Examples of Combination Reaction

A chemical reaction involves the conversion of some starting materials which are called as reactants to different chemical compounds which are called as products. Chemical reactions lead to the formation and breaking of chemical bonds between atoms in the molecules. Let’s discuss a particular type of chemical reaction which are named as combination or synthesis reaction. Direct combination or synthesis reaction involves the combination of two or more chemical species and form a more complex product. The general combination reaction can be written as; 

A + B → AB

Such reactions involve the combination of two or more substances but form only one substance as the final product. For example; the combination of iron and sulphur results the formation iron (II) sulphide as given below;

8 Fe + S8 → 8 FeS

Since such reactions form a new chemical substance therefore they are also called as synthesis reactions. Combination reactions can be classified in three types;
  • Reaction between elements.
  • Reaction between elements and compounds.
  • Reaction between compounds.
The reaction of sodium with chlorine form sodium chloride. It shows the combination of two elements; sodium and chlorine element. One is metal here and another is non-metal whereas product is an ionic compound.

2Na(s) + Cl2(g) → 2NaCl (g) 

The combination of two non-metals forms covalent compounds such as combination of solid sulphur and oxygen gas forms sulphur dioxide gas.
S(s)  + O2(g) → SO2(g)

The combination reaction of oxygen molecule with carbon monoxide gas forms carbon dioxide. It is an example of combination of elements and compounds.
O2(g) + 2CO(g) → 2CO2(g)

Similarly the combination of two compounds can form a new compound such as combination of calcium oxide with carbon dioxide gas forms calcium carbonate.
CaO(s) + CO2(g) → CaCO3(s)

Combination or synthesis reactions are exothermic in nature because they involve the formation of new bonds and release a large amount of energy in the form of heat.Another example of combination reaction is the formation of calcium hydroxide by the reaction of quick lime with water. Calcium hydroxide is also called as slaked lime. It is highly vigorous and exothermic reaction.

CaO(s) + H2O(l)  Ca(OH)2(s)

Some of the combustion reactions are also example of combination reaction such as combustion of coal or hydrogen in the presence of oxygen result the formation of carbon dioxide and water respectively. Both are example of combination reactions. 

C(s)  + O2(g) → CO2(g)
2H2(g) + O2(g) → 2H2O (l)

When ammonia gas reacts with hydrogen chloride gas, it forms ammonium chloride which is a white colour solid.

NH3(g) + HCl (g) NH4Cl(s)

Formation of sulphuric acid form the combination of sulphur trioxide and water is also a combination reaction which is again highly exothermic reaction. 
SO3(g) + H2O(l) H2SO4(l)

Formation of black ferrous sulphide form solid iron and sulphur is also a combination reaction.

Fe(s) + S(S) FeS(s)

Another example of combination reaction is Heber’s process which involves the combination of nitrogen and hydrogen gas to form ammonia.
N2(g) + H2(g) NH3(g)

Similarly combination of aluminium with oxygen forms aluminium oxide and combination of potassium with chlorine gas forms potassium chloride.
4 Al(s) + 3 O2(g) → 2 Al2O3(s)
2 K(s) + Cl2(g) → 2 KCl(s)


Best Results From Wikipedia Yahoo Answers Youtube


From Wikipedia

Organic Reactions

Organic Reactions is a secondary reference which synthesizes the organic chemistry literature around particular chemical transformations. Each chapter of Organic Reactions is devoted to a particular organic chemical reaction, and chapters provide exhaustive coverage of literature work in the form of a tabular survey of known reactions. Mechanistic and experimental details, including the scope and limitations of each transformation, are also included.

Organic Reactions is a comprehensive reference work that contains authoritative, critical reviews of many important synthetic reactions. Authors for these chapters are solicited by the board of editors from leading chemists worldwide. The publication process entails a thorough peer-review process, ensuring the high quality and attention to detail for which this series is noted. Organic Reactions chapters focus primarily on the preparative aspects of a given transformation. Particular attention is paid to substrate scope, reaction limitations, stereochemical aspects, effects of chemical structures, and the selection of experimental conditions. Detailed procedures illustrating the significant modifications of the chemical reaction are also included, along with comparisons to other methods to achieve a similar transformation. Every chapter contains a comprehensive compilation all of the published examples of the reaction organized in tables according to the structure of the starting material. Each reaction is presented with information about the reaction conditions, yield, products, and is fully referenced.

