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n-Heptane is a pure form of heptane, a common solvent and fuel component. It has a special role in measuring the octane rating of gasoline and in separating chiral compounds.

Heptane is a simple organic compound with the chemical formula C$_7$H$_{16}$. It is a colorless liquid that smells like gasoline and is highly flammable. Heptane is widely used as a solvent in laboratories and industries, as it can dissolve many non-polar substances. It is also a component of gasoline, as it can be easily refined from crude oil.

However, not all heptane molecules are the same. There are different ways to arrange the seven carbon atoms and the 16 hydrogen atoms in a heptane molecule, resulting in different shapes and properties. These different forms of heptane are called isomers, and there are nine of them in total.

One of the isomers of heptane is n-heptane, which stands for normal heptane. This is the simplest and most symmetrical form of heptane, where the seven carbon atoms are arranged in a straight chain. n-Heptane has some unique characteristics that make it important for chemistry.

First, n-heptane is the standard for measuring the octane rating of gasoline. The octane rating is a measure of how well a fuel can resist knocking, which is a phenomenon where the fuel ignites too early in the engine, causing damage and reducing efficiency. n-Heptane is very prone to knocking, as it burns very quickly and explosively. Therefore, it is assigned a octane rating of zero, meaning the worst possible fuel for an engine. On the other hand, iso-octane, another isomer of octane (C$_8$H$_{18}$), is very resistant to knocking, as it burns more slowly and smoothly. Therefore, it is assigned a octane rating of 100, meaning the best possible fuel for an engine. Other fuels are compared to these two extremes, and their octane rating is calculated as the percentage of iso-octane in a mixture with n-heptane that has the same knocking behavior. For example, a gasoline with an octane rating of 87 means that it behaves like a mixture of 87% iso-octane and 13% n-heptane.

Second, n-heptane is useful for separating chiral compounds. Chiral compounds are molecules that have two forms that are mirror images of each other, like your left and right hands. These forms are called enantiomers, and they can have different effects on living organisms. For example, one enantiomer of a drug may be beneficial, while the other may be harmful. Therefore, it is important to be able to separate and identify the enantiomers of a chiral compound. One way to do this is by using a chiral column, which is a tube filled with a material that can distinguish between the enantiomers. The chiral compound is dissolved in a solvent, such as n-heptane, and passed through the column. The enantiomers will interact differently with the material, and will come out of the column at different times. This is called chromatography, and it is a widely used technique for separating and analyzing mixtures.

n-Heptane is a good solvent for chiral chromatography, as it is non-polar and does not interfere with the interactions between the enantiomers and the material. However, n-heptane alone is not enough to separate the enantiomers, as it may not have enough eluting power, which is the ability to push the compounds through the column. Therefore, n-heptane is often mixed with other solvents, such as ethanol or isopropanol, which have more eluting power and can affect the selectivity and resolution of the separation. The choice of the solvent mixture is a key step in chiral analysis, and it depends on the properties of the chiral compound and the column material.

In summary, n-heptane is a pure form of heptane, a common solvent and fuel component. It has a special role in measuring the octane rating of gasoline and in separating chiral compounds. n-Heptane is an example of how a simple molecule can have important applications in chemistry and beyond.

n-Pentane is a simple organic compound that belongs to the family of alkanes. It has the chemical formula C5H12 and consists of five carbon atoms linked by single bonds, with each carbon atom attached to three hydrogen atoms. n-Pentane is one of the three isomers of pentane, which means that it has the same molecular formula but a different structure. The other two isomers are isopentane and neopentane, which have more branched structures.

n-Pentane is a colorless liquid at room temperature and pressure, with a characteristic odor of gasoline. It is highly flammable and volatile, meaning that it can easily catch fire and evaporate. It is also insoluble in water, but soluble in most organic solvents. n-Pentane has a boiling point of 36°C and a melting point of -130°C, making it one of the lowest boiling and melting alkanes.

n-Pentane is mainly used as a solvent, a fuel, and a chemical intermediate. As a solvent, it can dissolve various substances such as oils, fats, waxes, resins, and rubber. As a fuel, it can be blended with gasoline to increase its octane rating and reduce its emissions. As a chemical intermediate, it can be converted into other useful compounds such as isoprene, which is used to make synthetic rubber.

n-Pentane is also important for the production of refrigerants, which are substances that can absorb and release heat in cooling systems. n-Pentane is used to make hydrofluorocarbons (HFCs), which are a type of refrigerant that have low ozone depletion potential and global warming potential. HFCs are widely used in air conditioners, refrigerators, and heat pumps.

n-Pentane is a common and versatile compound that has many applications in various industries. However, it also poses some risks to human health and the environment. Exposure to high levels of n-Pentane can cause irritation, drowsiness, headache, nausea, and loss of coordination. Inhalation of n-Pentane can also affect the nervous system and the lungs. n-Pentane can also contribute to air pollution and smog formation when it reacts with oxygen and nitrogen oxides in the presence of sunlight.

