Compounds nitrogen

Nitrogen is one of the most plentiful elements in the universe. Indeed, the earth s atmosphere contains nearly 80% nitrogen in molecular form. The presence of this uncombined element indicates that nitrogen s chemical reactivity is extremely low. One illustration of this in winemaking is the use of a blanket of nitrogen to protect wines in partially empty vats. Animal and plant cells cannot assimilate molecular nitrogen, so it must be obtained in mineral or organic forms. 

Total nitrogen in must or wine includes one inorganic form and various organic forms. Total 

Handbook of Enology Volume 2 The Chemistry of Wine and Stabilization and Treatments P. Ribereau-Gayon, Y. Glories, A. Maujean and D. Dubourdieu 2006 John Wiley Sons, Ltd 

Red wines have average nitrogen concentrations almost twice as high as those of white wines. This is dne to winemaking techniqnes, inclnding high-temperature maceration, which causes nitrogenated substances to dissolve more readily from the skins and seeds, as well as autolysis of dead yeast cells. 

The total nitrogen concentration of Bordeaux wines varies from 70 to 700 mg/1. Values in white wines range from 77 to 377 mg/1, with an average of 185 mg/1. Red wines have nitrogen contents between 143 and 666 mg/1, with an average of 330 mg/1 (Ribereau-Gayon et al, 1982). 

The nitrogen contained in organic substances in water is converted to ammonium ions by KjeldahEs decomposition method. The ammonium ions are distilled from alkaline solution as ammonia, collected in boric acid solution and determined acidimetrically or photometrically in the receiver. Ammonium ions originally contained in the sample are separated, identified and deducted, or separated off by distillation before carrying out the Kjeldahl decomposition. Nitrite and nitrate are volatilized by H2SO4 in the 

The method is suitable for the determination of organically bonded nitrogen in concentrations greater than about 0.2 mg/1. Aromatic and heterocyclic compounds with N atoms in the ring are only partially detected. 

Determine separately the content of nitrate, nitrite and ammonium ions in the water, convert the results to mg/1 N and add to the content of organically bonded nitrogen in mg/1 N  

D = Content of organically bonded nitrogen in the sample in mg/1 N Conversion factors 

Distillation apparatus with receiver Sulphuric acid, cone., (1.84 g/ml) 

Nitrogen Compounds.—The formation of ZrNj 9 by a new method of evaporation synthesis has been described. The compound LiZrN2 has been prepared from LijN and ZrNi 22 and X-ray crystallographic studies have shown that the crystals contain hexagonally close-packed nitride ions, with Zr and Li ions in octahedral and tetrahedral holes, respectively.  

CCliCN and ZrCl4.,CH2ClCN have been prepared from ZrCl and the corresponding chlorinated nitrile the former has been shown to be iso-morphous with TiCl4,CCl3CN, and is thus a chloride-bridged dimer, with each Zr octahedrally co-ordinated.  

The reaction of Zr(OPr ) with the Schiff bases acetylacetone-2-hydroxy-alkylimine, N-[(3-hydroxy-2-naphthyl)methylene]-2-hydroxyalkylamine, and o-hydroxyacetophenone-2-hydroxyalkylimine (HL) affords the polymeric Zr(OPr )2L and ZrL2 compounds. N.m.r. and i.r. spectral studies indicated that the N atom of the Schiff base is co-ordinated in these compounds. 

The stepwise stability constants for zirconium and hafnium thiocyanato-complexes have been determined by solvent-extraction techniques. The values ) i = 12.1 2.2, = 215 11, P4. = 205 + 20 for zirconium, and Pi = 

McGinnis and J. B. Hamilton, Inorg. Nuclear Chem. Letters, 1972, 8,245. 

Simple oxides of nitrogen are covered in the final section of this chapter. The lifetimes of various levels of the A2%-, 2 , and C2 + states of NH+ (and OH+ and SH+) have been determined and found to lie between 1.09 fjts and 390 ns.87 Emission from the 2 B1, and t 1 states of the neutral NH species produced in the photolysis of ammonia in the vacuum-u.v. has been observed.88 Threshold energies for various products were determined as shown in Table 4. 

Brzozowski, N. Elander, P. Erman, and M. Lyyra, Physica Scripta, 1974, 10, 241. 

