Aliphatic Examples

The aUcoxylamines have a N—O—C substrucmre and may be considered O-substituted hydroxylamine ethers. The simplest example of these species is MeONH2 with a gas phase enthalpy of formation of —25.1 kJmol which was discussed in a previous section. Consider now the perfluorinated species (CF3)2N0CF2CF20N(CF3)2 and its synthesis shown in equation 9. 

Additionally, we posit thermoneutrality for equation 11 in order to to derive the enthalpy of formation of the bis hydrocarbon hydroxylamine ether of —73 kJmol .  

The calculated value for the perfluoro species in equation 10 is —3269 kJmol The literature value is —3283 80 kJmol. The agreement is almost too good to be true  

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A number of secondary high explosives containing both nitramine and nitrate ester functionality have been reported. Aliphatic examples include A-nitrodiethanolamine dinitrate (DINA) (110), prepared from the nitration of diethanolamine with nitric acid-acetic anhydride in the presence of zinc chloride,and A,A -dinitro-A,A -bis(2-hydroxyethyl)oxamide dinitrate (NENO) (111), prepared from the mixed acid nitration of A,lV -bis(2-hydroxyethyl) oxamide . 

The self-condensation of 2-aminobenzaldehyde in the presence of suitable metal ions to form the cyclic tetramer (1), and sometimes the trimer (2), is the best-known example of this reaction type (Scheme 2). The cyclization of the / -amino ketone complex (5) provides an aliphatic example... 

Recently it has been shown by Chikashita et al. that hydride transfer is possible from the benzimida-zoline (21) to an acyl chloride, giving the corresponding aldehyde and benzimidazolium salt (22 equation 1) The reaction is most effective in the presence of 1 mol equiv. of acetic acid. Although it has only been used for a few aldehydes, it is successful with aromatic and aliphatic examples (e.g. p-nit-robenzaldehyde, 82% g.c. yield cyclohexanecarbaldehyde, 80% g.c. yield) and may have substantial potential. Another new method is the treatment of aroyl chlorides with dialkylzinc reagents in the presence of catalytic palladium complexes. However, the applicability would seem to be limited by the rather low yields. 

Three reactions can result from the reduction of halogenated aliphatics, examples of which are given in Table 7.3. A hydrogenolysis reaction results in the replace-... 

Fisher s oxazole formation occurs by the condensation of cyanohydrins with aldehydes in the presence of HCl in dry ethereal solution. The cyanohydrins and aldehydes used are usually aromatic in nature, although there are aliphatic examples that have been reported. There has been little study of the reaction mechanism such as that shown by Ingham and Comforth in the early nineteenth century the reaction details have also been published by others. " The first step of the mechanism is the addition of HCl to the cyanohydrin to from an iminochloride intermediate 2. This intermediate then reacts with the aldehyde, which is followed by water loss to give a chloro-oxazoline intermediate 4. Isomerization of two protons occurs, followed by the loss of an HCl molecule to form the 2,5-diaryloxazole end product. 

The value for allylamine raises the question of what would be the effect of moving the doublebond one place towards the nitrogen atom. Although simple aliphatic examples have not been measured, the phenomenon can be examined in the comparable tetrahydropyridines and dihydropyrroles (Adams and Mahan, 1942). 

Some oxygen heterocycles are more basic than the aliphatic examples in Table 8.8, because extra resonance is possible in the (heterocyclic) cations. Thus 4-pyrone and anthocyanidin have pKg values of +0 3 and 4 0 respectively. 

Photocyclization of 5,5-dimethyl-3-hexen-2-one provides an aliphatic example, with the added twist that the a, 3-unsaturated ketone undergoes photoinduced cis/trans equilibration, which allows the cis-isomer to undergo 8-hydrogen abstraction." ... 

We cite isomerization of Cs-Ce paraffinic cuts, aliphatic alkylation making isoparaffinic gasoline from C3-C5 olefins and isobutane, and etherification of C4-C5 olefins with the C1-C2 alcohols. This type of refinery can need more hydrogen than is available from naphtha reforming. Flexibility is greatly improved over the simple conventional refinery. Nonetheless some products are not eliminated, for example, the heavy fuel of marginal quality, and the conversion product qualities may not be adequate, even after severe treatment, to meet certain specifications such as the gasoline octane number, diesel cetane number, and allowable levels of certain components. 

The reaction of an atom with a diatomic molecule is the prototype of a chemical reaction. As the dynamics of a number of atom-diatom reactions are being understood in detail, attention is now being turned to the study of the dynamics of reactions involving larger molecules. The reaction of Cl atoms with small aliphatic hydrocarbons is an example of the type of polyatomic reactions which are now being studied [M, 72, 73]. 

There are similar analogues to other aliphatic hydrocarbons, for example HjN BHj, which is isoelectronic with ethene, and a most interesting compound called borazine, B3N3H6, which possesses physical properties remarkably like those of the aromatic analogue ... 