Aims

The aim of Organic Reactions since its initial publication in 1942 has been to assist organic chemists in the design of new experiments by providing "critical discussions of the more important synthetic reactions." Organic Reactions is unique in providing an authoritative discussion of the topic reaction accompanied by tables that organize all published examples of the reaction being reviewed. This combination of critical discussion and thorough coverage is responsible for the leading position this series occupies for scientists interested in the reactions of organic chemistry. An additional distinctive feature of this series is that it is assembled almost entirely through voluntary dedicated efforts of its authors, editors and assistants.

The Organic Reactions book series is owned and copyrighted by Organic Reactions, Inc. a not-for-profit, private operating foundation incorporated in the state of Illinois. The books are published by John Wiley and Sons, Inc. who also manage and maintain the [http://onlinelibrary.wiley.com/book/10.1002/0471264180 Organic Reactions website].

History

The decision to undertake the preparation and presentation of "critical discussions of the more important (synthetic) reactions" was made at a meeting of the editors of Organic Syntheses and representatives of John Wiley & Sons during the Eighth National Organic Chemistry Symposium at St. Louis in December 1939. At that meeting the organizational setup was agreed upon, the operating procedures were roughed out, and the topics and authors were selected for Volume 1. These actions were formalized by the incorporation of Organic Reactions in Illinois on August 1, 1942, for educational and research purposes, with Roger Adams, Harold R. Snyder, Werner E. Bachmann, John R. Johnson, and Louis F. Fieser as directors, and by the appearance later that year of Volume 1. Roger Adams was elected president and served as President and Editor-in-Chief until he was succeeded in both positions by Arthur C. Cope in 1960 with the publication of Volume 11. He remained an active member of the Editorial Board until his death in 1971. Professor Cope in turn was succeeded in 1966 by Professor William G. Dauben who served from 1966-1984. Subsequent Editors-in-Chief and Presidents of the corporation are: Professor Andrew S. Kende (1984–1988), Professor Leo A. Paquette (1988–2000) Professor Larry E. Overman (2000–2007) and Professor Scott E. Denmark (2008–present). The close relationship of Organic Reactions to Organic Syntheses, Roger Adams, and John Wiley & Sons is obvious; the great value of that relationship is equally obvious to all who have been connected with the series as editors and authors.


Oxymercuration reaction

The oxymercuration reaction is an electrophilic additionorganic reaction that transforms an alkene into a neutral alcohol. In oxymercuration, the alkene reacts with mercuric acetate (AcO-Hg-OAc) in aqueous solution to yield the addition of an acetoxymercuri (HgOAc) group and a hydroxy (OH) group across the double bond. Carbocations are not formed in this process and thus rearrangements are not observed. The reaction follows Markovnikov's rule (the hydroxy group will always be added to the more substituted carbon) and it is an anti addition (the two groups will be trans to each other) .

Oxymercuration followed by demercuration is called an oxymercuration-reduction reaction. This reaction, which is almost always done in practice instead of oxymercuration, is treated at the conclusion of the article.

Mechanism

Oxymercuration can be fully described in three steps(the whole process is sometimes called deoxymercuration), which is illustrated in stepwise fashion to the right. In the first step, the nucleophilic double bond attacks the mercury ion, ejecting an acetoxy group. The electron pair on the mercury ion in turn attacks a carbon on the double bond, forming a mercurinium ion in which the mercury atom bears a positive charge. The electrons in the highest occupied molecular orbital of the double bond are donated to mercury's empty dz2 orbital and the electrons in mercury's dxz orbital are donated in the lowest unoccupied molecular orbital of the double bond.

