Simplest Compounds

It is the simplest compound containing the -N = N- chromophore, but is of no practical importance since it lacks affinity for fibres. Normally it exists in the most stable trans form, but may be converted to a less stable, bright red as form, m.p. 71 -S C by ultra-violet irradiation. Cis to irans isomerization occurs rapidly on heating. 

The rocksalt stmcture is illustrated in figure Al.3.5. This stmcture represents one of the simplest compound stmctures. Numerous ionic crystals fonn in the rocksalt stmcture, such as sodium chloride (NaCl). The conventional unit cell of the rocksalt stmcture is cubic. There are eight atoms in the conventional cell. For the primitive unit cell, the lattice vectors are the same as FCC. The basis consists of two atoms one at the origin and one displaced by one-half the body diagonal of the conventional cell. 

The simplest compounds, -pyrroline and -piperideine,donotexistin the monomeric form. Schdpf et al. (29S) described two geometric isomers of J -piperideine trimer and called them a- and -tripiperideines (182). An equilibrium exists between A -piperideine and both trimers which, therefore, react as typical aldehyde ammonia. The trimer rearranges at pH 9-10 in an almost quantitative yield to isotripiperideine (183) which, in turn, is in equilibrium with tetrahydroanabasine (184) and -piperideine. 

Although the antithyroid activity of compounds incorporating an enolizable thioamide function was discussed earlier, this activity was in fact first found in the pyrimidine series. The simplest compound to show this activity, methylthiouracil (80) (shown in both enol and keto forms), is prepared quite simply by condensation of ethyl acetoacetate with thiourea.Further work in this series shows that better activity was obtained by incorporation of a lipophilic side chain. Preparation of the required dicarbonyl compound starts with acylation of the magnesium enolate of the unsyrametrically esterified malonate, 81, with butyryl chlo-... 

Replacement of the terminal nitrogen of the piperazine by carbon is said to enhance the antiemetic activity of the phenothiazines at the expense of the other pharmacologic effects. The simplest compound in this series, pipamazine (88), is prepared by alkylation of nipecotamide (87) with the chloropropyl phenothiazine (58). Preparation of the analogous sulfoxide begins with acetylation of the thiomethyl compound, 89 [prepared by a route... 

In another type of aromatic hydrocarbon, two or more benzene rings are fused together. Naphthalene is the simplest compound of this type. Fusion of three benzene rings gives two different isomers, anthracene and phenanthrene. 

There have a number of computational studies of hypothetical RMMR species [10-13, 40, 411. The simplest compounds are the hydrides HMMH. Some calculated structural parameters and energies of the linear and trans-bent metal-metal bonded forms of the hydrides are given in Table 1. It can be seen that in each case the frans-bent structure is lower in energy than the linear configuration. However, these structures represent stationary points on the potential energy surface, and are not the most stable forms. There also exist mono-bridged, vinylidene or doubly bridged isomers as shown in Fig. 2... 

Among the simplest compounds of this series are l-(2-deoxy-2-fluoro- -D-arabinofuranosyl)thymine (758, FMAU) and 1-(2-deoxy-2-fluoro-)S-D-arabinofuranosyl)-5-methylcytosine (749, FMAC). Later FIAU (757) and FMAU (758) were prepared in high yields (>95% the ratio of Plot an-omers being 7/1 and 4/1, respectively) by condensation using 743 and 2,4-bis(0-trimethylsilyl)-5-iodouracil (769), and 743 and 2,4-bis(0-trimethylsi-lyl)thymine (770), respectively. Likewise, 753, 757, 758, and 765 (this was described later) were prepared in high yields using pyrimidine derivatives... 

The simplest compounds which have been examined are the series CH3(CH2) CH3. The observed rate law is ... 

Special emphasis has been laid on structural studies of Cd compounds with dicarboxylic acids, because these combinations form coordination polymers of differing dimensionalities depending on the carboxylate component and on coligands coordinated to Cd. The simplest compound of this type, namely Cd oxalate CdC204, adopts a 3-D framework structure, with CdOe octahedra linked by oxalate groups.272 Further interesting structures containing Cd, oxalate and other components have been described recently.273,274... 

Several pyridine containing ligands of this type have been reported by Toftlund [2]. A combination of two aliphatic and four imine nitrogen functions seems to provide a ligand field at the crossover point. A versatile class of ligands of this type is based on aliphatic diamines substituted with four alkylpyridine groups. The simplest compound of this type is tetrakis(2-pyri-dylmethyl)-l,2-ethanediamine (tpen) (18). 

Figure 4.18 The reaction of alcohols with aldehydes (a) and ketones (b) to form hemiacetals and hemiketals. (c) The reaction between the alcohol on carbon 5 and the aldehyde of glucose forms two hemiacetals, ot-D-glucopyranose and P-D-glucopyranose (pyranose by comparison with pyran the simplest compound containing this six-membered ring).

Fischer then synthesized a number of di-and tripeptides and showed that their properties were identical to those of the di-and tripeptides which could be obtained after partial protein hydrolysis. A peptide containing 18 amino acid residues was eventually synthesized. Molecules containing peptide bonds were found to give a characteristic pink to purple color in the presence of dilute alkaline copper sulfate. The simplest compound which does this is biuret, formed when urea is heated at 150-160 °C ... 

The simplest compounds to consider here are ammonia and water. It is apparent from the above electronic configurations that nitrogen will be able to bond to three hydrogen atoms, whereas oxygen can only bond to two. Both compounds share part of the tetrahedral shape we saw with 5/ -hybridized carbon. Those orbitals not involved in bonding already have their full complement of electrons, and these occupy the remaining part of the tetrahedral array (Figure 2.21). These electrons are not inert, but play a major role in chemical reactions we refer to them as lone pair electrons. 

A hydrocarbon with a triple bond between carbons is an alkyne, and the simplest compound in this class is acetylene, C2H2, as shown in Figure 6-8. 

In order to exploit the cycloaddition reactions of 2-vinylbenzofurans for natural product synthesis, the reactions of (E)-2-()S-methoxyvinyI)benzo-furans have been examined. The simplest compound (139, Scheme 36) on reaction with dimethyl acetylenedicarboxylate in boiling toluene gave a mixture of products. The major adduct was not the one expected but was its conjugation product 140. The diene system in 140 is able to react with... 

The 100 Most Important Chemical Compounds focuses on 100 compounds, but references several hundred compounds. Structures and formula for compounds other than the 100 are included in the entries and listed in the index. Repetition of information was kept to a minimum by including representative compounds or the simplest compound in a chemical family and highlighting chemical properties that distinguish chemical groups. For example, there are entries for methane, ethane, butane, and octane but other alkanes such as pentane, hexane, and heptane are not included. Most personal names in the book include years of birth and... 

---