Therefore, it is important to handle n-Pentane with care and follow the safety precautions. n-Pentane should be stored in a cool, dry, and well-ventilated place, away from heat, sparks, and flames. n-Pentane should also be disposed of properly and not released into the environment. n-Pentane is a useful but hazardous substance that requires careful management and regulation.

Abstract: Hexane solvents are a family of C6 alkanes that include seven isomers of hexane. They have different boiling points and properties, and can be mixed to form narrow-boiling-range solvents that are suitable for low-temperature oil extraction. This article introduces the advantages of using hexane solvents over conventional solvents, such as energy saving, quality improvement, environmental protection, and safety enhancement. It also discusses the regulatory and technical issues of using hexane solvents, and provides some examples of their industrial applications.

Keywords: hexane solvents; oil extraction; low-temperature; narrow-boiling-range

Article:

Oil extraction is a process of separating oil from oil-bearing materials, such as soybean, rapeseed, peanut, corn germ, and various special oils. It is an important step in the production of edible oil and feed protein. The most common method of oil extraction is solvent extraction, which uses organic solvents to dissolve the oil and separate it from the solid residue.

The choice of solvent is crucial for the efficiency and quality of oil extraction. The solvent should have a high solubility for oil, a low boiling point for easy recovery, a low toxicity for safety and environmental protection, and a low cost for economic feasibility. Among various solvents, hexane is the most widely used one in the oil industry, because it meets most of the requirements. However, hexane is not a single compound, but a mixture of different isomers of C6 alkanes, which have different boiling points and properties.

According to the article by the user, hexane solvents can be classified into seven types, based on their boiling points: cyclohexane (80.74°C), methylcyclopentane (71.81°C), n-hexane (68.74°C), 3-methylpentane (63.28°C), 2-methylpentane (60.27°C), 2,3-dimethylbutane (57.99°C), and 2,2-dimethylbutane (49.72°C). Among them, 3-methylpentane and 2-methylpentane have the closest boiling points to n-hexane, which is the main component of commercial hexane solvents. By mixing 3-methylpentane and 2-methylpentane in appropriate proportions, a narrow-boiling-range hexane solvent can be obtained, which has a boiling range of 61-63°C and a dry point about 5°C lower than n-hexane solvent. This hexane solvent can be used as a low-temperature oil extraction solvent, especially for soybean oil extraction.

The advantages of using hexane solvents over conventional solvents are manifold. First, hexane solvents can reduce the solvent consumption and energy consumption, because they have a narrower boiling range and a lower dry point, which means less solvent is needed to dissolve the same amount of oil, and less heat is needed to recover the solvent from the oil. According to the article, the solvent consumption can be reduced from 1.2-2.0 kg/ton to 0.5-1.2 kg/ton by using narrow-boiling-range solvents. Second, hexane solvents can improve the quality and yield of oil and meal, because they have a lower temperature and a higher selectivity, which means less damage to the oil and protein, and less impurities in the oil and meal. According to the article, the oil yield can be increased by 0.5-1.0%, and the protein content of the meal can be increased by 0.5-1.5% by using low-temperature solvents. Third, hexane solvents can protect the environment and enhance the safety, because they have a lower toxicity and a lower volatility, which means less pollution to the air, water, and soil, and less risk of fire and explosion. According to the article, the hexane solvents belong to C6 alkanes, which are in accordance with the national standards of food additives, plant oil extraction solvents, and industrial hexane, and do not pose any regulatory problems.

The article also provides some examples of the industrial applications of hexane solvents, such as the extraction of soybean, rapeseed, peanut, corn germ, and other bulk oils, as well as the extraction of microbial oils, fish oils, and other heat-sensitive special oils. It claims that some domestic enterprises have developed and applied hexane solvents in dozens of oil extraction plants, and achieved remarkable results in terms of energy saving, quality improvement, environmental protection, and safety enhancement. It also suggests that hexane solvents have the potential to replace the No. 6 solvent and commercial n-hexane as the new choice for oil extraction.

In conclusion, hexane solvents are a family of C6 alkanes that can be mixed to form narrow-boiling-range solvents that are suitable for low-temperature oil extraction. They have many advantages over conventional solvents, such as energy saving, quality improvement, environmental protection, and safety enhancement. They also comply with the national standards and do not require any modification of the existing oil extraction equipment. They can be widely used in the production of various oils, especially soybean oil, and have a bright prospect in the oil industry.

Abstract

Refrigerators use blowing agents to create foam insulation that keeps the cold air inside. Traditionally, chlorofluorocarbons (CFCs) were used as blowing agents, but they were banned due to their harmful effects on the ozone layer. Nowadays, hydrocarbons such as cyclopentane and cyclo/iso-pentane are widely used as alternatives. However, these two blowing agents have different physical and chemical properties that affect their performance and environmental impact. This article compares the advantages and disadvantages of cyclopentane and cyclo/iso-pentane as blowing agents for refrigerators, and provides some suggestions for choosing the best option.