The NH2 produced in reaction (50) has been studied by laser-excited fluorescence,89 and the rate of the reaction between ground-state NH2 and NO was determined as 1.26 x 10101 mol-1 s-1 at 298 K. 

The photoionization yields of trimethylamine, dipropylamine, di-isopropylamine, and tetramethylene sulphide at 147 nm have been determined as 0.38, 0.46, 0.096, 0.15, and 0.10 respectively, and their use as actinometers at this wavelength has been advocated.94 Photoionization and ion-molecule reactions in propyl-, ethyl-, diethyl-, and triethyl-amines have also been discussed,95 and striking differences between the vapour-phase and solution-phase photochemical 88 

Hancock, W. Lange, M. Lenzi, and . H. Welge, Chem. Phys. Letters, 1975, 33, 168. 

These equations show how nitrogen from the air ends up in so many other chemical products. It would be hard to imagine what the world would be like if no one had discovered how to convert nitrogen from the air to usable chemicals. 

The hydrogen for reaction with nitrogen in the air is obtained by reacting methane (from natural gas found in underground deposits) with water, as shown in the above equation. 

Currently, nitrogen compounds are not very widely used as flame retardants, but some growth is now expected. The best known is melamine, although benzoguanamine and acetoguanamine are possible alternatives. Melamine phosphate is used in conjunction with phosphorus compounds in intumescent compositions. Melamine diborate has been used in epoxy polymers, and melamine cyanurate in polyamides. 

A number of compounds containing both nitrogen and phosphorus are currently being investigated, such as the reaction product from tri(diethanolaminemethyl) melamine and orthophosphoric acid. 

Besides being used as a component of intumescent systems, melamine is capable of acting as a relatively cheap flame retardant by virtue of the following mechanisms  

Melamine has been used in polyolefins and polystyrene. Melamine cyanurate is preferred in polyamides because it is more thermally stable. 

Interest in tin compoimds as flame retardants for plastics has grown over the past 15 years. More than a dozen substances have been tried with some success, but only three of them, namely zinc hydroxystannate, zinc stannate and zinc oxide, are currently important. They all have low toxicity. Zinc stannate is preferred for use in polymers processed at temperatures over 

Oxidations of nitrogen compounds include oxidation at nitrogen as well as oxidations at carbons carrying the nitrogen functional groups. 

The structure of HeJSi iMe2 116K shows nitrogen slightly non-planar with the Si-N bond (171.9pm) a little longer than in the vapour, that of silylated 

supporting iminosilane character, but reacts with Me SiCl to give the 

A series of cadmium amides C(R Si)2H32Cd and their complexes (R Me) with 

skeleton for Si2l MWSi2 in the vapour phase. The structures of C(Me2Si 2N3 M (M=Ce,Pr show a nonrplanar skeleton, while the derivatives with M=Sm,Er,Y facilitate the alkylation of epoxides to give RCHR Cll20H (from 

CpTiClj induces decomposition of He SiNHNHSitte to N2, while tloOCl and (Me2Si 2MH or (Me2Si)2-iLi give a mixture of imide and 2 f1o complexes. 

For complete oxidation of 1 g of ammonia nitrogen, 4.57 g of oxygen is consumed. 

During nitrification hydrogen ions are released which react with hydrogen carbonates commonly present in waters. If the buffering capacity of water is insufficient, the pH value drops significantly. 

We now consider in turn the various forms in which nitrogen may occur in the environment, ammonia, nitrite, nitrate, cyanide and cyanate. 

Ammonia nitrogen occurs in the form of either non-dissociated ammonia, NH3, which is hydrated in water, or the cation NH. Relative representation of the two forms depends on pH. At a pH of approximately 9.3 the ratio of molar concentrations is approximately 1 1. 

Ammonia nitrogen is fairly toxic for fish, the toxicity being caused primarily by non-dissociated ammonia and not the NH ions. Non-toxic concentrations of NH3 for fish range from 0.01 to 0.04 mg 1.  

Like sulfur, nitrogen has stable compounds in a wide range of oxidation states and many of them are found in the atmosphere. Again, both gaseous and particulate forms exist as do a large number of water- 

Here we see a range of oxidation states from — 3 to -I- 5. The reduced forms are undoubtedly the most important gaseous bases in air, while the oxides tend to produce HNO3 as one of the two dominant strong atmospheric acids (H2SO4 is the other one). 

