In organic chemistry, an alkene is an unsaturated hydrocarbon that contains at least one carbon–carbon double bond. The words alkene and olefin are used interchangeably. Acyclic alkenes, with only one double bond and no other functional groups, known as mono-enes, form a homologous series of hydrocarbons with the general formula CnH2n. Alkenes have two hydrogen atoms fewer than the corresponding alkane; the simplest alkene, with the International Union of Pure and Applied Chemistry name ethene, is the organic compound produced on the largest scale industrially. Aromatic compounds are drawn as cyclic alkenes, but their structure and properties are different and they are not considered to be alkenes. Like a single covalent bond, double bonds can be described in terms of overlapping atomic orbitals, except that, unlike a single bond, a carbon–carbon double bond consists of one sigma bond and one pi bond; this double bond is stronger than a single covalent bond and shorter, with an average bond length of 1.33 ångströms.
Each carbon of the double bond uses its three sp2 hybrid orbitals to form sigma bonds to three atoms. The unhybridized 2p atomic orbitals, which lie perpendicular to the plane created by the axes of the three sp² hybrid orbitals, combine to form the pi bond; this bond lies outside the main C–C axis, with half of the bond on one side of the molecule and half on the other. With a strength of 65 kcal/mol, the pi bond is weaker than the sigma bond. Rotation about the carbon–carbon double bond is restricted because it incurs an energetic cost to break the alignment of the p orbitals on the two carbon atoms; as a consequence, substituted alkenes may exist as one of called cis or trans isomers. More complex alkenes may be named with the E–Z notation for molecules with three or four different substituents. For example, of the isomers of butene, the two methyl groups of -but-2-ene appear on the same side of the double bond, in -but-2-ene the methyl groups appear on opposite sides; these two isomers of butene are different in their chemical and physical properties.
Twisting to a 90° dihedral angle between two of the groups on the carbons requires less energy than the strength of a pi bond, the bond still holds. The carbons of the double bond become pyramidal, which allows preserving some p orbital alignment—and hence pi bonding; the other two attached. This contradicts a common textbook assertion that the two carbons retain their planar nature when twisting, in which case the p orbitals would rotate enough away from each other to be unable to sustain a pi bond. In a 90°-twisted alkene, the p orbitals are only misaligned by 42° and the strain energy is only around 40 kcal/mol. In contrast, a broken pi bond has an energetic cost of around 65 kcal/mol; some pyramidal alkenes are stable. For example, trans-cyclooctene is a stable strained alkene and the orbital misalignment is only 19°, despite having a significant dihedral angle of 137° and a degree of pyramidalization of 18°. Trans-cycloheptene is stable at low temperatures; as predicted by the VSEPR model of electron pair repulsion, the molecular geometry of alkenes includes bond angles about each carbon in a double bond of about 120°.
The angle may vary because of steric strain introduced by nonbonded interactions between functional groups attached to the carbons of the double bond. For example, the C–C–C bond angle in propylene is 123.9°. For bridged alkenes, Bredt's rule states that a double bond cannot occur at the bridgehead of a bridged ring system unless the rings are large enough. Following Fawcett and defining S as the total number of non-bridgehead atoms in the rings, bicyclic systems require S ≥ 7 for stability and tricyclic systems require S ≥ 11. Many of the physical properties of alkenes and alkanes are similar: they are colourless and combustable; the physical state depends on molecular mass: like the corresponding saturated hydrocarbons, the simplest alkenes, ethene and butene are gases at room temperature. Linear alkenes of five to sixteen carbons are liquids, higher alkenes are waxy solids; the melting point of the solids increases with increase in molecular mass. Alkenes have stronger smells than the corresponding alkane.
