Experimental detail

The experimental setup for measuring the heat release and the specific heat consists of a calorimeter on which the sample is mounted. The samples were cooled from 80 K to 0.050 K in about (5-8) x 10 s. The calorimeter is attached to a holder through a thermal resistance or a superconducting heat switch made of an A1 strip. The holder is screwed to the mixing chamber of a top loading dilution refrigerator. 

Two sample holders were used, one from plastic and a second from Teflon. The first one showed a heat release approximately proportional to r whereas for the second one no heat release was measured in agreement with previous measurements [2]. 

The specific heat of both polymers was measured with the heat pulse technique in semiadiabatic fashion. The thermal conductivity was measured with a top loading He refngerator using the standard procedure. The acoustic properties, sound velocity and attenuation, were measured with the vibrating reed technique [16] in the frequency range (0.2 3) kHz. 

Both polymers were prepared following standard procedures. The PMMA sample had additionally 10 mol% of tetra-4-tert.butyl-phthalocyamin (dye molecule) because it was used in an early optical bole burning experiment [15]. For the specific heat and heat release measurements the mass and density of the PMMA sample were determined as 11.97 g and 1.15 g/cm, respectively. We have measured two PS samples prepared from different batches. The densities of these samples were 1.05 g/cm, and the masses 11.4 g (sample PSl) and 38.0 g (sample PS2). 

Unless noted otherwise, the experimental work in this chapter involved a model flexible slabstock PU foam formulation [39] at the instant of mixing (see below)  

For simplicity s sake, chemical reactions were avoided. This was accomplished by substituting toluene for toluene diisocyanate (TDI) in the formulation. This formulation had a nominal viscosity of about 0.8 Pa-s. 

The following experimental variables were addressed during the design and construction of the interferometer  

The two nearly plane-parallel surfaces of the film constitute a Fizeau interferometer which produces interference fringes in the reflected light [40]. The fringes are lines of constant film thickness. Film drainage data were acquired by generating monochromatic light by means of an interference filter (k= 505 nm) or with a FieNe laser X= 632.8 nm). 

As previously pointed out, the 33S NMR signal is often difficult to detect. Acquiring 33S spectra with an acceptable S/N may require from a few minutes to several days, depending on the symmetry of the sulphur electronic environment and molecular size. Therefore, a suitable choice of acquisition parameters and other experimental conditions (e.g. solvent and concentration in liquid phase, density in gas phase, temperature and so on) is particularly important. In addition, signal-processing methodologies can be critical for extracting all the information contained in a FID, especially when the S/N is not satisfactory. 

Some practical aspects of 33S NMR spectroscopy are outlined in the following section. For a deeper discussion, the reader can refer to the literature.13 

Other experimental factors that must be considered attentively are temperature, nature of the solvent and solution concentration. A substantial improvement in S/N and sensitivity can be achieved by increasing the temperature of acquisition. Indeed, raising the temperature can lead to a decrease in the line width, due to faster molecular tumbling, and to an increase in the solubility or miscibility of the solute, if necessary. Low-viscosity solvents should be preferred, since molecular tumbling depends on the medium viscosity. 

In acquiring 33S FT NMR spectra, further problems arise from the presence of spurious transitory signals at the beginning of the FID that cause baseline rolling in the FT spectrum. These baseline distortions prevent the sufficiently precise measurement of NMR parameters and sometimes the unambiguous identification of resonances. This problem is common to all fast-relaxing nuclei with low 

The effects of ring-down due to any of the previously reported causes can be reduced in three different ways (i) by acquiring spectra at high magnetic fields (ii) by using suitable pulse sequences and (iii) by introducing a delay time between the end of the pulse and the beginning of the acquisition. 

In the chapters that follow, a considerable part is given to the results of investigations performed by the author ofthis book and his coworkers. As a rule, traditional experimental methods were used nevertheless, some details are noteworthy. 

Electrochemistry of Metal Complexes Applications from Electroplating to Oxide Layer Formation, First Edition. Arvydas Survila. 

The active element of the electrochemical quartz crystal microbalance (EQCM) was a gold-coated quartz crystal whose oscillation frequency was equal to 5 or 6 MHz. It was plated in a similar way, but the metal coatings were thinner (0.2-0.4pm). The constant relating the variations in quartz crystal mass with its oscillation frequency was determined by special calibration using EQCM data obtained in acid CuSO solutions at a controlled current density. 

prepared electrodes were rinsed with water, immediately immersed into the solution to be tested, and kept for the controlled time t under open-circuit conditions. Until then, a pure argon stream was passed through solutions for 0.5 h. 