In particulate form, we find the condensed phase of some of these in the form of salts, as listed in Table 

A considerable number of sulfur-nitrogen compounds exist, and some of them have unusual properties. The most common compound of this type is S4N4, tetrasulfur tetranitride. The compound can be prepared by the following reaction  

It may also be prepared by the reaction of gaseous NH3 with an ether solution of S2C12  

Tetrasulfur tetranitride is thermochromic. The compound is nearly colorless at -190 °C, orange at 25 °C, and dark red at 100 °C. The compound can be purified by sublimation at 100 °C under reduced pressure. Although the compound is stable under a variety of conditions, explosions result when the compound is subjected to shock, which is not 

There is apparently significant interaction between the sulfur atoms. The experimental S-S distance is about 258 pm (that of an S-S single bond is about 210 pm), and the S-N distance is about 162 pm. The sum of the van der Waals radii for two sulfur atoms is about 370 pm, but the S-S distance where an N atom is linking them is only about 271 pm. Thus, an extended n electron system appears to be involved in the bonding. A sizable number of resonance structures can be drawn in which there are unshared pairs of electrons on the N and S atoms, but a molecular orbital approach that takes into account some delocalization of electrons over the entire structure provides a more satisfactory approach to the bonding. 

Tetrasulfur tetranitride undergoes a number of interesting reactions. Hydrolysis of the compound in basic solution produces NH3 as the nitrogen product in accord with nitrogen having the higher electronegativity  

Vegetables contain an average of 1-3% nitrogen compounds. Of this, 35-80% is protein, the rest is amino acids, peptides and other compounds. 

The protein fraction consists to a great extent of enzymes which may have either a beneficial or a detrimental effect on processing. They may contribute to the typical flavor or to formation of undesirable flavors, tissue softening and discoloration. Enzymes of all the main groups are present in vegetables  

In addition to protein-building amino acids, nonprotein amino acids occur in vegetables as well as in other plants. Tables 17.5 and 17.6 present data on the occurrence and stmcture of these amino acids. Information about their biosynthetic pathways is given below. 

The higher homologues of amino acids, such as homoserine, homomethionine and aminoadipic acid, are generally derived from a reaction sequence which corresponds to that of oxalacetate 

Number Common name Latin name Qass, order, family Consumed as 

The great structural diversity of nitrogen-containing compounds, ranging from imines and azo compounds to nitro compounds and amines, is connected to its diverse but characteristic photochemical reactivity (Table 6.15). The presence of a lone electron pair on nitrogen in chromophores containing an N=X bond (X=N, C) indicates that both the n,Jt and n,n excited states can be involved in the reactions. While E Z isomerization is a typical reaction for both imines and azo compounds (entry 1), the latter chromophores may additionally 

Photofragmentation is the principal primary process of excited aliphatic nitro compounds subsequently producing N02 and the corresponding radicals (entry 8), which may recombine to form nitrites. The excited nitroalkanes or nitroarenes can also be photoreduced in the presence of a hydrogen-atom donor (entry 9). 

Amines are generally good electron donors. They readily undergo photoinduced electron transfer (PET) processes, in which amine donates an electron to the reaction partner either in its ground or excited electronic state (entry 10). In contrast, electron-deficient, nitrogen-containing molecules, such as aromatic nitriles, may serve as electron acceptors (entry 11). Many organic metal complexes can also be involved in photochemically initiated redox reactions (Section 6.4.4). 

For example, owing to this last decomposition, the N204 concentration is 10 6 jig/m3, if the nitrogen dioxide level is 20 /rg/m3. Furthermore under normal atmospheric conditions N03 decomposes by photolysis or combines with NO. Thus Crutzen (1974) showed  

For these reasons, only nitrous oxide and NOv (x = 1 or 2) can be identified in practice in the air, if we disregard HNO, formed by the interaction of nitrogen dioxide and water vapour (see later). 

In addition to the above gases, ammonia (NH3) is also an important atmospheric trace substance. An essential characteristic of ammonia and NOx is that these trace gases transform in the air into ammonium and nitrate-containing aerosol particles. These particles are of importance for the control of many atmospheric processes (see Chapter 4). 