Ethylene is described to have a "sweet" odor, for example. The binding of cupric ion to the olefin in the mammalian olfactory receptor MOR244-3 is implicated in the smell of alkenes. Strained alkenes, in particular, like norbornene and trans-cyclooctene are known to have strong, unpleasant odors, a fact consistent with the stronger π complexes they form with metal ions including copper. Alkenes are stable compounds, but are more reactive than alkanes, either because of the reactivity of the carbon–carbon pi-bond or the presence of allylic CH centers. Most reactions of alkenes involve additions to this pi bond. Alkenes serve as a feedstock for the petrochemical industry because they can participate in a wide variety of reactions, prominently polymerization and alkylation. Alkenes react in many addition reactions. Most of these addition reactions follow the mechanism of electrophilic addition. Examples are hydrohalogenation, halohydrin formation, hydroboration, dichlorocarbene addition, Simmons–Smith reaction, catalytic hydrogenation, epox
A solvent is a substance that dissolves a solute, resulting in a solution. A solvent is a liquid but can be a solid, a gas, or a supercritical fluid; the quantity of solute that can dissolve in a specific volume of solvent varies with temperature. Common uses for organic solvents are in dry cleaning, as paint thinners, as nail polish removers and glue solvents, in spot removers, in detergents and in perfumes. Water is a solvent for the most common solvent used by living things. Solvents find various applications in chemical, pharmaceutical and gas industries, including in chemical syntheses and purification processes; when one substance is dissolved into another, a solution is formed. This is opposed to the situation. In a solution, all of the ingredients are uniformly distributed at a molecular level and no residue remains. A solvent-solute mixture consists of a single phase with all solute molecules occurring as solvates, as opposed to separate continuous phases as in suspensions and other types of non-solution mixtures.
The ability of one compound to be dissolved in another is known as solubility. In addition to mixing, the substances in a solution interact with each other at the molecular level; when something is dissolved, molecules of the solvent arrange around molecules of the solute. Heat transfer is involved and entropy is increased making the solution more thermodynamically stable than the solute and solvent separately; this arrangement is mediated by the respective chemical properties of the solvent and solute, such as hydrogen bonding, dipole moment and polarizability. Solvation does not cause a chemical chemical configuration changes in the solute. However, solvation resembles a coordination complex formation reaction with considerable energetics and is thus far from a neutral process. Solvents can be broadly classified into two categories: non-polar. A special case is mercury; the dielectric constant of the solvent provides a rough measure of a solvent's polarity. The strong polarity of water is indicated by its high dielectric constant of 88.
Solvents with a dielectric constant of less than 15 are considered to be nonpolar. The dielectric constant measures the solvent's tendency to cancel the field strength of the electric field of a charged particle immersed in it; this reduction is compared to the field strength of the charged particle in a vacuum. Heuristically, the dielectric constant of a solvent can be thought of as its ability to reduce the solute's effective internal charge; the dielectric constant of a solvent is an acceptable predictor of the solvent's ability to dissolve common ionic compounds, such as salts. Dielectric constants are not the only measure of polarity; because solvents are used by chemists to carry out chemical reactions or observe chemical and biological phenomena, more specific measures of polarity are required. Most of these measures are sensitive to chemical structure; the Grunwald–Winstein mY scale measures polarity in terms of solvent influence on buildup of positive charge of a solute during a chemical reaction.
Kosower's Z scale measures polarity in terms of the influence of the solvent on UV-absorption maxima of a salt pyridinium iodide or the pyridinium zwitterion. Donor number and donor acceptor scale measures polarity in terms of how a solvent interacts with specific substances, like a strong Lewis acid or a strong Lewis base; the Hildebrand parameter is the square root of cohesive energy density. It can not accommodate complex chemistry. Reichardt's dye, a solvatochromic dye that changes color in response to polarity, gives a scale of ET values. ET is the transition energy between the ground state and the lowest excited state in kcal/mol, identifies the dye. Another correlated scale can be defined with Nile red; the polarity, dipole moment and hydrogen bonding of a solvent determines what type of compounds it is able to dissolve and with what other solvents or liquid compounds it is miscible. Polar solvents dissolve polar compounds best and non-polar solvents dissolve non-polar compounds best: "like dissolves like".
