In chemistry, an ester is a chemical compound derived from an acid in which at least one –OH group is replaced by an –O–alkyl group. Esters are derived from a carboxylic acid and an alcohol. Glycerides, which are fatty acid esters of glycerol, are important esters in biology, being one of the main classes of lipids, making up the bulk of animal fats and vegetable oils. Esters with low molecular weight are used as fragrances and found in essential oils and pheromones. Phosphoesters form the backbone of DNA molecules. Nitrate esters, such as nitroglycerin, are known for their explosive properties, while polyesters are important plastics, with monomers linked by ester moieties. Esters have a sweet smell and are considered high-quality solvents for a broad array of plastics, plasticizers and lacquers, they are one of the largest classes of synthetic lubricants on the commercial market. The word ester was coined in 1848 by a German chemist Leopold Gmelin as a contraction of the German Essigäther, "acetic ether".

Ester names are derived from the parent alcohol and the parent acid, where the latter may be organic or inorganic. Esters derived from the simplest carboxylic acids are named according to the more traditional, so-called "trivial names" e.g. as formate, acetate and butyrate, as opposed to the IUPAC nomenclature methanoate, ethanoate and butanoate. Esters derived from more complex carboxylic acids are, on the other hand, more named using the systematic IUPAC name, based on the name for the acid followed by the suffix -oate. For example, the ester hexyl octanoate known under the trivial name hexyl caprylate, has the formula CH36CO25CH3; the chemical formulas of organic esters take the form RCO2R′, where R and R′ are the hydrocarbon parts of the carboxylic acid and the alcohol, respectively. For example, butyl acetate, derived from butanol and acetic acid would be written CH3CO2C4H9. Alternative presentations are common including BuOAc and CH3COOC4H9. Cyclic esters are called lactones, regardless of whether they are derived from an organic or an inorganic acid.

One example of an organic lactone is γ-valerolactone. An uncommon class of organic esters are the orthoesters, which have the formula RC3. Triethylorthoformate is derived, in terms of its name from orthoformic ethanol. Esters can be derived from an inorganic acid and an alcohol. Thus, the nomenclature extends to inorganic oxo acids and their corresponding esters: phosphoric acid and phosphate esters/organophosphates, sulfuric acid and sulfate esters/organosulfates, nitric acid and nitrate, boric acid and borates. For example, triphenyl phosphate is the ester derived from phosphoric phenol. Organic carbonates are derived from carbonic acid. So far an alcohol and inorganic acid are linked via oxygen atoms; the definition of inorganic acid ester that feature inorganic chemical elements links between alcohols and the inorganic acid – the phosphorus atom linking to three alkoxy functional groups in organophosphate – can be extended to the same elements in various combinations of covalent bonds between carbons and the central inorganic atom and carbon–oxygen bonds to central inorganic atoms.

For example, phosphorus features three carbon–oxygen–phosphorus bonds and one phosphorus–oxygen double bond in organophosphates, three carbon–oxygen–phosphorus bonds and no phosphorus–oxygen double bonds in phosphite esters or organophosphites, two carbon–oxygen–phosphorus bonds, no phosphorus–oxygen double bonds but one phosphorus–carbon bond in phosphonites, one carbon–oxygen–phosphorus bonds, no phosphorus–oxygen double bonds but two phosphorus–carbon bonds in phosphinites. In corollary, boron features borinic esters, boronic esters, borates; as oxygen is a group 16 chemical element, sulfur atoms can replace some oxygen atoms in carbon–oxygen–central inorganic atom covalent bonds of an ester. As a result and thiosulfonates, with a central inorganic sulfur atom, demonstrate the assortment of sulfur esters, that includes sulfates, sulfonates, sulfenates esters. Esters contain a carbonyl center, which gives rise O -- C -- O angles. Unlike amides, esters are structurally flexible functional groups because rotation about the C–O–C bonds has a low barrier.

Their flexibility and low polarity is manifested in their physical properties. The pKa of the alpha-hydrogens on esters is around 25. Many esters have the potential for conformational isomerism, but they tend to adopt an s-cis conformation rather than the s-trans alternative, due to a combination of hyperconjugation and dipole minimization effects; the preference for the Z conformation is influenced by the nature of the substituents and solvent, if present. Lactones with small rings are restricted to the s-trans conformation due to their cyclic structure. Esters are less polar than alcohols, they participate in hydrogen bonds as hydrogen-bond acceptors, but cannot act as hydrogen-bond donors, unlike their parent alcohols. This ability to participate in hydrogen bonding confers some water-solubility; because of their lack of hydrogen-bond-donating ability, esters do not self-associate. Esters are more volatile than carboxylic acids of similar molecular weight. Esters are identified by gas chromatography, taking advantage of their volatil

Leopold II, Prince of Lippe

Leopold II of Lippe was the sovereign of the Principality of Lippe. He succeeded to the throne in 1802, in 1820 he assumed control of the government from his mother, acting as regent due to his youth at accession. Leopold II was born in Detmold, the eldest child of Leopold I, the reigning prince of Lippe and his consort Princess Pauline of Anhalt-Bernburg, he succeeded as Prince of Lippe on his father's death on 5 November 1802. As he was just six years old, his mother Princess Pauline acted as regent until 3 July 1820, when he assumed control of the government. During the regency, his mother had introduced a constitution in 1819 which created an assembly which at the time had more executive powers than any other assembly in Germany. In 1825 he constructed a Court Theatre. Among those to perform at the theatre were Albert Lortzing and Ludwig Devrient who were employed there from 1826 to 1833. In the last years of his reign the revolutions of 1848 broke out across all of Germany. Following his death in Detmold he was succeeded on the throne by his eldest son Leopold III.

Prince Leopold was married in Arnstadt on 23 April 1820 to Princess Emilie of Schwarzburg-Sondershausen. They had nine children: Leopold III, Prince of Lippe, married to princess Elisabeth of Schwarzburg-Rudolstadt on 17 April 1852. Princess Luise of Lippe Woldemar, Prince of Lippe, married to princess Sophie of Baden on 9 November 1858. Princess Friederike of Lippe Prince Friedrich of Lippe Prince Hermann of Lippe Alexander, Prince of Lippe Prince Karl of Lippe Princess Pauline of Lippe

Ullin station

Ullin station is a former Illinois Central Railroad station located at the intersection of Central Ave. and Ullin Ave. in Ullin, Illinois. Illinois Central service to Ullin began in 1854, two stations were constructed in 1854 and 1863, both of which were demolished; the existing station was built in 1897. The station provided passenger rail service to Ullin. In addition, the depot served as Ullin's telegraph station, as the area's telegraph lines followed the Illinois Central tracks. Passenger service to the station ended in 1967, the station moved to a new location in 1972, it was moved back to its original site in 1997 and became Ullin's village hall and library in 2012. The station was added to the National Register of Historic Places on August 18, 1999 as the Illinois Central Railroad Depot