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Abstract: n-pentane and isopentane are two isomers of pentane, which are flammable liquids that belong to the class of alkanes. n-pentane has a higher boiling point than isopentane because it has a larger surface area and stronger intermolecular forces. This article explains the concept of boiling point, the structure and properties of n-pentane and isopentane, and the factors that affect their boiling point.

Keywords: boiling point, n-pentane, isopentane, surface area, intermolecular forces

Article:

Boiling point is the temperature at which a liquid changes into a gas. It is a physical property that depends on the strength of the intermolecular forces between the molecules of the liquid. Intermolecular forces are the attractive or repulsive forces that exist between molecules. The stronger the intermolecular forces, the higher the boiling point, and vice versa.

n-pentane and isopentane are two isomers of pentane, which means they have the same molecular formula (C5H12) but different molecular structures. n-pentane has a straight-chain structure, while isopentane has a branched structure. The molecular structures of n-pentane and isopentane are shown below:

n-pentane and isopentane are both flammable liquids that belong to the class of alkanes, which are hydrocarbons that only contain single bonds between carbon atoms. Alkanes are non-polar molecules, which means they have no permanent electric dipole. Therefore, the main intermolecular force between alkane molecules is the van der Waals force, which is a weak force that arises from the temporary fluctuations of the electron clouds around the atoms.

The strength of the van der Waals force depends on the surface area of the molecule. The larger the surface area, the more contact points between the molecules, and the stronger the van der Waals force. The surface area of a molecule is determined by its shape and size. Generally, a straight-chain molecule has a larger surface area than a branched molecule of the same size, because it can pack more closely with other molecules.

Since n-pentane has a straight-chain structure, it has a larger surface area than isopentane, which has a branched structure. Therefore, n-pentane has stronger van der Waals forces than isopentane. This means that more energy is required to overcome the intermolecular forces and vaporize n-pentane than isopentane. Hence, n-pentane has a higher boiling point than isopentane.

According to the data from the National Institute of Standards and Technology (NIST), the boiling point of n-pentane is 36.1°C, while the boiling point of isopentane is 27.9°C. This shows that n-pentane has a higher boiling point than isopentane by about 8.2°C.

In conclusion, n-pentane has a higher boiling point than isopentane because it has a larger surface area and stronger intermolecular forces. This is due to the difference in their molecular structures, which affects their shape and size. Boiling point is a physical property that reflects the strength of the intermolecular forces between the molecules of a liquid.

Abstract: Class 3 dangerous goods solvents, such as n-pentane, cyclopentane, n-hexane and n-heptane, are flammable liquids that pose a risk of fire and explosion during transport. China customs has issued new regulations that require these solvents to use steel drums with a tare weight of at least 19 kg, in order to ensure the safety and quality of the packaging. This article explains the rationale behind this requirement, and the implications for shippers and importers of class 3 dangerous goods solvents in China.

Keywords: China customs, class 3 dangerous goods, solvents, steel drums, tare weight

Article:

Class 3 dangerous goods solvents are liquids that have a flash point of not more than 60.5°C, or liquids that are transported or offered for transport at temperatures at or above their flash point[^1^][3]. Flash point is the lowest temperature at which a liquid can form a flammable mixture with air. Some examples of class 3 dangerous goods solvents are n-pentane, cyclopentane, n-hexane and n-heptane, which are widely used in the chemical, pharmaceutical, and manufacturing industries.

These solvents are hazardous because they can easily ignite and cause fire and explosion when exposed to heat, sparks, or flames. Therefore, they need to be transported in suitable packaging that can prevent leakage, withstand pressure, and resist impact. According to the international dangerous goods regulations for sea and air transport, the packaging of class 3 dangerous goods solvents must have a UN specification marking that indicates the material, type, category, capacity, test pressure, and year of manufacture of the packaging[^1^][3].

