliases include 1,2-benzenedicarboxylic acid dimethyl ester. It has a chemical molecular formula of C₁₀H₁₀O₄ and a molecular weight of 194.18. As a synthetic fine chemical organic ester product, it is widely used as a plasticizer and solvent intermediate in industrial production.
Q2: What are the differences between dimethyl phthalate and the commonly used diethyl phthalate and dibutyl phthalate?
All three substances belong to phthalate esters, and their core differences lie in the length of alkyl carbon chains, which directly determines their properties and applications. DMP has the shortest carbon chain and the smallest molecular weight, featuring relatively high volatility and weak plasticizing flexibility, but excellent solubility and permeability. Diethyl phthalate (DEP) has intermediate properties between the other two. Dibutyl phthalate (DBP) has a longer carbon chain, with better plasticizing effect and lower volatility, and is mostly used for plastic softening. With the core advantage of high solubility, DMP is mainly applied as a solvent, insect repellent and coating auxiliary agent rather than a mainstream plastic plasticizer.
Q3: What are the appearance, odor and conventional physical state of dimethyl phthalate?
Under normal temperature and atmospheric pressure, dimethyl phthalate is a colorless transparent oily liquid without turbidity or precipitate. It has a slight special aromatic odor and no pungent stench. It will crystallize slowly at low temperatures with a relatively high freezing point, which is a typical characteristic distinguishing it from other phthalate esters.
Q4: What are the core physical and chemical parameters of dimethyl phthalate?
The core commonly used parameters are as follows: melting point 0℃, boiling point 283℃, relative density 1.190 (20℃), refractive index 1.515～1.517, flash point 146℃ (closed cup). It is slightly soluble in water and easily soluble in most organic solvents such as ethanol, ether, acetone, benzene and chloroform. It possesses good film-forming, permeable and dispersing properties, and maintains stable chemical properties at room temperature.
Q5: What is the chemical stability of dimethyl phthalate? What chemical reactions will it undergo?
It is stable under normal temperature and dry conditions, with no easy decomposition or oxidation. Under heating conditions with strong acid or strong alkali, it will undergo hydrolysis reaction to generate phthalic acid and methanol. It can undergo transesterification reaction with alcohols, as well as benzene ring substitution reactions such as nitration and sulfonation. Long-term exposure to high temperature and sunlight will cause slow oxidative discoloration and reduce product purity.
Q6: What is the mainstream production process of dimethyl phthalate?
The mainstream industrial production process is the esterification reaction of phthalic anhydride and methanol. Using phthalic anhydride and industrial methanol as raw materials, under the action of acidic catalysts (concentrated sulfuric acid, p-toluenesulfonic acid, etc.), the finished product is obtained through heating reflux esterification, dehydration, rectification purification, decolorization and filtration. This process is mature with high yield and few impurities, and is the only mainstream industrialized process at present.
Q7: What are the common industrial grade specifications of DMP products?
There are three main grades of DMP products on the market: First, industrial grade with purity ≥99.0% and low impurity content, suitable for most industrial production scenarios. Second, refined grade with purity ≥99.5% and transparent color, applied in fine chemical industry and high-end coatings. Third, reagent grade (analytical pure) with purity ≥99.8% and no heavy metal impurities, used for laboratory testing and scientific research experiments.
Q8: What are the core application fields of dimethyl phthalate?
DMP has a wide range of uses, and its core applications are concentrated in four major fields. First, solvents and auxiliaries: it serves as an excellent solvent for cellulose resin, acrylic resin and nitrocellulose lacquer, improving the adhesion and flexibility of paint films in coatings and ink industries. Second, insect repellent: it is a high-efficiency raw material for mosquito repellents, applicable in mosquito repellent products and agricultural and forestry insect repellent preparations. Third, chemical intermediates: used for the synthesis of other phthalate esters, spices and pharmaceutical intermediates. Fourth, other industries: applied as paper softeners, lubricants and synthetic plasticizers, and also used in cosmetics and daily chemical auxiliaries within the scope of compliance.
Q9: Why is DMP rarely used for PVC plastic plasticization?
Compared with plasticizers such as DBP and DOP, DMP has a small molecular weight and high volatility, with general compatibility with PVC resin. It is prone to precipitation and volatilization during long-term use, resulting in hardening, cracking and aging of plastic products and poor plasticization durability. Therefore, it is rarely used as a main plasticizer for PVC in industry, only as an auxiliary additive, and its core applications are concentrated in solvents and insect repellent fields.
Q10: Is dimethyl phthalate toxic? What is its toxicity grade and hazards?
DMP is a low-toxic chemical product, not a highly toxic or super-toxic substance, but direct contact and ingestion are prohibited. It has extremely low acute toxicity, with an oral LD50 of approximately 6900mg/kg in rats. Long-term repeated contact or excessive intake may cause slight burden on the liver and kidneys and mild irritation to skin and mucous membranes. At present, there is no clear evidence of carcinogenicity or teratogenicity. However, it is a restricted phthalate ester and is strictly prohibited from being used in children’s products and food contact materials.
Q11: What discomfort will human body contact with DMP cause? What are the emergency treatment methods?
1. Skin contact: May cause slight redness, dryness and itching. Immediately take off contaminated clothes and rinse the skin with running clean water. 2. Eye contact: May cause slight stinging and dryness. Continuously flush the eyes with a large amount of normal saline or clean water for 10-15 minutes, and seek medical attention in time if discomfort worsens. 3. Ingestion: May cause nausea and abdominal distension. Do not induce vomiting, dilute with warm water and seek medical treatment promptly. 4. Inhalation: High-concentration steam may irritate the respiratory tract. Immediately move to a well-ventilated place and keep breathing unobstructed.
Q12: What are the storage requirements for dimethyl phthalate?
It shall be hermetically stored in a cool, dry and ventilated special chemical warehouse with the storage temperature ≤30℃. Keep away from fire sources and heat sources and avoid direct sunlight. It is forbidden to store together with strong acids, strong alkalis, strong oxidants and edible chemicals. The warehouse shall be equipped with anti-seepage, fire-proof and explosion-proof facilities with anti-corrosion ground treatment. Keep the package intact to prevent leakage, and regularly check for delamination and discoloration during long-term storage.
Q13: What are the specifications and taboos for DMP transportation?
DMP is an ordinary chemical product, not a dangerous good, but its transportation shall comply with chemical transportation specifications. It is packed in sealed iron drums or plastic drums. Handle with care during loading and unloading to prevent package damage and leakage. Avoid exposure to sunlight, high temperature and severe bumping during transportation. Mixed transportation with flammable and explosive, corrosive and food goods is strictly prohibited. Transport vehicles shall have chemical transportation qualifications and be equipped with emergency protective supplies.
Post time: Jul-31-2026