Thus, to name just a few examples, a nucleophilic aliphatic substitution such as the reaction of the bromide 3.5 with sodium iodide (Figure 3-21a) can lead to a range of stereochemical products, from a l l mbrture of 3.6 and 3.7 (racemization) to only 3.7 (inversion) depending on the groups a, b, and c that are bonded to the central carbon atom. The ring closure of the 1,3-butadiene, 3.8, to cyclobutene... 

After return to the Commander window, the reaction retrieval may be executed separately 629 Dicls-Aldcr reactions between aliphatic dienes and cyclic dicno-pliiles are found. This partial result can be narrowed down by restricting tlie reaction conditions by means of the fact editor, The search field codes for the yield and the temperature can be found to be RX.NYD and RX.T, respectively, either by browsing the database structure or by applying the Find option, as described in the first example. To ensure that the retrieved reaction conditions belong to the same experiment, both search terms must be connected by means of the PROXIMITY operator. Before the retrieval is started, the option "Refine results in... 

Example For the AMEER force field, a carbonyl C-0 bond has an eqnilibrniin bond length of 1.229 A and a force con stant of 570 kcal/mol A-. The potential for an aliphatic C-C bond has a in ini-mum at 1.526 A. I hc slope of the latter poten tial is less steep a C... 

Consequently traces of these unstable peroxides are present in samples of all the lower aliphatic ethers unless the samples have been freshly distilled. If these ethers when being distilled are heated on, for example, an electric heater, the final residue of peroxide may become sufficiently hot to explode violently. The use of a water-bath for heating, as described above, decreases considerably both the risk of the ether catching fire and of the peroxide exploding. 

It should be noted that aliphatic compounds (except the paraffins) are usually oxidised by concentrated nitric acid, whereas aromatic compounds (including the hydrocarbons) are usually nitrated by the concentrated acid (in the presence of sulphuric acid) and oxidised by the dilute acid. As an example of the latter, benzaldehyde, CjHsCHO, when treated with concentrated nitric acid gives ffi-nitrobenzaldehyde, N02CgH4CH0, but with dilute nitric acid gives benzoic acid, CgHgCOOH. 

When an aromatic compound having an aliphatic side chain is subjected to oxidation, fission of the side chain occurs between the first and second carbon atoms from the benzene ring, the first carbon atom thus becoming part of a carboxyl ( -COOH) group. For example ... 

TTie true ketones, in which the >CO group is in the side chain, the most common examples being acetophenone or methyl phenyl ketone, C HjCOCH, and benzophenone or diphenyl ketone, C HjCOC(Hj. These ketones are usually prepared by a modification of the Friedel-Crafts reaction, an aromatic hydrocarbon being treated with an acyl chloride (either aliphatic or aromatic) in the presence of aluminium chloride. Thus benzene reacts with acetyl chloride... 

The dichlorides of aliphatic glycols are obtained by reaction with thionyl chloride in the presence of a small quantity of pyridine, for example ... 

The chlorides of secondary aliphatic alcohols are prepared by method 1, for example —... 

The chlorides of tertiary aliphatic alcohols are readily prepared by the action of concentrated hydrochloric acid upon the alcohol at the laboratory temperature, for example ... 

Aliphatic nitro compounds. These are isomeric with the alkyl nitrites and may be prepared from the alkyl halide and silver nitrite, for example C,H,aBr + AgNOj — C Hj NO + AgBr... 

With higher aliphatic acids, RCOOH, keten yields first a mixed anhydride CH3COOCOR, which can be distilled under reduced pressure by slow distillation at atmospheric pressure the mixed anhydride undergoes rearrangement into the anhydride of the higher fatty acid and acetic acid, for example ... 

Examples of the preparation of simple aliphatic esters by Fischer and Speier s method in which an excess of acid is employed are —... 

The reaction is applicable to the preparation of amines from amides of aliphatic aromatic, aryl-aliphatic and heterocyclic acids. A further example is given in Section IV,170 in connexion with the preparation of anthranilic acid from phthal-imide. It may be mentioned that for aliphatic monoamides containing more than eight carbon atoms aqueous alkaline hypohalite gives poor yields of the amines. Good results are obtained by treatment of the amide (C > 8) in methanol with sodium methoxide and bromine, followed by hydrolysis of the resulting N-alkyl methyl carbamate ... 

From nitriles by Stephen s reaction (see under Aliphatic Aldehydes and Section 111,64), for example ... 

Aromatic primary alcohols diflfer from aliphatic primary alcohols in that they react with concentrated hydrochloric acid in the cold to yield the corresponding chlorides, for example ... 

Aromatic aldehydes, and also aliphatic aldehydes containing no a-hydrogen atom, undergo the Cannizzaro reaction (see Section IV,123) when treated with aqueous alkali, for example ... 

Similar ligand-ligand interactions have been reported for a large number of ternary -amino acid complexes, built up of two different amino acid.s. A compilation of 72 examples is presented in reference 39. The extra stabilisation due to ligand-ligand interactions in these complexes depends on the character of the amino-acid side chains and amounts to 0.34 - 0.57 kJ/mole for combinations of aromatic and aliphatic side chains and 0.11 - 6.3 kJ/mole when arene - arene interactions are possible. ... 

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