Besides the use of amino acids as a nitrogen source, flor yeast may use these compounds to balance the oxidation-reduction potential under conditions of restricted oxygen availability. This can be achieved by releasing amino acids into the medium to restore the intracellular redox balance by oxidation of excess NADH (Mauricio et ah, 2001a,b Moreno-Arribas and Polo, 2005 Valero et ah, 2003). 

Angeles Pozo-Bayon and M. Victoria Moreno-Arribas 

Details on the chemical and photochemical processes affecting nitrogen compounds in the middle atmosphere are given in the following sections Sections 5.5.1-5.5.3 deal with stratospheric nitrogen, while 5.5.4 and 5.5.5 focus on nitrogen compounds in the mesosphere and lower thermosphere. 

In the stratosphere, nitric oxide (NO) is produced mostly by dissociation of N2O by reaction with an excited oxygen atom in the (XD) 

The equation of continuity for nitrous oxide can thus be written  

Crutzen et al. (1975) noted that penetration of large amounts of protons into the middle atmosphere during solar proton events would also lead to an intense production of atomic nitrogen. These episodic events can produce enough nitrogen oxide to influence the ozone content, 

Several other gases released at the Earth s surface carry additional nitrogen into the middle atmosphere. This is the case of hydrogen cyanide (HCN) and methyl cyanide (CH3CN). In both cases, only limited observations are available and the global budget is not well quantified. The numbers quoted below represent, therefore, orders of magnitude only. 

Sodium nitrate (NaNOj) and potassium nitrate (KNO3) are formed by the decomposition of organic matter, with compounds of these metals present. In certain dry areas of the world, these saltpeters are found in quantity and are used as fertilizers. Other inorganic nitrogen compounds are nitric acid (HNO3), ammonia (NH3), the oxides (NO, NO2, N2O4, N2O), cyanides (CN ), etc. 

Ammonia (NH3) is the most important commercial compound of nitrogen. It is produced by the Haber Process. This process is the synthesis of ammonia by the water-gas reaction from hot coke, air, and steam. Natural gas (methane, CH4) is reacted with steam to produce carbon dioxide and hydrogen gas (H2) in a two-step 

In the presence of air, diphenylamines rearrange photochemically to carbazoles. Linschitz has shown that the reaction proceeds through diphenylamine triplet which slowly rearranges to a metastable intermediate. This intermediate reacts rapidly with oxygen to yield the carbazole.460 

Both the well-known photochromism453,454 and the phosphorescence454 of spiropyrans are enhanced by sensitizers such as benzo-phenone. Consequently the photochemical opening of these compounds to the deeply colored merocyanines can proceed via triplet states. 

Azobenzene readily undergoes both sensitized and direct cis-trans photoisomerization. However, the sensitized photostationary cis/trans ratios with high-energy sensitizers do not predict those obtained upon direct irradiation, indicating that much of the direct photoisomerization occurs from states other than the lowest triplet.455 As with stilbene, cyclization of the cis isomer apparently is a singlet-state reaction.456 

Cis-trans isomerization of a,JV-diphenylnitrones can be photosensitized but does not result upon direct irradiation.457 Instead, oxazirane formation occurs. Presumably, then, the nitrone - oxazirane photorearrangement proceeds from excited singlets. 

The well-known photorearrangement of urtAo-nitrobenzaldehyde to orfAo-nitrosobenzoic acid458 may well involve hydrogen abstraction as the initial photoprocess. Nitrobenzene is photoreduced in reactive solvents to iV-phenylhydroxylamine,459 and the intermolecular hydrogen abstraction apparently proceeds from the triplet state, since, when perfluoronaphthalene is present in the sample, the ESR spectrum of the PhN02H radical is replaced by the typical triplet ESR spectrum of the naphthalene.460 

we consider ammonia and its derivatives in the top 50 chemicals. We have completed a study of the number one inorganic chemical sulfuric acid and its derivatives and have also studied industrial gases from which ammonia is made. Ammonia is in the top 10 chemicals and some important ammonia derivatives are listed in the top 50 ammonium nitrate, nitric acid, urea, and ammonium sulfate. Most ammonia eventually ends up in fertilizers of one type or another. The manufacturing chemistry for these chemicals is outlined below. 