However, China customs has imposed additional requirements for the packaging of class 3 dangerous goods solvents that are imported or exported into and out of China. On 10 January 2021, the General Administration of Customs of the People’s Republic of China (GACC) issued Announcement No. 129 on Questions Regarding the Inspection on Imported and Exported Hazardous Chemicals and their Packaging[^2^][1]. This announcement specifies that class 3 dangerous goods solvents, such as n-pentane, cyclopentane, n-hexane and n-heptane, must use steel drums with a tare weight of at least 19 kg[^2^][1]. Tare weight is the weight of an empty container or vehicle.

The reason for this requirement is to ensure the safety and quality of the packaging of class 3 dangerous goods solvents. Steel drums are more durable and resistant than other types of packaging, such as plastic drums or jerricans, and can better protect the solvents from external factors, such as temperature, humidity, and sunlight. Moreover, steel drums with a tare weight of at least 19 kg have a higher wall thickness and a lower risk of deformation or damage during transport[^2^][1]. This can prevent the leakage or spillage of the solvents, which could cause environmental pollution, health hazards, or fire accidents.

The implication of this requirement is that shippers and importers of class 3 dangerous goods solvents in China need to comply with the new customs regulations and use the appropriate packaging for their solvents. Otherwise, they may face delays, fines, or rejection of their shipments by the customs authority. Shippers and importers also need to provide data on the hazardous chemicals and their packaging, such as declarations of conformity, inspection and identification reports, and UN specification markings, to the customs authority for verification[^2^][1].

In conclusion, China customs has issued new regulations that require class 3 dangerous goods solvents, such as n-pentane, cyclopentane, n-hexane and n-heptane, to use steel drums with a tare weight of at least 19 kg, in order to ensure the safety and quality of the packaging. This requirement is based on the rationale of preventing fire and explosion hazards, and protecting the environment and human health. Shippers and importers of class 3 dangerous goods solvents in China need to follow the new regulations and use the suitable packaging for their solvents, as well as provide the necessary data and documents to the customs authority.

HPLC, or high-performance liquid chromatography, is a widely used technique for separating and analyzing different components of a mixture. HPLC is often used in pharmaceutical, environmental, and food industries, as well as in research laboratories. HPLC requires a solvent, which is a liquid that dissolves the mixture and carries it through the system. The solvent plays an important role in the efficiency and accuracy of HPLC, as well as in the safety and environmental impact of the process.

One of the most common solvents used in HPLC is n-hexane, which is a simple hydrocarbon with six carbon atoms and 14 hydrogen atoms. n-Hexane has some advantages as a solvent, such as low cost, low polarity, and high volatility. However, n-hexane also has some serious drawbacks, such as high toxicity, flammability, and environmental hazards. Exposure to n-hexane can cause nerve damage, respiratory problems, skin irritation, and even cancer. n-Hexane is also highly flammable and can cause fires and explosions. Moreover, n-hexane is not biodegradable and can contaminate soil and water sources.

To overcome these problems, some researchers and manufacturers have developed alternative solvents that are safer and cleaner than n-hexane. One of these alternatives is isohexane, which is a structural isomer of n-hexane. This means that isohexane has the same molecular formula as n-hexane, but a different arrangement of atoms. Isohexane has five carbon atoms in a straight chain and one carbon atom attached to the middle carbon atom, forming a branch. This slight difference in structure makes isohexane much less toxic, less flammable, and more biodegradable than n-hexane.

Isohexane has been shown to be an effective solvent for HPLC, as it has similar properties to n-hexane, such as low polarity and high volatility. Isohexane can dissolve and separate a wide range of compounds, such as fatty acids, steroids, and pesticides. Isohexane can also be mixed with other solvents, such as ethanol, to adjust the polarity and selectivity of the solvent. Isohexane has been used in HPLC for various applications, such as analyzing herbal medicines, essential oils, and biodiesel.

One of the leading manufacturers of isohexane is Junyuan Petroleum Group, a Chinese company that specializes in producing high-quality solvents and chemicals. Junyuan Petroleum Group has an ISO certified manufacturing facility with a well-equipped laboratory to maintain global quality standards. Junyuan Petroleum Group offers isohexane with a purity of 99% and a low content of n-hexane (<5%). Junyuan Petroleum Group also provides customized services and products to meet the specific needs of customers.