Keywords

blowing agents, refrigerators, cyclopentane, cyclo/iso-pentane, foam insulation, energy efficiency, environmental impact

Introduction

Refrigerators are essential appliances that help us preserve food and beverages at low temperatures. To achieve this, refrigerators need to have a good insulation system that prevents heat transfer from the outside to the inside. One of the most common insulation materials used in refrigerators is polyurethane foam, which is formed by a chemical reaction between polyether polyol and isocyanate. The reaction releases heat, which is used to vaporize a blowing agent that expands the foam and creates air pockets. The air pockets act as thermal barriers that reduce heat conduction and convection.

However, not all blowing agents are equally effective and eco-friendly. Some of them, such as CFCs, have high ozone depletion potential (ODP) and global warming potential (GWP), meaning that they can damage the ozone layer and contribute to climate change. Therefore, CFCs were phased out by the Montreal Protocol in 1987, and replaced by other substances that have lower ODP and GWP. Among these alternatives, hydrocarbons such as cyclopentane and cyclo/iso-pentane have gained popularity due to their low cost, availability, and flammability.

Cyclopentane and cyclo/iso-pentane are both five-carbon ring compounds, but they have different molecular structures. Cyclopentane has a regular pentagon shape, while cyclo/iso-pentane has a branch attached to one of the carbon atoms. This difference leads to different physical and chemical properties, such as boiling point, vapor pressure, vapor thermal conductivity, and solubility. These properties affect the foam formation, insulation performance, energy efficiency, and environmental impact of the blowing agents. Therefore, it is important to understand the advantages and disadvantages of cyclopentane and cyclo/iso-pentane as blowing agents for refrigerators, and to choose the best option according to the specific needs and conditions.

Comparison of Cyclopentane and Cyclo/Iso-Pentane

Boiling Point

The boiling point of a substance is the temperature at which it changes from liquid to gas. The boiling point of cyclopentane is 49°C, while the boiling point of cyclo/iso-pentane is 28°C. This means that cyclo/iso-pentane vaporizes more easily than cyclopentane, and therefore requires less heat to create foam. This can be an advantage for cyclo/iso-pentane, as it can reduce the energy consumption and the reaction time of the foam formation process. However, it can also be a disadvantage, as it can cause more blowing agent to escape from the foam, reducing the insulation quality and increasing the environmental impact.

Vapor Pressure

The vapor pressure of a substance is the pressure exerted by its vapor when it is in equilibrium with its liquid phase. The vapor pressure of cyclo/iso-pentane is higher than that of cyclopentane, especially at low temperatures. This means that cyclo/iso-pentane can maintain a gaseous state inside the foam even at low temperatures, and therefore provide some support to the foam structure. This can improve the dimensional stability of the foam, and prevent shrinkage and deformation. However, it can also increase the risk of leakage and flammability of the blowing agent, as well as the heat transfer through the foam.

Vapor Thermal Conductivity

The vapor thermal conductivity of a substance is the measure of its ability to transfer heat by molecular motion. The vapor thermal conductivity of cyclo/iso-pentane is higher than that of cyclopentane, especially at high temperatures. This means that cyclo/iso-pentane can conduct more heat through the foam than cyclopentane, and therefore reduce the insulation performance and the energy efficiency of the refrigerator. However, this effect can be mitigated by using a lower density of foam, as well as by adding other additives or fillers to the foam.

Solubility

The solubility of a substance is the measure of its ability to dissolve in another substance. The solubility of cyclo/iso-pentane in polyether polyol is lower than that of cyclopentane, especially at high temperatures. This means that cyclo/iso-pentane can separate from the polyol more easily than cyclopentane, and therefore create a more uniform distribution of blowing agent in the foam. This can enhance the foam quality and the insulation performance, as well as reduce the amount of blowing agent needed. However, this can also increase the difficulty of controlling the foam formation process, as well as the risk of flammability and environmental impact of the blowing agent.

Conclusion

Cyclopentane and cyclo/iso-pentane are both hydrocarbon blowing agents that can be used to create foam insulation for refrigerators. However, they have different physical and chemical properties that affect their performance and environmental impact. Cyclopentane has a higher boiling point, lower vapor pressure, lower vapor thermal conductivity, and higher solubility than cyclo/iso-pentane. These properties make cyclopentane more suitable for applications that require high insulation performance, low energy consumption, and low environmental impact. Cyclo/iso-pentane has a lower boiling point, higher vapor pressure, higher vapor thermal conductivity, and lower solubility than cyclopentane. These properties make cyclo/iso-pentane more suitable for applications that require low foam density, high dimensional stability, and fast foam formation. Therefore, the choice of blowing agent depends on the specific needs and conditions of the refrigerator manufacturer and the consumer. A possible compromise is to use a mixture of cyclopentane and cyclo/iso-pentane, which can combine the advantages of both blowing agents and balance their disadvantages.

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