Polar compounds like sugars or ionic compounds, like inorganic salts dissolve only in polar solvents like water, while non-polar compounds like oils or waxes dissolve only in non-polar organic solvents like hexane. Water and hexane are not miscible with each other and will separate into two layers after being shaken well. Polarity can be separated to different contributions. For example, the Kamlet-Taft parameters are dipolarity/polarizability, hydrogen-bonding acidity and hydrogen-bonding basicity; these can be calculated from the wavelength shifts of 3–6 different solvatochromic dyes in the solvent including Reichardt's dye and diethylnitroaniline. Another option, Hansen's parameters, separate the cohesive energy density into dispersion and hydrogen bonding contributions. Solvents with a dielectric constant (more relative
The chemical industry comprises the companies that produce industrial chemicals. Central to the modern world economy, it converts raw materials into more than 70,000 different products; the plastics industry contains some overlap, as most chemical companies produce plastic as well as other chemicals. Various professionals are involved in the chemical industry including chemical engineers, lab chemists, etc; as of 2018, the chemical industry comprises 15% of the US manufacturing economic sector. Although chemicals were made and used throughout history, the birth of the heavy chemical industry coincided with the beginnings of the Industrial Revolution in general. One of the first chemicals to be produced in large amounts through industrial processes was sulfuric acid. In 1736, the pharmacist Joshua Ward developed a process for its production that involved heating saltpeter, allowing the sulfur to oxidize and combine with water, it was the first practical production of sulphuric acid on a large scale.
John Roebuck and Samuel Garbett were the first to establish a large-scale factory in Prestonpans, Scotland, in 1749, which used leaden condensing chambers for the manufacture of sulfuric acid. In the early 18th century, cloth was bleached by treating it with stale urine or sour milk and exposing it to sunlight for long periods of time, which created a severe bottleneck in production. Sulfuric acid began to be used as a more efficient agent as well as lime by the middle of the century, but it was the discovery of bleaching powder by Charles Tennant that spurred the creation of the first great chemical industrial enterprise, his powder was made by reacting chlorine with dry slaked lime and proved to be a cheap and successful product. He opened a factory in St Rollox, north of Glasgow, production went from just 52 tons in 1799 to 10,000 tons just five years later. Soda ash was used since ancient times in the production of glass, textile and paper, the source of the potash had traditionally been wood ashes in Western Europe.
By the 18th century, this source was becoming uneconomical due to deforestation, the French Academy of Sciences offered a prize of 2400 livres for a method to produce alkali from sea salt. The Leblanc process was patented in 1791 by Nicolas Leblanc who built a Leblanc plant at Saint-Denis, he was denied his prize money because of the French Revolution. However, it was in Britain that the Leblanc process took off. William Losh built the first soda works in Britain at the Losh and Bell works on the River Tyne in 1816, but it remained on a small scale due to large tariffs on salt production until 1824; when these tariffs were repealed, the British soda industry was able to expand. James Muspratt's chemical works in Liverpool and Charles Tennant's complex near Glasgow became the largest chemical production centres anywhere. By the 1870s, the British soda output of 200,000 tons annually exceeded that of all other nations in the world combined; these huge factories began to produce a greater diversity of chemicals as the Industrial Revolution matured.
Large quantities of alkaline waste were vented into the environment from the production of soda, provoking one of the first pieces of environmental legislation to be passed in 1863. This provided for close inspection of the factories and imposed heavy fines on those exceeding the limits on pollution. Methods were soon devised to make useful byproducts from the alkali; the Solvay process was developed by the Belgian industrial chemist Ernest Solvay in 1861. In 1864, Solvay and his brother Alfred constructed a plant in the Belgian town of Charleroi and in 1874, they expanded into a larger plant in Nancy, France; the new process proved more economical and less polluting than the Leblanc method, its use spread. In the same year, Ludwig Mond visited Solvay to acquire the rights to use his process, he and John Brunner formed the firm of Brunner, Mond & Co. and built a Solvay plant at Winnington, England. Mond was instrumental in making the Solvay process a commercial success; the late 19th century saw an explosion in both the quantity of production and the variety of chemicals that were manufactured.
Large chemical industries took shape in Germany and in the United States. Production of artificial manufactured fertilizer for agriculture was pioneered by Sir John Lawes at his purpose-built Rothamsted Research facility. In the 1840s he established large works near London for the manufacture of superphosphate of lime. Processes for the vulcanization of rubber were patented by Charles Goodyear in the United States and Thomas Hancock in England in the 1840s; the first synthetic dye was discovered by William Henry Perkin in London. He transformed aniline into a crude mixture which, when extracted with alcohol, produced a substance with an intense purple colour, he developed the first synthetic perfumes. However, it was German industry that began to dominate the field of synthetic dyes; the three major firms BASF, Bayer and Hoechst produced several hundred different dyes, by 1913, the German industry produced 90 percent of the world supply of dyestuffs and sold about 80 percent of their production abroad.