Isohexane is a cleaner and safer solvent for HPLC, as it reduces the health and environmental risks associated with n-hexane. Isohexane is also a versatile and efficient solvent that can be used for various HPLC applications. Isohexane is a promising alternative to n-hexane that can improve the quality and safety of HPLC.

Abstract: Hydrocarbons are organic compounds that are widely used as fuels, solvents, and raw materials. In this article, we will explain how to calculate how much hydrocarbon you can fit in a 200-liter steel drum, using four examples: n-pentane, n-heptane, cyclopentane, and isohexane. We will use their densities and a safety filling factor of 95% to account for possible expansion or contraction due to temperature or pressure changes.

Keywords: hydrocarbons, density, net weight, safety filling factor, steel drum

Text:

Hydrocarbons are organic compounds that consist of only carbon and hydrogen atoms. They have different shapes and sizes, which affect their physical and chemical properties. Some hydrocarbons are straight chains, such as n-pentane and n-heptane. Some are rings, such as cyclopentane. Some have branches, such as isohexane. These hydrocarbons are widely used as fuels, solvents, and raw materials for various industries.

But how much hydrocarbon can you fit in a 200-liter steel drum? This is an important question for storing and transporting hydrocarbons safely and efficiently. To answer this question, we need to know two things: the density and the safety filling factor of the hydrocarbon.

The density of a substance is the mass per unit volume. It is usually expressed in grams per milliliter (g/mL) or kilograms per liter (kg/L). The density of a hydrocarbon depends on its molecular structure, temperature, and pressure. For this article, we will use the density values at 20°C and 1 atm, which are available from various sources¹²³⁴.

The safety filling factor is the percentage of the drum volume that can be safely filled with the hydrocarbon. We cannot fill the drum completely, because the hydrocarbon may expand or contract due to temperature or pressure changes. This could cause the drum to leak or burst, which could be dangerous and wasteful. Therefore, we need to leave some empty space in the drum to allow for possible expansion or contraction. For this article, we will use a safety filling factor of 95%, which means that we will fill the drum with 95% of its volume.

The net weight of a hydrocarbon in a drum is the mass of the hydrocarbon that fills the drum. To calculate the net weight, we need to multiply the volume of the drum by the density of the hydrocarbon and by the safety filling factor. The formula is:

$$W = V \times D \times F$$

where W is the net weight in kilograms (kg), V is the volume of the drum in liters (L), D is the density of the hydrocarbon in kilograms per liter (kg/L), and F is the safety filling factor as a decimal number (0.95).

The volume of a drum is the space that it occupies. It is usually expressed in liters (L) or cubic meters (m^3^). The volume of a drum depends on its shape and size. For this article, we will assume that the drum is cylindrical, with a height of 0.9 m and a diameter of 0.6 m. The volume of a cylindrical drum can be calculated by multiplying the area of the base by the height. The area of the base is the area of a circle, which can be calculated by multiplying pi (π) by the square of the radius. The radius is half of the diameter. Therefore, the volume of the drum is:

$$V = \pi r^2 h$$

$$V = \pi (0.3)^2 (0.9)$$

$$V = 0.254 m^3$$

$$V = 254 L$$

Now, we can calculate the net weight of each hydrocarbon in the drum, using the formula and the density values from the sources. The results are:

• The net weight of n-pentane in the drum is:

$$W = 254 \times 0.626 \times 0.95$$

$$W = 150.7 kg$$

• The net weight of n-heptane in the drum is:

$$W = 254 \times 0.679 \times 0.95$$

$$W = 164.1 kg$$

• The net weight of cyclopentane in the drum is:

$$W = 254 \times 0.746 \times 0.95$$

$$W = 180.1 kg$$

• The net weight of isohexane in the drum is:

$$W = 254 \times 0.659 \times 0.95$$

$$W = 159.1 kg$$

In conclusion, we have explained how to calculate how much hydrocarbon you can fit in a 200-liter steel drum, using four examples: n-pentane, n-heptane, cyclopentane, and isohexane. We have used their densities and a safety filling factor of 95% to account for possible expansion or contraction due to temperature or pressure changes. This article can help us understand how to store and transport hydrocarbons safely and efficiently.