In the second step, the nucleophilic water molecule attacks the more substituted carbon, liberating the electrons participating in its bond with mercury. The electrons collapse to the mercury ion and neutralizes it. The oxygen in the water molecule now bears a positive charge.

In the third step, the negatively charged acetoxy ion that was expelled in the first step attacks a hydrogen of the water group, forming the waste product HOAc. The two electrons participating in the bond between oxygen and the attacked hydrogen collapse into the oxygen, neutralizing its charge and creating the final alcohol product.

Regioselectivity and stereochemistry

Oxymercuration is very regioselective and is a textbook Markovnikov reaction; ruling out extreme cases, the water nucleophile will always preferentially attack the more substituted carbon, depositing the resultant hydroxy group there. This phenomenon is explained by examining the three resonance structures of the mercurinium ion formed at the end of the step one.

By inspection of these structures, it is seen that the positive charge of the mercury atom will sometimes reside on the more substituted carbon (approximately 4% of the time). This forms a temporary tertiary carbocation, which is a very reactive electrophile. The nucleophile will attack the mercurinium ion at this time. Therefore, the nucleophile attacks the more substituted carbon because it retains more positive character than the lesser substituted carbon.

Stereochemically, oxymercuration is an anti addition. As illustrated by the second step, the nucleophile cannot attack the carbon from the same face as the mercury ion because of steric hindrance. There is simply insufficient room on that face of the molecule to accommodate both a mercury ion and the attacking nucleophile. Therefore, when free rotation is impossible, the hydroxy and acetoxymercuri groups will always be trans to each other.

Shown below is an example of regioselectivity and stereospecificity of the oxymercuration reaction with substituted cyclohexenes. A bulky group like t-butyl locks the ring in a chair conformation and prevents ring flips. With 4-t-butylcyclohexene, oxymercuration yields two products - where addition across the double bond is always anti - with slight preference towards acetoxymercury group trans to the t-butyl group, resulting in slightly more cis product. With 1-methyl-4-t-butylcyclohexene, oxymercuration yields only one product - still anti addition across the double bond - where water only attacks the more substituted carbon. The reason for anti addition across the double bond is to maximize orbital overlap of the lone pair of water and the empty orbital of the mercurinium ion on the opposite side of the acetoxymercury group. Regioselectivity is observed to favor water attacking the more subsituted carbon, but water does not add syn across the double bond which implies that the transition state favors water attacking from the opposite side of the acetomercury group.

Oxymercuration-reduction

In practice, the mercury adduct product created by the oxymercuration reaction is almost always treated with sodium borohydride (NaBH4) in aqueous base in a reaction called demercuration. In demercuration, the acetoxymercury group is replaced with a hydrogen in a stereochemically insensitive reaction known as reductive elimination. The combination of oxymercuration followed immediately by demercuration is called an oxymercuration-reduction reaction.

Therefore, the oxymercuration-reduction reaction is the net addition of water across the double bond. Any stereochemistry set up by the oxymercuration step is scrambled by the demercuration step, so that the hydrogen and hydroxy group may be cis or trans from each other. Oxymercuration-reduction is a popular laboratory technique to achieve alkene hydration with Markovnikov selectivity while avoiding carbocation intermediates and thus the rearrangement which can lead to complex product mixtures.

Other Applications of the Oxymercuration Reaction

Oxymercuration is not limited to an alkene reacting with water. Using an alkyne instead of an alkene yields an enol, which tautomerizes into a ketone. Using an alcohol instead of water yields an ether. In both cases, Markovnikov's rule is observed.

Using a vinyl ether in the presence of an alcohol allows the transfer of the alkoxy group (RO-) from the alcohol to the ether. An allyl alcohol and a vinyl ether under the conditions of oxymercuration reaction can give R-CH=CH-CH2-O-CH=CH2, which is suitable for a Claisen Rearrangement.


Affine combination

In mathematics, an affine combination of vectors x1, ..., xn is vector

\sum_{i=1}^{n}{\alpha_{i} \cdot x_{i}} = \alpha_{1} x_{1} + \alpha_{2} x_{2} + \cdots +\alpha_{n} x_{n},

called the linear combination of x1, ..., xn , in which the sum of the coefficients is 1, thus:

\sum_{i=1}^{n} {\alpha_{i}}=1.

