PETROLEUM

Composition of petroleum In its strictest sense, petroleum includes only crude oil, but in common usage it includes all liquid, gaseous, and solid (e.g., paraffin) hydrocarbons. Under surface pressure and temperature conditions, lighter hydrocarbons methane, ethane, propane and butane occur as gases, while pentane and heavier ones are in the form of liquids or solids. However, in an underground oil reservoir the proportions of gas, liquid, and solid depend on subsurface conditions and on the phase diagram of the petroleum mixture.[9] An oil well produces predominantly crude oil, with some natural gas dissolved in it. Because the pressure is lower at the surface than underground, some of the gas will come out of solution and be recovered (or burned) as associated gas or solution gas. A gas well produces predominantly natural gas. However, because the underground temperature and pressure are higher than at the surface, the gas may contain heavier hydrocarbons such as pentane, hexane, and heptane in the gaseous state. At surface conditions these will condense out of the gas to form natural gas condensate, often shortened to condensate. Condensate resembles petrol in appearance and is similar in composition to some volatile light crude oils. The proportion of light hydrocarbons in the petroleum mixture varies greatly among different oil fields, ranging from as much as 97 per cent by weight in the lighter oils to as little as 50 per cent in the heavier oils and bitumens. The hydrocarbons in crude oil are mostly alkanes, cycloalkanes and various aromatic hydrocarbons while the other organic compounds contain nitrogen, oxygen and sulfur, and trace amounts of metals such as iron, nickel, copper and vanadium. The exact molecular composition varies widely from formation to formation but the proportion of chemical elements vary over fairly narrow limits as follows:[10] Composition by weight Element Percent range Carbon 83 to 87% Hydrogen 10 to 14% Nitrogen 0.1 to 2% Oxygen 0.05 to 1.5% Sulfur 0.05 to 6.0% Metals < 0.1% Four different types of hydrocarbon molecules appear in crude oil. The relative percentage of each varies from oil to oil, determining the properties of each oil.[9] Composition by weight Hydrocarbon Average Range Paraffins 30% 15 to 60% Naphthenes 49% 30 to 60% Aromatics 15% 3 to 30% Asphaltics 6% remainder Most of the world's oils are non-conventional.[11] Crude oil varies greatly in appearance depending on its composition. It is usually black or dark brown (although it may be yellowish, reddish, or even greenish). In the reservoir it is usually found in association with natural gas, which being lighter forms a gas cap over the petroleum, and saline water which, being heavier than most forms of crude oil, generally sinks beneath it. Crude oil may also be found in semi-solid form mixed with sand and water, as in the Athabasca oil sands in Canada, where it is usually referred to as crude bitumen. In Canada, bitumen is considered a sticky, black, tar-like form of crude oil which is so thick and heavy that it must be heated or diluted before it will flow.[12] Venezuela also has large amounts of oil in the Orinoco oil sands, although the hydrocarbons trapped in them are more fluid than in Canada and are usually called extra heavy oil. These oil sands resources are called unconventional oil to distinguish them from oil which can be extracted using traditional oil well methods. Between them, Canada and Venezuela contain an estimated 3.6 trillion barrels (570×109 m3) of bitumen and extra-heavy oil, about twice the volume of the world's reserves of conventional oil.[13] Petroleum is used mostly, by volume, for producing fuel oil and petrol, both important "primary energy" sources.[14] 84 per cent by volume of the hydrocarbons present in petroleum is converted into energy-rich fuels (petroleum-based fuels), including petrol, diesel, jet, heating, and other fuel oils, and liquefied petroleum gas.[15] The lighter grades of crude oil produce the best yields of these products, but as the world's reserves of light and medium oil are depleted, oil refineries are increasingly having to process heavy oil and bitumen, and use more complex and expensive methods to produce the products required. Because heavier crude oils have too much carbon and not enough hydrogen, these processes generally involve removing carbon from or adding hydrogen to the molecules, and using fluid catalytic cracking to convert the longer, more complex molecules in the oil to the shorter, simpler ones in the fuels. Due to its high energy density, easy transportability and relative abundance, oil has become the world's most important source of energy since the mid-1950s. Petroleum is also the raw material for many chemical products, including pharmaceuticals, solvents, fertilizers, pesticides, and plastics; the 16 per cent not used for energy production is converted into these other materials. Petroleum is found in porous rock formations in the upper strata of some areas of the Earth's crust. There is also petroleum in oil sands (tar sands). Known oil reserves are typically estimated at around 190 km3 (1.2 trillion (short scale) barrels) without oil sands[16], or 595 km3 (3.74 trillion barrels) with oil sands.[17] Consumption is currently around 84 million barrels (13.4×106 m3) per day, or 4.9 km3 per year. Which in turn yields a remaining oil supply of only about 120 years, if current demand remain static.