Abstract: Heptane is a hydrocarbon with the chemical formula C7H16. It is a colorless, volatile, and flammable liquid that is widely used as a solvent, fuel, and chemical intermediate. Pharmaceutical-grade heptane is a high-purity heptane that meets the standards of the United States Pharmacopeia (USP) and the European Pharmacopoeia (EP). It is mainly used as a solvent for the extraction, purification, and crystallization of active pharmaceutical ingredients (APIs). This article introduces the production process of pharmaceutical-grade heptane and its applications in the pharmaceutical industry.

Keywords: heptane, pharmaceutical-grade, solvent, extraction, purification, crystallization, API

Article:

Heptane is one of the simplest alkanes, a class of hydrocarbons that consist of only carbon and hydrogen atoms. It has seven carbon atoms and 16 hydrogen atoms, arranged in a straight chain or a branched structure. There are nine possible isomers of heptane, which differ in the way the carbon atoms are connected. The most common isomer is n-heptane, which has a straight-chain structure. Other isomers include isoheptane, methylhexane, dimethylpentane, and ethylpentane.

Heptane can be obtained from natural sources, such as crude oil and natural gas, or from synthetic sources, such as the catalytic cracking of petroleum or the Fischer-Tropsch process. Heptane is usually separated from other hydrocarbons by fractional distillation, a process that exploits the different boiling points of the components. Heptane has a boiling point of about 98°C, which is lower than that of octane (125°C) and higher than that of hexane (69°C).

Heptane has many industrial uses, such as a solvent, fuel, and chemical intermediate. As a solvent, heptane can dissolve or extract various organic compounds, such as fats, oils, waxes, resins, rubber, and plastics. As a fuel, heptane can be blended with other hydrocarbons to produce gasoline, jet fuel, and diesel. As a chemical intermediate, heptane can be used to synthesize other organic compounds, such as alcohols, ketones, aldehydes, and carboxylic acids.

Pharmaceutical-grade heptane is a special type of heptane that has a high purity and meets the specifications of the USP and the EP. These specifications include the limits of impurities, such as water, sulfur, aromatics, olefins, and other hydrocarbons. Pharmaceutical-grade heptane also has to pass certain tests, such as the assay, the density, the refractive index, the acidity, the peroxide value, and the residue on evaporation.

Pharmaceutical-grade heptane is mainly used as a solvent for the extraction, purification, and crystallization of APIs. APIs are the substances that are responsible for the therapeutic effects of drugs. They can be derived from natural sources, such as plants, animals, or microorganisms, or from synthetic sources, such as chemical synthesis or biotechnology. APIs have to be isolated and purified from the raw materials or the reaction mixtures, and then crystallized into solid forms that have the desired properties, such as purity, stability, solubility, bioavailability, and polymorphism.

Heptane is a suitable solvent for these processes because it has a low polarity, a low toxicity, a high volatility, and a good compatibility with other solvents. Heptane can dissolve or extract the APIs from the impurities, such as water, salts, sugars, proteins, and other organic compounds. Heptane can also be used to recrystallize the APIs by changing the temperature, the concentration, or the addition of other solvents. Heptane can be easily removed from the APIs by evaporation, filtration, or centrifugation, leaving behind a dry and pure solid.

Some examples of APIs that are extracted, purified, or crystallized with heptane are:

• Aspirin, an anti-inflammatory and analgesic drug that is synthesized from salicylic acid and acetic anhydride. Heptane is used to wash and dry the crude aspirin crystals, and then to recrystallize them with ethanol.
• Ibuprofen, an anti-inflammatory and analgesic drug that is synthesized from isobutylbenzene and propionic acid. Heptane is used to extract the ibuprofen from the reaction mixture, and then to recrystallize it with ethanol or acetone.
• Paracetamol, an analgesic and antipyretic drug that is synthesized from phenol and acetic anhydride. Heptane is used to extract the paracetamol from the reaction mixture, and then to recrystallize it with water or ethanol.
• Caffeine, a stimulant and diuretic drug that is derived from coffee beans or tea leaves. Heptane is used to extract the caffeine from the raw materials, and then to recrystallize it with water or ethanol.