It might also be argued that ammonia and its derivatives are all petrochemicals since the hydrogen is derived from methane or natural gas. Many ammonia plants are near oil refineries. Urea even contains carbon and is considered an organic chemical. But because all these nitrogen 

T0022 Aero-Terra-Aqua Technologies Corporation, Aqua-Eix T0127 Blast Fracturing—General 

T0130 Bohn Biofilter Corporation, Bohn Off-Gas Treatment T0158 CH2M Hill, Phytoremediation-Based Systems T0178 Constructed Wetlands—General 

T0179 Constructed Wetlands for Acid Mine Drainage—General 

T0329 General Atomics, Supercritical Water Oxidation 

T0383 Huntington Environmental Systems, Econ-Abator Catalytic Oxidation System T0467 KSE, Inc., AIR-II Process 

Because the Sn2 nucleophilic substitution of uncharged amines with uncharged aMphatic organic halides involves a transition state that is more polar than that of the starting materials, such substitution reactions 

Comprehensive Organic Reactions in Aqueous Media, Second Edition, by Chao-Jun 

Reactions of ozone with nucleic acid constituents have not been much studied. Uracil (54) gave a variety of products including acyiated hydroxyhydantoins such as 92, whose structure was established by X-ray diffraction (Matsui et al., 1989). Ring-opened products were also identified a mechanism is shown in Equation 5.42. Caffeine (93) was attacked by ozone in the imidazole ring to give two prin- 

Pyridine is relatively stable to ozonolysis under nonradical conditions, giving the N-oxide as almost the only product (Andreozzi et al., 1991). The pyridinium cation is practically inert to ozonation. At higher pHs many products, including ring cleavage compounds, ammonia, and nitrate are produced (Equation 5.43). 

Quinoline was converted in good yield to nicotinic acid (Sturrock et al., 1960). With indoles, the pyrrole ring opens to give aniline derivatives, as in the formation of 2-aminobenzaldehyde and anthranilic acid from indole (Equation 5.44) (Jurs, 1966). 

Our knowledge of biogenic ammonia emission is still surprisingly small. Although there has been interest in ammonia research since 1800, and the recognition of its importance for plant growth and the changes in atmospheric ammonia have been 

The bacterial decomposition of animal excreta is the largest source of NH3 (Table 2.65). For example, colonies of wild animals, such as seabirds and seals, although they produce a small fraction of the global emission, have recently been recognized as hotspots of NH3 emission in remote areas with otherwise low NH3 emissions. Seabird colonies are found to represent the largest point sources of am- 

It is likely that natural ecosystems (forest, grassland) emit no or only small amounts of ammonia because normally there is a deficit of fixed nitrogen in landscapes. Reported emissions factors over forests span three orders of magnitude and are likely be influenced by re-emission of wet deposited ammonium. Older publications considerably overestimated emission by using simple models considering soil ammonium concentrations obtained from relative decomposition and nitrification rates, where Henry s law gives the equilibrium concentration of ammonia gas in the soil, and a simplified diffusion equation yields the flux to the atmosphere, for example, Dawson (1977) calculated it to be about 47 Tg N yr b 

Therefore, (dry) deposition exceeds emission, for example, in forests the soil may emit NH3 but it is up taken by the canopy, and hence remains within the ecosystem. This has been shown in the 1980s, when the European interest in ammonia motivated the first measurements of ammonia dry deposition to semi-natural ecosystems (e. g., Horvath 1983, Duyzer et al. 1987, Erisman and Wyers 1993, Sutton et al. 1993). While the earlier compensation point studies had identified plant stomata as the key exchange site, these European measurements noted large rates of dry deposition that could only be explained by the fact that most of the NH3 was deposited directly onto leaf surfaces. 

There is reason to assume that wildlife, as shown in Chapter 2.6.22 for domesticated animals, is the dominant natural source of NH3 (Table 2.32). A completely different pathway of emissions is the decay of urea or uric acid to ammonia in animal manure (from mammals or birds). This pathway may also lead to N2O formation. Emissions are much more pronounced for domestic animals, however, where manure is actually collected and kept liquid for longer periods of time, or other sites where animals live in a very dense populations (point emissions from bird breeding colonies on small islands, e. g., in the North Sea). 