Why Ethylene Can Make A Fast Fruit Ripe?

To discuss how it works, we should mention that there are two types of fruit: climacteric and non-climacteric. Climacteric fruits continue ripening after being picked (which will be accelerated by ethylene gas). Climacteric fruits include: apples, apricots, avocados, bananas, cantaloupes, figs, guava, kiwis, mangoes, nectarines, peaches, pears, plums, and tomatoes. Non-climacteric fruits ripen only while still attached to the plant. Their shelf life is diminished if harvested at peak ripeness. Non-climacteric fruits include: cherries, grapes, limes, oranges, pineapples, and berries (blue-, black-, rasp-, straw-, etc.). Essentially all parts of higher plants produce ethylene (stems, roots, flowers, tubers, and seedlings). Ethylene production is induced at several key stages of the plant’s life. Notable for us, ethylene production is promoted during fruit ripening and abscission (dropping) of leaves. However, it is now known that ethylene production can be artificially increased by external factors: wounding of the fruit, environmental stress, and exposure to certain chemicals. The biosynthesis of ethylene starts with the amino acid methionine. The enzyme met adenosyltransferase converts methionine into S-adenosyl-L-methionine (SAM). The enzyme ACC synthase (ACS) converts SAM into 1-aminocyclopropane-1-carboxylate (ACC). The last step in ethylene biosynthesis involves molecular oxygen. The enzyme ACC-oxidase (ACO, which used to be called Ethylene Forming Enzyme, EFE) converts ACC into ethylene, as well as carbon dioxide, hydrogen cyanide, and water. Ethylene Biosynthesis Ethylene Biosynthesis The rate of ethylene production is regulated by ACC synthase converting SAM into ACC. Thus, regulation of this enzyme is key for the biosynthesis of ethylene. Manipulation of this enzyme by biotechnology delays fruit ripening. The Flavr Savr tomatoes used this biotechnology. On the other hand, in a sort of positive feedback loop, the biosynthesis of ethylene is upregulated by either endogenous or exogenous ethylene. Producing ethylene causes more ethylene to be produced. In 1993, the genes involved in the fruit ripening response were identified. The ETR1 and CTR1 genes are turned on until ethylene is produced. Then ETR1 and CTR1 turn off. This initiates a cascade ultimately turning other genes on. These other genes make the various enzymes mentioned earlier (amylases, hydrolases, kinases, and pectinases) needed to ripen the fruit. ince ethylene controls the ripening process, if we can control the ethylene, we can control the fruit. While ethylene is synthesized by plants, it is also prepared commercially. Ethylene is the most produced organic compound in the world (>107 million metric tons in 2005). The petrochemical industry produces ethylene through steam cracking of gaseous or light liquid hydrocarbons by heating to 750-950 °C. Compression and distillation purifies the ethylene. Ethylene is then used for a variety of applications, including the synthesis of PVC and polyethylene plastics. The picking of unripe fruit and artificial ripening later is not uncommon. In parts of Asia, a plastic cover is placed over unripe harvested mangoes. Calcium carbide is placed in open containers in strategic positions inside the bag. Moisture from the air converts the calcium carbide into acetylene which has the same fruit-ripening effect as ethylene. However, industrial-grade calcium carbide is sometimes contaminated with trace arsenic and phosphorous. The use of calcium carbide to stimulate fruit ripening is illegal in most countries. Catalytic Ethylene Generator An ethylene generator More commonly, however, catalytic generators are used to produce the ethylene gas necessary for fruit ripening. The generators allow for control of the overall ethylene concentration in the room. Typically, between 500-2000 ppm of ethylene is administered for 24-48 hours to successfully ripen the fruit. On the other side of the spectrum, after the unripe fruit is picked, we want it to remain unripe until after shipment. Scientists have researched ways to inhibit ethylene biosynthesis and inhibit ethylene perception. Aminoethoxyvinylglycine (AVG), aminooxyacetic acid (AOA), and silver ions inhibit ethylene synthesis, but this is not always effective because exogenous ethylene can still be perceived by the fruit and stimulate ripening. 1-methylcyclopropene 1-MCP