In the United States, Herbert Henry Dow's use of electrochemistry to produce chemicals from brine was a commercial success that helped to promote the country's chemical industry. The petrochemical industry can be traced back to the oil works of James Young in Scotland and Abraham Pineo Gesne
Maize known as corn, is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The leafy stalk of the plant produces pollen inflorescences and separate ovuliferous inflorescences called ears that yield kernels or seeds, which are fruits. Maize has become a staple food in many parts of the world, with the total production of maize surpassing that of wheat or rice. However, little of this maize is consumed directly by humans: most is used for corn ethanol, animal feed and other maize products, such as corn starch and corn syrup; the six major types of maize are dent corn, flint corn, pod corn, flour corn, sweet corn. Maize is the most grown grain crop throughout the Americas, with 361 million metric tons grown in the United States in 2014. 40% of the crop—130 million tons—is used for corn ethanol. Genetically modified maize made up 85% of the maize planted in the United States in 2009. Sugar-rich varieties called sweet corn are grown for human consumption as kernels, while field corn varieties are used for animal feed, various corn-based human food uses, as chemical feedstocks.
Maize is used in making ethanol and other biofuels. Most historians believe. Recent research in the early 21st century has modified this view somewhat. An influential 2002 study by Matsuoka et al. has demonstrated that, rather than the multiple independent domestications model, all maize arose from a single domestication in southern Mexico about 9,000 years ago. The study demonstrated that the oldest surviving maize types are those of the Mexican highlands. Maize spread from this region over the Americas along two major paths; this is consistent with a model based on the archaeological record suggesting that maize diversified in the highlands of Mexico before spreading to the lowlands. Archaeologist Dolores Piperno has said: A large corpus of data indicates that it was dispersed into lower Central America by 7600 BP and had moved into the inter-Andean valleys of Colombia between 7000 and 6000 BP. Since even earlier dates have been published. According to a genetic study by Embrapa, corn cultivation was introduced in South America from Mexico, in two great waves: the first, more than 6000 years ago, spread through the Andes.
Evidence of cultivation in Peru has been found dating to about 6700 years ago. The second wave, about 2000 years ago, through the lowlands of South America. Before domestication, maize plants grew only small, 25 millimetres long corn cobs, only one per plant. In Spielvogel's view, many centuries of artificial selection by the indigenous people of the Americas resulted in the development of maize plants capable of growing several cobs per plant, which were several centimetres/inches long each; the Olmec and Maya cultivated maize in numerous varieties throughout Mesoamerica. It was believed. Research of the 21st century has established earlier dates; the region developed a trade network based on surplus and varieties of maize crops. Mapuches of south-central Chile cultivated maize along with quinoa and potatoes in Pre-Hispanic times, however potato was the staple food of most Mapuches, "specially in the southern and coastal territories where maize did not reach maturity". Before the expansion of the Inca Empire maize was traded and transported as far south as 40°19' S in Melinquina, Lácar Department.
In that location maize remains were found inside pottery dated to 730 ±80 BP and 920 ±60 BP. This maize was brought across the Andes from Chile; the presence of maize in Guaitecas Archipelago, which constitute southernmost outspost of Pre-Hispanic agriculture, is reported by early Spanish explorers. However the Spanish may have misidentified the plant. After the arrival of Europeans in 1492, Spanish settlers consumed maize and explorers and traders carried it back to Europe and introduced it to other countries. Spanish settlers far preferred wheat bread to cassava, or potatoes. Maize flour could not be substituted for wheat for communion bread, since in Christian belief only wheat could undergo transubstantiation and be transformed into the body of Christ; some Spaniards worried that by eating indigenous foods, which they did not consider nutritious, they would weaken and risk turning into Indians. "In the view of Europeans, it was the food they ate more than the environment in which they lived, that gave Amerindians and Spaniards both their distinctive physical characteristics and their characteristic personalities."
Despite these worries, Spaniards did consume maize. Archeological evidence from Florida sites indicate. Maize spread to the rest of the world because of its ability to grow in diverse climates, it was cultivated in Spain just a few decades after Columbus's voyages and spread to Italy, West Africa and elsewhere. The word maize derives from the Spanish form of the indigenous Taíno word for mahiz, it is known by other names around the world. The word "corn" outside North America and New Zealand refers to any cereal crop, its meaning understood to vary geographically to refer to the local staple. In the United Stat
The United States of America known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U. S. is the third most populous country. The capital is Washington, D. C. and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico; the State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean; the U. S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The diverse geography and wildlife of the United States make it one of the world's 17 megadiverse countries.
Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago. European colonization began in the 16th century; the United States emerged from the thirteen British colonies established along the East Coast. Numerous disputes between Great Britain and the colonies following the French and Indian War led to the American Revolution, which began in 1775, the subsequent Declaration of Independence in 1776; the war ended in 1783 with the United States becoming the first country to gain independence from a European power. The current constitution was adopted in 1788, with the first ten amendments, collectively named the Bill of Rights, being ratified in 1791 to guarantee many fundamental civil liberties; the United States embarked on a vigorous expansion across North America throughout the 19th century, acquiring new territories, displacing Native American tribes, admitting new states until it spanned the continent by 1848. During the second half of the 19th century, the Civil War led to the abolition of slavery.
By the end of the century, the United States had extended into the Pacific Ocean, its economy, driven in large part by the Industrial Revolution, began to soar. The Spanish–American War and World War I confirmed the country's status as a global military power; the United States emerged from World War II as a global superpower, the first country to develop nuclear weapons, the only country to use them in warfare, a permanent member of the United Nations Security Council. Sweeping civil rights legislation, notably the Civil Rights Act of 1964, the Voting Rights Act of 1965 and the Fair Housing Act of 1968, outlawed discrimination based on race or color. During the Cold War, the United States and the Soviet Union competed in the Space Race, culminating with the 1969 U. S. Moon landing; the end of the Cold War and the collapse of the Soviet Union in 1991 left the United States as the world's sole superpower. The United States is the world's oldest surviving federation, it is a representative democracy.
The United States is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States, other international organizations. The United States is a developed country, with the world's largest economy by nominal GDP and second-largest economy by PPP, accounting for a quarter of global GDP; the U. S. economy is post-industrial, characterized by the dominance of services and knowledge-based activities, although the manufacturing sector remains the second-largest in the world. The United States is the world's largest importer and the second largest exporter of goods, by value. Although its population is only 4.3% of the world total, the U. S. holds 31% of the total wealth in the world, the largest share of global wealth concentrated in a single country. Despite wide income and wealth disparities, the United States continues to rank high in measures of socioeconomic performance, including average wage, human development, per capita GDP, worker productivity.
The United States is the foremost military power in the world, making up a third of global military spending, is a leading political and scientific force internationally. In 1507, the German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere America in honor of the Italian explorer and cartographer Amerigo Vespucci; the first documentary evidence of the phrase "United States of America" is from a letter dated January 2, 1776, written by Stephen Moylan, Esq. to George Washington's aide-de-camp and Muster-Master General of the Continental Army, Lt. Col. Joseph Reed. Moylan expressed his wish to go "with full and ample powers from the United States of America to Spain" to seek assistance in the revolutionary war effort; the first known publication of the phrase "United States of America" was in an anonymous essay in The Virginia Gazette newspaper in Williamsburg, Virginia, on April 6, 1776. The second draft of the Articles of Confederation, prepared by John Dickinson and completed by June 17, 1776, at the latest, declared "The name of this Confederation shall be the'United States of America'".
The final version of the Articles sent to the states for ratification in late 1777 contains the sentence "The Stile of this Confederacy shall be'The United States of America'". In June 1776, Thomas Jefferson wrote the phrase "UNITED STATES OF AMERICA" in all capitalized letters in the headline of his "original Rough draught" of the Declaration of Independence; this draft of the document did not surface unti
A fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms, containing energy originating in ancient photosynthesis. The age of the organisms and their resulting fossil fuels is millions of years, sometimes exceeds 650 million years. Fossil fuels contain high percentages of carbon and include petroleum and natural gas. Other used derivatives include kerosene and propane. Fossil fuels range from volatile materials with low carbon to hydrogen ratios like methane, to liquids like petroleum, to nonvolatile materials composed of pure carbon, like anthracite coal. Methane can be found in hydrocarbon fields either alone, associated with oil, or in the form of methane clathrates; the theory that fossil fuels formed from the fossilized remains of dead plants by exposure to heat and pressure in the Earth's crust over millions of years was first introduced by Andreas Libavius "in his 1597 Alchemia " and by Mikhail Lomonosov "as early as 1757 and by 1763".
