House of Bourbon-Parma
The Bourbons of Parma are a royal family who ruled the Duchy of Parma from 1748 till 1860 when Italy was created. The family was founded by the Infante Philip of Spain, third son of Philip V of Spain and Elisabetta Farnese. The Treaty of Aix-la-Chapelle (1748) ended the War of the Austrian Succession, and gave the land to Philip.
Philip married Louise Élisabeth of France and the present pretending duke of Parma (Carlos/Carlo of Parma) is a direct descendant. The duchy was taken by the House of Savoy when the state of Italy was created.
English poetry
The history of English poetry stretches from the middle of the 7th century to today. Over this period, English poets have written some of the longest-surviving poems in Western culture. The language and its poetry have spread around the world.
The earliest surviving poetry from the area now called England was probably transmitted orally (or passed from person to person by mouth, without being written down). It was then written down in versions that do not now survive. Because of this, it is difficult to say which poems were the earliest. There is a lot of controversy over this issue.
A number of major national poetries have developed. These include American, Australian, New Zealand, Canadian and Indian poetry. It may be controversial to describe Irish literature as English or British, even though it is in the English language.
Rearrangement reaction
A rearrangement reaction are organic reactions where the carbon skeleton of a molecule is rearranged. The result is a structural isomer of the original molecule. Often a substituent moves from one atom to another atom in the same molecule. In the example below, the substituent R moves from carbon atom 1 to carbon atom 2:
Intermolecular rearrangements also take place.
Sometimes chemists draw diagrams with arrows that show how electrons are transferred between bonds during a rearrangement reaction. Many organic chemistry text books have such diagrams. But they do not tell the full story of the reaction mechanism. The actual mechanism of a rearrangement with an alkyl group moving is for the group to slide smoothly along a bond, not ionic bond-breaking and forming. One example of this is the Wagner-Meerwein rearrangement:
In pericyclic reactions, the orbital interactions are important. The reactions can not be explained by a series of simple discrete electron transfers. But, the curved arrows showing a sequence of discrete electron transfers can give the same result as a rearrangement reaction. Yet, the diagrams are not necessarily realistic. In allylic rearrangement, the reaction is ionic.
Three important rearrangement reactions are 1,2-rearrangements, pericyclic reactions and olefin metathesis.
A 1,2-rearrangement is an organic reaction where a substituent moves from one atom to another atom in a chemical compound. In a 1,2 shift, the substituent moves between two adjacent atoms. But moves over larger distances are possible. Examples are the Wagner-Meerwein rearrangement:
and the Beckmann rearrangement:
A pericyclic reaction is a type of reaction with multiple carbon-carbon bond making and breaking. The transition state of the molecule has a cyclic geometry. The reaction progresses in a concerted fashion. Examples are hydride shifts
and the Claisen rearrangement:
Olefin metathesis is a formal exchange of the alkylidene fragments in two alkenes. It is a catalytic reaction with carbene. It has transition metal carbene complex intermediates.
Computational chemistry
Computational chemistry is a branch of chemistry that uses computer science to help solve chemical problems. These programs calculate the structures and properties of molecules and solids. Computational chemistry normally complements the information obtained by chemical experiments. It can predict chemical phenomena that have not yet been observed. It is widely used in the design of new drugs and materials.
Computational chemistry can predict structure (that is, the expected positions of the molecule's atoms), absolute and relative (interaction) energies, electronic charge distributions, dipoles and higher multipole moments, vibrational frequencies, reactivity or other spectroscopic quantities, and cross sections for collision with other particles.
Computational chemistry looks at both static and dynamic systems. In all cases, as the size of the system being studied grows, the computer time and other resources (such as memory and disk space) used also grows. That system can be a single molecule, a group of molecules, or a solid. Computational chemistry methods range from highly accurate to very approximate. Highly accurate methods are typically feasible only for small systems.
Polymer chemistry
Polymer chemistry (also called macromolecular chemistry) is the science of chemical synthesis and chemical properties of polymers or macromolecules. According to IUPAC recommendations, macromolecules refer to the individual molecular chains and are the domain of chemistry. Polymers describe the bulk properties of polymer materials and belong to the field of polymer physics (a part of physics).
The different kinds of macromolecules include:
Polymers are formed by polymerization of monomers. Chemists describe a polymer by its degree of polymerization, molar mass distribution, tacticity, copolymer distribution, the degree of branching, by its end-groups, crosslinks, and crystallinity. Chemists also study a polymer's thermal properties such as its glass transition temperature and melting temperature. Polymers in solution have special characteristics for solubility, viscosity and gelation.
Polymer chemistry started by studying the long fibers in plants. The work of Henri Braconnot in 1777 and the work of Christian Schönbein in 1846 led to the discovery of nitrocellulose. Nitrocellulose treated with camphor makes celluloid. Chemists dissolve celluloid in ether or acetone to make collodion. Doctors have used collodion as a wound dressing since the U.S. Civil War. Cellulose acetate was first prepared in 1865. In 1834, Friedrich Ludersdorf and Nathaniel Hayward independently discovered that adding sulfur to raw natural rubber (polyisoprene) helped prevent the material from becoming sticky. In 1844 Charles Goodyear received a U.S. patent for vulcanizing rubber with sulfur and heat. Thomas Hancock had received a patent for the same process in the UK the year before.
In 1884, Hilaire de Chardonnet started the first artificial fiber factory based on regenerated cellulose, or viscose rayon, as a substitute for silk, but it was very flammable. In 1907 Leo Baekeland invented the first synthetic polymer, a thermosetting phenol-formaldehyde resin called Bakelite. Around the same time, Hermann Leuchs reported the synthesis of N-carboxyanhydrides and their high molecular weight products upon reaction with nucleophiles. But Leuchs did not call them polymers, possibly due to the strong views held by Emil Fischer, his direct supervisor, denying the possibility of any covalent molecule exceeding 6,000 daltons. Cellophane was invented in 1908 by Jocques Brandenberger who squirted sheets of viscose rayon into an acid bath.
In 1922, Hermann Staudinger (a German chemist) proposed that polymers were long chains of atoms held together by covalent bonds. He also proposed to name these compounds "macromolecules". Before that, scientists believed that polymers were clusters of small molecules (called colloids), without definite molecular weights, held together by an unknown force. Staudinger received the Nobel Prize in Chemistry in 1953.