This account follows the same scheme as last year s. Synthesis is discussed in sections according to reaction type and is followed by a brief consideration of miscellaneous reactions. The emphasis on synthetic studies continues but the increasing interest in the pharmacology of many of the novel systems is not discussed. Recent topics include the analgesic activity of l-azabicyclo[4,4,l]-undecanes, 3-azabicyclo[3,2,l]octanes, 3-azabicyclo[3,2,2]nonanes, 9-azabicyclo[3,3,l]nonanes, and substituted quinuclidines.  

Synthesis.—Mannich-type Reactions. The double Michael addition of amines to cyclohepta-2,6-dienone has been extended by the use of a series of optically active primary amines to the synthesis of chiral 8-azabicyclo-[3,2,l]octanes. Yields are typically ca. 70% circular dichroism studies show interesting effects. Perturbation of the n - rr transition must originate in the asymmetry of the nitrogen substituents which lie in the symmetry plane of the ring. The analysis of the tertiary amines is complicated by 

Arata and T. Kobayashi, Chem. and Pharm. Bull. (Japan), 1972, 20, 325. 

Yoneda, T. Ishichara, T. Kobayashi, K. Okumura, and M. Kojima, Chem. and 

lenaga, and Y. Hirata, Tetrahedron Letters, 1972, 335. 

NHj St 3500-3300 Of variable intensity, generally 2 sharp bands, Av = 65-75 At lower wavenumbers ( 3200) and broader if H-bonded. Free and H-lx)nded forms often simultaneously observed In primary aromatic amines additional combination band at 3200 

NH3 5 1600-1460 Medium, often more than one band weak in aliphatic amines 

Chemical shifts of amine protons lie aroimd 0.5-6 ppm depending on solvent, concentration, and hydrogen bonding. Those of ammonium protons are foimd between ca. 7 and 12 ppm. Neighboring H bond acceptors lead to deshielding in all cases. 

In acidic media (e.g., in trifluoroacetic add as solvent), the exchange of the ammonium protons is slowed down to such an extent that the vidnal coupling H-N+-C-H generally becomes observable. In other media, signals are usually broad owing to intermediate exchange rates. 

The signals of amine and especially of ammonium protons are often broadened additionally because the coupling is only partly eliminated by the 

Chemical Shifts and Coupling Constants of Amines and Ammonium Salts (d in ppm, J in Hz) 

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The collector contains an electrically-heated rubidium salt used as the thermionic source. During the elution of a molecule of a nitrogen compound, the nitrogen is ionized and the collection of these ions produces the signal. The detector is very sensitive but Its efficiency is variable subject to the type of nitrogen molecule, making quantification somewhat delicate. 

Crude oils contain nitrogen compounds in the form of basic substances such as quinoline, isoquinoline, and pyridine, or neutral materials such as pyrrole, indole, and carbazole. 

Concerning non-metallic compounds, the antiknocking properties of nitrogen compounds such that derivatives of aniline, indole and quinoline, and certain phenol derivatives have been mentioned. 

In the case of lubricant dispersants, the polar part is organic (amine, polyamine, heterocyclic nitrogen compounds, polyglycol). 

It has been tentatively suggested that one mechanism underlies the Willgerodt reaction and the Kindler modification of it. A labile intermediate is first formed which has a carbon—carbon bond in the side chain. The scheme is indicated below it postulates a series of steps involving the addition of ammonia or amine (R = H or alkyl), elimination of water, re addition and eUmination of ammonia or amine until the unsaturation appears at the end of the chain then an irreversible oxidation between sulphur and the nitrogen compound may occur to produce a thioamide. 

The imides, primaiy and secondary nitro compounds, oximes and sulphon amides of Solubility Group III are weakly acidic nitrogen compounds they cannot be titrated satisfactorily with a standard alkaU nor do they exhibit the reactions characteristic of phenols. The neutral nitrogen compounds of Solubility Group VII include tertiary nitro compounds amides (simple and substituted) derivatives of aldehydes and ketones (hydrazones, semlcarb-azones, ete.) nitriles nitroso, azo, hydrazo and other Intermediate reduction products of aromatic nitro compounds. All the above nitrogen compounds, and also the sulphonamides of Solubility Group VII, respond, with few exceptions, to the same classification reactions (reduction and hydrolysis) and hence will be considered together. 