The first use of the term "fossil fuel" was by the German chemist Caspar Neumann, in English translation in 1759. In 2017 the world's primary energy sources consisted of petroleum, natural gas, amounting to an 85% share for fossil fuels in primary energy consumption in the world. Non-fossil sources in 2006 included nuclear and others amounting to 0.9%. World energy consumption was growing at about 2.3% per year. In 2015 about 18% of worldwide consumption was from renewable sources. Although fossil fuels are continually being formed via natural processes, they are considered to be non-renewable resources because they take millions of years to form and the known viable reserves are being depleted much faster than new ones are being made; the use of fossil fuels raises serious environmental concerns. The burning of fossil fuels produces around 21.3 billion tonnes of carbon dioxide per year. It is estimated that natural processes can only absorb about half of that amount, so there is a net increase of 10.65 billion tonnes of atmospheric carbon dioxide per year.
Carbon dioxide is a greenhouse gas that increases radiative forcing and contributes to global warming. A global movement towards the generation of low-carbon renewable energy is underway to help reduce global greenhouse gas emissions. Aquatic phytoplankton and zooplankton that died and sedimented in large quantities under anoxic conditions millions of years ago began forming petroleum and natural gas as a result of anaerobic decomposition. Over geological time this organic matter, mixed with mud, became buried under further heavy layers of inorganic sediment; the resulting high levels of heat and pressure caused the organic matter to chemically alter, first into a waxy material known as kerogen, found in oil shales, with more heat into liquid and gaseous hydrocarbons in a process known as catagenesis. Despite these heat driven transformations, the embedded energy is still photosynthetic in origin. Terrestrial plants, on the other hand, tended to form methane. Many of the coal fields date to the Carboniferous period of Earth's history.
Terrestrial plants form type III kerogen, a source of natural gas. There is a wide range of organic, or hydrocarbon, compounds in any given fuel mixture; the specific mixture of hydrocarbons gives a fuel its characteristic properties, such as boiling point, melting point, viscosity, etc. Some fuels like natural gas, for instance, contain only low boiling, gaseous components. Others such as gasoline or diesel contain much higher boiling components. Fossil fuels are of great importance because they can be burned, producing significant amounts of energy per unit mass; the use of coal as a fuel predates recorded history. Coal was used to run furnaces for the melting of metal ore. Semi-solid hydrocarbons from seeps were burned in ancient times, but these materials were used for waterproofing and embalming. Commercial exploitation of petroleum began in the 19th century to replace oils from animal sources for use in oil lamps. Natural gas, once flared-off as an unneeded byproduct of petroleum production, is now considered a valuable resource.
Natural gas deposits are the main source of the element helium. Heavy crude oil, much more viscous than conventional crude oil, oil sands, where bitumen is found mixed with sand and clay, began to become more important as sources of fossil fuel as of the early 2000s. Oil shale and similar materials are sedimentary rocks containing kerogen, a complex mixture of high-molecular weight organic compounds, which yield synthetic crude oil when heated; these materials have yet to be exploited commercially. With additional processing, they can be employed in lieu of other established fossil fuel deposits. More there has been disinvestment from exploitation of such resources due to their high carbon cost, relative to more processed reserves. Prior to the latter half of the 18th century and watermills provided the energy needed for industry such as milling flour, sawing wood or pumping water, burning wood or peat provided domestic heat; the widescale use of fossil fuels, coal at first and petroleum to fire steam engines enabled the Industrial Revolution.
At the same time, gas lights using natural gas or coal gas were coming into wide use. The invention of the internal combustion engine and its use in automobiles and trucks increased the demand for gasoline and diesel oil, both made from fossil fuels. Other forms of
Sugarcane, or sugar cane, are several species of tall perennial true grasses of the genus Saccharum, tribe Andropogoneae, native to the warm temperate to tropical regions of South, Southeast Asia, New Guinea, used for sugar production. It has stout, fibrous stalks that are rich in the sugar sucrose, which accumulates in the stalk internodes; the plant is two to six metres tall. All sugar cane species can interbreed and the major commercial cultivars are complex hybrids. Sugarcane belongs to the grass family Poaceae, an economically important seed plant family that includes maize, wheat and sorghum, many forage crops. Sucrose and purified in specialized mill factories, is used as raw material in the food industry or is fermented to produce ethanol. Sugarcane is the world's largest crop by production quantity, with 1.9 billion tonnes produced in 2016, Brazil accounting for 41% of the world total. In 2012, the Food and Agriculture Organization estimated it was cultivated on about 26 million hectares, in more than 90 countries.