Here the vectors are elements of a given vector spaceV over a fieldK, and the coefficients \alpha _{i} are scalars in K.

This concept is important, for example, in Euclidean geometry.

An affine combination of fixed points of an affine transformation is also a fixed point, so the fixed points form an affine subspace (in 3D: a line or a plane, and the trivial cases, a point and the whole space).

When a stochastic matrix, A, acts on a column vector, B, the result is a column vector whose entries are affine combinations of B with coefficients from the rows in A.


Combining form

In the linguistics of word formation, a combining form (also neoclassical element) is a bound base designed to combine with another combining form or a free word. For example, bio- combines with -graphy to form biography.

Words with combining forms are variously called combining form compounds, neoclassical compounds, and classical compounds.

A vowel usually facilitates the combination: in biography, the Greek thematic vowel -o-, in miniskirt, the Latin thematic -i-. This vowel is usually regarded as attached to the initial base (bio-, mini-) rather than the final base (-graphy, -skirt), but in Greek-derived forms it is sometimes shown as attached to the final base (-ography, -ology). If, however, the final base begins with a vowel (for example, -archy as in monarchy), the mediating vowel has traditionally been avoided (no *monoarchy), but in recent coinages it is often kept and generally accompanied by a hyphen (auto-analysis, bio-energy, hydro-electricity, not *autanalysis, *bienergy, *hydrelectricity).

Translation

There are hundreds of combining forms in English and other European languages. As traditionally defined, they cannot stand alone as free words, but there are many exceptions to this rule, and in the late 20th century such forms are increasingly used independently: bio as a clipping of biography, telly as a respelt clipping of television. Most combining forms translate readily into everyday language, especially nouns: bio- as ‘life’ -graphy as ‘writing, description’. Because of this, the compounds of which they are part (usually classical or learned compounds) can be more or less straightforwardly paraphrased: biography as ‘writing about a life’, neurology as ‘the study of the nervous system’. Many combining forms are designed to take initial or final position: autobiography has the two initial or preposed forms auto-, bio-, and one postposed form -graphy. Although most occupy one position or the other, some can occupy both: -graph- as in graphology and monograph; -phil- as in philology and Anglophile. Occasionally, the same base is repeated in one word: logology the study of words, phobophobia the fear of fear.

Preposed and postposed

Forms that come first include: aero- air, crypto- hidden, demo- people, geo- earth, odonto- tooth, ornitho- bird, thalasso sea. Many have both a traditional simple meaning and a modern telescopic meaning: in biology, bio- means ‘life’, but in bio-degradable it telescopes ‘biologically’; although hypno- basically means ‘sleep’ (hypnopaedia learning through sleep), it also stands for ‘hypnosis’ (hypnotherapy cure through hypnosis). When a form stands alone as a present-day word, it is usually a telescopic abbreviation: bio biography, chemo chemotherapy, hydro hydroelectricity, metro metropolitan. Some telescoped forms can be shorter than the original combining forms: gynie is shorter than gyneco- and stands for both gynecology and gynecologist; anthro is shorter than anthropo- and stands for anthropology. Forms that come second include: -ectomy cutting out, -graphy writing, description, -kinesis motion, -logy study, -mancy divination, -onym name, -phagy eating, -phony sound, -therapy healing, -tomy cutting. They are generally listed in dictionaries without the interfixed vowel, which appears however in such casual phrases as ‘ologies and isms’.

Variants

Some combining forms are variants of one base.

Some are also free words, such as mania in dipsomania and phobia in claustrophobia.

Some are composites of other elements, such as encephalo- brain, from en- in, -cephal- head, and -ectomy cutting out, from ec- out, -tom- cut, -y, a noun-forming suffix that means "process of".