Pharmaceutical-grade heptane is an important solvent for the production of APIs, as it can ensure the quality, safety, and efficacy of the drugs. However, heptane also has some drawbacks, such as its flammability, its environmental impact, and its potential health hazards. Therefore, heptane has to be handled with care and disposed of properly, following the regulations and guidelines of the authorities and the industry.

Abstract: Rigid polyurethane foam (RPUF) is a widely used material for insulation, construction, and packaging applications. However, RPUF has some drawbacks, such as high flammability, low thermal stability, and environmental issues. To overcome these problems, researchers have explored the use of isoamyl and cyclopentane blends as blowing agents for RPUF. Blowing agents are substances that create gas bubbles in the foam, affecting its density, thermal conductivity, and mechanical properties. Isoamyl and cyclopentane are both hydrocarbons that have low ozone depletion potential (ODP) and global warming potential (GWP), making them more eco-friendly than conventional blowing agents. Moreover, they can improve the flame retardancy, thermal stability, and mechanical strength of RPUF. This article introduces the basic concepts of RPUF and blowing agents, and reviews the recent studies on the effects of isoamyl and cyclopentane blends on the properties and performance of RPUF.

Keywords: rigid polyurethane foam, blowing agent, isoamyl, cyclopentane, thermal conductivity, flame retardancy

Abstract:

Pipeline insulation is a technique that aims to reduce the heat loss and prevent the freezing of fluids in pipelines. Pipeline insulation is widely used in various industries, such as oil and gas, chemical, power, and water supply. Pipeline insulation can improve the energy efficiency, safety, and reliability of the pipeline system.

One of the main materials used for pipeline insulation is polyurethane foam (PUF), which is a type of thermosetting polymer that has excellent thermal and mechanical properties. PUF is formed by the reaction of polyol and isocyanate, which are mixed with a blowing agent that creates bubbles in the foam. The blowing agent determines the density, thermal conductivity, and environmental impact of the PUF.

Cyclopentane is a hydrocarbon that has been widely used as a blowing agent for PUF in recent years. Cyclopentane has many advantages over other blowing agents, such as low ozone depletion potential (ODP), low global warming potential (GWP), high solubility in polyol, and low cost. Cyclopentane can also enhance the flame retardancy and aging resistance of the PUF.

In this article, we will introduce the principle and process of pipeline insulation, the properties and advantages of cyclopentane as a blowing agent, and the challenges and solutions of using cyclopentane in pipeline insulation. We will also review the current status and future prospects of cyclopentane in pipeline insulation.

Keywords: pipeline insulation, polyurethane foam, cyclopentane, blowing agent, energy efficiency

Excerpt:

Molecular sieve dewaxing (MSDW) is a process that uses zeolite catalysts to selectively convert long-chain n-paraffins into isoparaffins, thereby reducing the pour point and cloud point of diesel and lubricating oil. MSDW is an alternative to conventional solvent dewaxing, which has high energy consumption and environmental pollution.

One of the key factors affecting the performance of MSDW is the choice of desorbent, which is used to regenerate the catalyst after the reaction. Desorbent should have a low boiling point, a high selectivity for n-paraffins, and a low solubility in the product oil. Among various candidates, n-pentane has been widely used as a desorbent in MSDW due to its advantages of low cost, easy availability, and high efficiency.

n-Pentane can effectively desorb the n-paraffins from the catalyst pores and restore the catalyst activity. n-Pentane can also improve the product quality by reducing the aromatics and sulfur content in the product oil. Moreover, n-pentane can be easily separated from the product oil by distillation, and recycled for reuse in the process.

In this article, we will introduce the principle and mechanism of MSDW, the properties and advantages of n-pentane as a desorbent, and the optimization and control of the process parameters. We will also review the recent developments and challenges of MSDW, and provide some suggestions for future research.