The global demand for sugar is the primary driver of sugarcane agriculture. Cane accounts for 79% of sugar produced. Sugarcane predominantly grows in the subtropical regions. Other than sugar, products derived from sugarcane include falernum, rum, cachaça, ethanol. In some regions, people use sugarcane reeds to make pens, mats and thatch; the young, unexpanded inflorescence of Saccharum edule is eaten raw, steamed, or toasted, prepared in various ways in Southeast Asia, including Fiji and certain island communities of Indonesia. Sugarcane was an ancient crop of the Papuan people, it was introduced to Polynesia, Island Melanesia, Madagascar in prehistoric times via Austronesian sailors. It was introduced to southern China and India by Austronesian traders at around 1200 to 1000 BC; the Persians, followed by the Greeks, encountered the famous "reeds that produce honey without bees" in India between the 6th and 4th centuries BC. They adopted and spread sugarcane agriculture. Merchants began to trade in sugar from India, considered a luxury and an expensive spice.
In the 18th century AD, sugarcane plantations began in Caribbean, South American, Indian Ocean and Pacific island nations and the need for laborers became a major driver of large human migrations, both the voluntary in indentured servants. And the involuntary migrations, in the form of slave labor. Sugarcane is a tropical, perennial grass that forms lateral shoots at the base to produce multiple stems three to four m high and about 5 cm in diameter; the stems grow into cane stalk. A mature stalk is composed of 11–16% fiber, 12–16% soluble sugars, 2–3% nonsugars, 63–73% water. A sugarcane crop is sensitive to the climate, soil type, fertilizers, disease control and the harvest period; the average yield of cane stalk is 60–70 tonnes per hectare per year. However, this figure can vary between 30 and 180 tonnes per hectare depending on knowledge and crop management approach used in sugarcane cultivation. Sugarcane is a cash crop, but it is used as livestock fodder. There are two centers of domestication for sugarcane: one for Saccharum officinarum by Papuans in New Guinea and another for Saccharum sinense by Austronesians in Taiwan and southern China.
Papuans and Austronesians primarily used sugarcane as food for domesticated pigs. The spread of both S. officinarum and S. sinense is linked to the migrations of the Austronesian peoples. Saccharum barberi was only cultivated in India after the introduction of S. officinarum. Saccharum officinarum was first domesticated in New Guinea and the islands east of the Wallace Line by Papuans, where it is the modern center of diversity. Beginning at around 6,000 BP they were selectively bred from the native Saccharum robustum. From New Guinea it spread westwards to Island Southeast Asia after contact with Austronesians, where it hybridized with Saccharum spontaneum; the second domestication center is mainland southern China and Taiwan where S. sinense was a primary cultigen of the Austronesian peoples. Words for sugarcane exist in the Proto-Austronesian languages in Taiwan, reconstructed as *təbuS or **CebuS, which became *tebuh in Proto-Malayo-Polynesian, it was one of the original major crops of the Austronesian peoples from at least 5,500 BP.
Introduction of the sweeter S. officinarum may have replaced it throughout its cultivated range in Island Southeast Asia. From Island Southeast Asia, S. officinarum was spread eastward into Polynesia and Micronesia by Austronesian voyagers as a canoe plant by around 3,500 BP. It was spread westward and northward by around 3,000 BP to China and India by Austronesian traders, where it further hybridized with Saccharum sinense and Saccharum barberi. From there it spread further into the Mediterranean; the earliest known production of crystalline sugar began in northern India. The exact date of the first cane sugar production is unclear; the earliest evidence of sugar production comes from ancient Pali texts. Around the 8th century and Arab traders introduced sugar from medieval India to the other parts of the Abbasid Caliphate in the Mediterranean, Egypt, North Africa, Andalusia. By the 10th century, sources state, it was among the early crops brought to the Americas by the Spanish Andalu