Origins

In Greek and Latin grammar, combining bases usually require a thematic or stem-forming vowel. In biography, from Greek, the thematic is -o-; in agriculture, from Latin, it is -i-. In English, which does not inflect in this way and has no native thematic vowels, an element like -o- is an imported glue that holds bases together. Its presence helps to distinguish classical compounds like biography and agriculture from vernacular compounds like teapot and blackbird. Generally, English has acquired its classical compounds in three ways: through French from Latin and Greek, directly from Latin and Greek, and by coinage in English on Greek and Latin patterns. An exception is schizophrenia, which came into English through German, and is therefore pronounced ‘skitso’, not ‘skyzo’. The combining forms and the compounds built from them are as much a part of English as of Latin and Greek, and as much a part of French, Spanish, Italian, and any other language that cares to use them. They are an international resource.

The conservative tradition

From the Renaissance until the mid-20th century, the concept of derivational purity has generally regulated the use of combining forms: Greek with Greek, Latin with Latin, and a minimum of hybridization. Biography is Greek, agriculture Latin, but television is a hybrid of Greek tele- and Latin -vision (probably so coined because the ‘pure’ form telescope had already been adopted for another purpose). Most dictionaries follow the OED in using combining form (comb. form) to label such classical elements, but the name is not widely known. In appendices to dictionaries and grammar books, combining forms are often loosely referred to as roots or affixes: ‘a logo …, properly speaking, is not a word at all but a prefix meaning word and short for logogram, a symbol, much as telly is short for television’ (Montreal Gazette, 13 Apr. 1981). They are often referred to as affixes because some come first and some come last, but if they were affixes, a word like biography would have no base whatever. While affixes are grammatical (like prepositions), combining forms are lexical (like nouns, adjectives, and verbs): for example, bio- translates as a noun (life), -graphy as a verbal noun (writing). They are also often loosely called roots because they are ancient and have a basic role in word formation, but functionally and often structurally they are distinct from roots: the -graph in autograph is both a root and a combining form, while the -graphy in cryptography consists of root -graph- and suffix -y, and is only a combining form.

Contemporary developments

Generally, combining forms were a closed system from the 16c to the earlier 20c: the people who used them were classically educated, their teachers and exemplars generally took a purist's view on their use, contexts of use were mainly technical, and there was relatively little seepage into the languag


From Yahoo Answers

Question:i need 25 examples of combination reaction

Answers:And you really ( that is really, really) expect some kind hearted contributor to sit down and do this for you? My opinion - NO CHANCE.

Question:e.gCaCO3+H2O+CO2=>Ca[HCO3]2

Answers:Yes

Question:i nid 3 examples in each type of chemical reaction with explanation why they are supposed to combine...

Answers:Rather than reinvent the wheel, you can find some examples at these sites: http://misterguch.brinkster.net/6typesofchemicalrxn.html http://dbhs.wvusd.k12.ca.us/webdocs/Equations/Equations.html http://www.sparknotes.com/testprep/books/sat2/chemistry/chapter6section2.rhtml http://www.fordhamprep.org/gcurran/sho/sho/lessons/lesson82.htm

Question:What are 5 real life examples of the 5 type of reactions? Combination/Synthesis Reaction Decomposition Reaction Single-Replacement Reaction Double-Replacement Reaction Combustion Reaction

Answers:Combination: the rusting of iron (4Fe + 3O2 2Fe2O3) Decomposition: the production of quicklime (Ca(OH)2 CaO + H2O) Single displacement: the polishing of silverware by soaking with aluminium (2Al + 3Ag2S 6Ag + Al2S3) Double displacement: the extraction of magnesium from seawater (MgCl2 + 2NaOH Mg(OH)2 + 2NaCl) Combustion: burning natural gas for heat (CH4 + 2O2 CO2 + 2H2O)

From Youtube

Combinations - Counting Using Combinations :Counting Using Combinations - Math Help. A few numerical examples along with some word problems are shown where combinations are used to count the number of ways some event can occur. For more free math videos, visit PatrickJMT.com austin math tutoring, austinmathtutor, austin math tutor, justmathtutoring.com

Decomposition Reaction Example :This is a short explaination, along with an example, of a decomposition reaction for my 9th grade chemistry project.