Ethylene based low cost ripening process

alkane

Straight Chain Alkanes The general formula for an alkane is CnH2n+2 where n is the number of carbon atoms in the molecule. There are two ways of writing a condensed structural formula. For example, butane may be written as CH3CH2CH2CH3 or CH3(CH2)2CH3. Rules for Naming Alkanes * The parent name of the molecule is determined by the number of carbons in the longest chain. * In the case where two chains have the same number of carbons, the parent is the chain with the most substituents. * The carbons in the chain are numbered starting from the end nearest the first substituent. * In the case where there are substituents having the same number of carbons from both ends, numbering starts from the end nearest the next substituent. * When more than one of a given substituent is present, a prefix is applied to indicate the number of substituents. Use di- for two, tri- for three, tetra- for four, etc. and use the number assigned to the carbon to indicate the position of each substituent. Branched Alkanes * Branched substituents are numbered starting from the carbon of the substituent attached to the parent chain. From this carbon, count the number of carbons in the longest chain of the substituent. The substituent is named as an alkyl group based on the number of carbons in this chain. * Numbering of the substituent chain starts from the carbon attached to the parent chain. * The entire name of the branched substituent is placed in parentheses, preceded by a number indicating which parent-chain carbon it joins. * Substituents are listed in alphabetical order. To alphabetize, ignore numerical (di-, tri-, tetra-) prefixes (e.g., ethyl would come before dimethyl), but don't ignore don't ignore positional prefixes such as iso and tert (e.g., triethyl comes before tertbutyl). Cyclic Alkanes * The parent name is determined by the number of carbons in the largest ring (e.g., cycloalkane such as cyclohexane). * In the case where the ring is attached to a chain containing additional carbons, the ring is considered to be a substituent on the chain. A substituted ring that is a substituent on something else is named using the rules for branched alkanes. * When two rings are attached to each other, the larger ring is the parent and the smaller is a cycloalkyl substituent. * The carbons of the ring are numbered such that the substituents are given the lowest possible numbers. Straight Chain Alkanes # Carbon Name Molecular Formula Structural Formula 1 Methane CH4 CH4 2 Ethane C2H6 CH3CH3 3 Propane C3H8 CH3CH2CH3 4 Butane C4H10 CH3CH2CH2CH3 5 Pentane C5H12 CH3CH2CH2CH2CH3 6 Hexane C6H14 CH3(CH2)4CH3 7 Heptane C7H16 CH3(CH2)5CH3 8 Octane C8H18 CH3(CH2)6CH3 9 Nonane C9H20 CH3(CH2)7CH3 10 Decane C10H22 CH3(CH2)8CH3

hydrocarbon

a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon.[1] Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls.[2] Aromatic hydrocarbons (arenes), alkanes, alkenes, cycloalkanes and alkyne-based compounds are different types of hydrocarbons. he classifications for hydrocarbons defined by IUPAC nomenclature of organic chemistry are as follows: 1. Saturated hydrocarbons (alkanes) are the simplest of the hydrocarbon species and are composed entirely of single bonds and are saturated with hydrogen. The general formula for saturated hydrocarbons is CnH2n+2 (assuming non-cyclic structures).[5] Saturated hydrocarbons are the basis of petroleum fuels and are found as either linear or branched species. Hydrocarbons with the same molecular formula but different structural formulae are called structural isomers.[6] As given in the example of 3-methylhexane and its higher homologues, branched hydrocarbons can be chiral.[7] Chiral saturated hydrocarbons constitute the side chains of biomolecules such as chlorophyll and tocopherol.[8] 2. Unsaturated hydrocarbons have one or more double or triple bonds between carbon atoms. Those with double bond are called alkenes. Those with one double bond have the formula CnH2n (assuming non-cyclic structures).[9] Those containing triple bonds are called alkynes, with general formula CnH2n-2.[10] 3. Cycloalkanes are hydrocarbons containing one or more carbon rings to which hydrogen atoms are attached. The general formula for a saturated hydrocarbon containing one ring is CnH2n.[6] 4. Aromatic hydrocarbons, also known as arenes, are hydrocarbons that have at least one aromatic ring.

how do the prefixes and suffixes for the open chain hydrocarbons indicate formula: methane,ethane,propane,?

video of organic chemistry