Naphthalene hydrocarbons halogen compounds, nitrogen compounds. (1949.) hydroxy compounds. (l950.) oxo-compounds except quinones. (1950.) quinones. (1962.)... 

The key initiation step in cationic polymerization of alkenes is the formation of a carbocationic intermediate, which can then interact with excess monomer to start propagation. We studied in some detail the initiation of cationic polymerization under superacidic, stable ion conditions. Carbocations also play a key role, as I found not only in the acid-catalyzed polymerization of alkenes but also in the polycondensation of arenes as well as in the ring opening polymerization of cyclic ethers, sulfides, and nitrogen compounds. Superacidic oxidative condensation of alkanes can even be achieved, including that of methane, as can the co-condensation of alkanes and alkenes. 

Schofield, K. (1967). Hetero-Aromatic Nitrogen Compounds Pyrroles and Pyridines. London Burterworths. 

Alkaloids are basic nitrogen compounds of great structural complexity which occur in plants. About two dozen of different classes of alkaloids are covered in the "Specialist Periodical Reports of the English Chemical Society. 

Indoles are usually constructed from aromatic nitrogen compounds by formation of the pyrrole ring as has been the case for all of the synthetic methods discussed in the preceding chapters. Recently, methods for construction of the carbocyclic ring from pyrrole derivatives have received more attention. Scheme 8.1 illustrates some of the potential disconnections. In paths a and b, the syntheses involve construction of a mono-substituted pyrrole with a substituent at C2 or C3 which is capable of cyclization, usually by electrophilic substitution. Paths c and d involve Diels-Alder reactions of 2- or 3-vinyl-pyrroles. While such reactions lead to tetrahydro or dihydroindoles (the latter from acetylenic dienophiles) the adducts can be readily aromatized. Path e represents a category Iley cyclization based on 2 -I- 4 cycloadditions of pyrrole-2,3-quinodimcthane intermediates. 

The variation of Cp for crystalline thiazole between 145 and 175°K reveals a marked inflection that has been attributed to a gain in molecular freedom within the crystal lattice. The heat capacity of the liquid phase varies nearly linearly with temperature to 310°K, at which temperature it rises more rapidly. This thermal behavior, which is not uncommon for nitrogen compounds, has been attributed to weak intermolecular association. The remarkable agreement of the third-law ideal-gas entropy at... 

With heteroaromatic substrates it is possible to prepare, for example, thiazolyipyridines. It is noteworthy that basic solvents (e.g., heterocyclic nitrogen compounds) increase the yield of substitution by a cage effect (see Tables III-37 and III-38) (208). 

Many naturally occurring nitrogen compounds and many nitrogen containing drugs are bet ter known by common names than by their systematic names A few of these follow Wnte a struc tural formula for each one... 

These contracted names of heterocyclic nitrogen compounds are retained as alternatives for systematic names, sometimes with indicated hydrogen. In addition, names of 0x0 derivatives of fully saturated nitrogen heterocycles that systematically end in -idinone are often contracted to end in -idone when no ambiguity might result. For example. 

Chlorine Ammonia, acetylene, alcohols, alkanes, benzene, butadiene, carbon disulflde, dibutyl phthalate, ethers, fluorine, glycerol, hydrocarbons, hydrogen, sodium carbide, flnely divided metals, metal acetylides and carbides, nitrogen compounds, nonmetals, nonmetal hydrides, phosphorus compounds, polychlorobi-phenyl, silicones, steel, sulfldes, synthetic rubber, turpentine... 

Lead dioxide Aluminum carbide, hydrogen peroxide, hydrogen sulfide, hydroxylamine, ni-troalkanes, nitrogen compounds, nonmetal halides, peroxoformic acid, phosphorus, phosphorus trichloride, potassium, sulfur, sulfur dioxide, sulfides, tungsten, zirconium... 

Any one nucleotide, the basic building block of a nucleic acid, is derived from a molecule of phosphoric acid, a molecule of a sugar (either deoxyribose or ribose), and a molecule of one of five nitrogen compounds (bases) cytosine (C), thymine (T), adenine (A), guanine (G), uracil (U). 

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