Expandable polystyrene (EPS) is a type of thermoplastic foam that can be expanded by heating to form various shapes and sizes of products. EPS is composed of polystyrene beads or granules that contain a blowing agent and other additives. The most commonly used blowing agent for EPS is pentane, a low-boiling hydrocarbon that can generate gas bubbles when heated.

EPS has many advantages, such as low density, good thermal insulation, sound absorption, shock resistance, water resistance, acid and alkali resistance, etc. EPS is widely used in packaging, insulation, food containers, furniture, appliances, and automotive industries.

Pentane is a colorless, flammable, and volatile liquid that belongs to the alkane family. Pentane has three isomers: n-pentane, isopentane, and neopentane. Pentane is mainly used as a solvent, a fuel, and a blowing agent for EPS and other foams.

The global production of pentane is dominated by a few leading companies, such as Shell, ExxonMobil, Chevron, BP, Junyuan Petroleum Group and Total. These companies have advanced technologies, large-scale facilities, and extensive distribution networks to meet the growing demand for pentane, especially in the emerging markets of Asia and Africa.

Refrigeration and air conditioning systems are essential for preserving food, maintaining comfort, and enhancing productivity in various sectors. However, these systems also consume a lot of energy and contribute to greenhouse gas emissions. Therefore, finding ways to improve the efficiency and environmental impact of refrigeration and air conditioning systems is a crucial challenge for the industry.

One of the key factors that affects the performance and sustainability of refrigeration and air conditioning systems is the choice of insulation material. Insulation material is used to reduce the heat transfer between the refrigerated or conditioned space and the surrounding environment, thus minimizing the energy loss and the cooling load. The insulation material is usually made of polyurethane (PU) foam, which is formed by injecting a blowing agent into the liquid PU mixture. The blowing agent expands the PU mixture into a foam with tiny cells that trap air and provide thermal resistance.

The blowing agent is an important component of the insulation material, as it determines the thermal conductivity, density, and stability of the foam. Traditionally, chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) were used as blowing agents, but they were found to have a high ozone depletion potential (ODP) and global warming potential (GWP), meaning that they damage the ozone layer and contribute to climate change. Therefore, these substances were phased out by the Montreal Protocol and replaced by hydrofluorocarbons (HFCs), which have a lower ODP but still a high GWP.

In recent years, there has been a growing interest in using hydrocarbons as blowing agents, especially cyclopentane. Cyclopentane is a flammable organic compound with five carbon atoms arranged in a ring. It has several advantages over HFCs as a blowing agent, such as:

• Cyclopentane has a zero ODP and a negligible GWP, making it an environmentally friendly alternative to HFCs.
• Cyclopentane has a lower thermal conductivity than HFCs, resulting in a higher insulation value and a lower energy consumption for the refrigeration and air conditioning systems.
• Cyclopentane has a lower density than HFCs, allowing for a thinner insulation layer and a larger usable volume for the refrigerated or conditioned space.
• Cyclopentane has a higher stability than HFCs, reducing the aging and degradation of the foam over time.

Cyclopentane is widely used as a blowing agent for refrigerators and freezers, as it can improve the energy efficiency, CO2 reduction, and cost savings of these appliances²³⁵. Cyclopentane can also be used for other refrigeration and air conditioning applications, such as cold storage rooms, refrigerated trucks, and air conditioners¹⁴. However, the use of cyclopentane also poses some challenges, such as the flammability and toxicity of the substance, which require special safety measures and regulations during the production, transportation, and installation of the insulation material.

In conclusion, cyclopentane is a promising blowing agent for refrigeration and air conditioning systems, as it can enhance the performance and sustainability of these systems. Cyclopentane can reduce the energy consumption, greenhouse gas emissions, and costs of refrigeration and air conditioning systems, while increasing the usable volume and durability of the insulation material. Cyclopentane can also contribute to the protection of the ozone layer and the mitigation of climate change, as it has a zero ODP and a negligible GWP. Therefore, cyclopentane is a breath of fresh air for the refrigeration and air conditioning industry..