All experiments were carried out at 20 C temperature, unless otherwise noted. 

Degussa P25 grade Ti02 was used as catalyst for all the experiments. The crystalline product is nonporous primarily in the anatase form (70 30 ana-tase to rutile) and is used without further treatment. It has a BET surface area of (5.5 + 1.5) x lO m kg and crystallite sizes of 30 run in 0.1-0.3 0,m diameter aggregates. 

For better catalyst fixation and its durability, the glass surface of the tubes and the lamps on which titania was deposited were roughened by sand blasting. This makes the catalyst surface imeven but increases the strength and amoimt of catalyst per unit area that could be deposited. It is known that adherence of Ti02 on quartz is poor than on Pyrex. However, when the 

At the start of every experiment, the reactor was rinsed with Milli-Q water before zero-setting the analytical instrument. The reactor was then filled with the dye solution and it was ensured that no air bubbles remained in the system. The change in the dye concentration was continuously recorded. 

At steady state, about 21 counter rotating vortex pairs were observed and the dimension of the each counter rotating pair was almost twice the gap of the armular space. It was also observed that 

In Table 3, reactor specifications and experimental conditions used and efficiency obtained for the different reactors are compared. A more practical engineering definition for efficiency is used instead of more scientific quantum efficiency. The efficiency of each of the reactors, expressed in terms of 50% pollufanf converted per unit time per unit reactor volume per unit electrical power consumed, is compared for the same model component (Orange II dye) and same initial concentration 

Electrolytic-grade nickel (99.98 mass % Ni) was used in the form of polished plates 3x9x14 mm3. Their final treatment involved electrolytic polishing, both to remove the surface contaminations and to reduce mechanical stresses. 

The plates were mounted into graphite crucibles, 11 mm inner diameter, and heated to about 350°C under a previously dried low-melting flux 

A continuous, coherent intermetallic layer, 1,5 0.5 pm thick, was found to form during the specimen preparation. Hence, this technique ensured an intimate contact between the nickel and bismuth phases, so that the reaction started simultaneously anywhere along the entire Ni-Bi interface. Therefore, both intermetallics, NiBi and NiBi3, had favourable nucleation conditions. 

Each bimetallic specimen thus obtained was cut into two pieces using an electric-spark machine. The surface of the Ni-Bi couples was first ground mechanically and then polished electrolytically using an Elypovist  

The Ni-Bi couples were annealed in sealed glass ampoules, filled with high-purity helium (0.25 atm), at 150, 200 and 250°C for 1 to 300 h. Each couple was annealed successively a few times. After each anneal, the specimen surface was examined in the as-received conditions and after mechanical and/or electrolytic polishing. 

The basic components include a Nd YAG pulsed laser system which is coaxial with a He Ne pilot laser and visible light optical system. The latter system enables the analytical area of interest to be located. The TOF-MS has a flight path of 2m in length, with an ion detection system that includes an electron multiplier detector, a multichannel transient recorder, together with a computer acquisition and data processing system. 

The analytical area of interest is positioned in the focal spot of the He Ne laser beam, the transient recorder is armed to record, and the Nd YAG laser is fired. This laser pulse of between 5 and 15 ns duration produces a packet of ions that is accelerated from the sample surface and injected into the TOF-MS. All the 

ION EXTRACTION OPTICS AND LIGHT OBJECTIVE LENS (REFLECTION MODE) 

In a transmission mode instrument, the Nd YAG laser beam is focussed on the back side surface of thin samples ( 1 pm thick). A spot diameter of 0.5 pm is possible, and commercial instruments of this configuration have been used primarily for biomedical and particle analysis applications. 

FIGURE 8.11 Simplified diagram of the gradient ultrahigh pressure instalment. 

The sequential recording of electron spectra for small changes in the photon energy finally leads to the desired complete data set for electron intensities I = I(hv, kin). The data can be mapped in three dimensions, or in two dimensions if a grey scale is used for the intensities (black and white for extreme values of 

Within the energy ranges covered in Fig. 5.1 the dominant photoprocesses are 4d excitation/ionization with subsequent autoionization/Auger decay, and the 

Hitherto the discussion of Fig. 5.2 has neglected the possibility of non-radiative decay following 4d shell excitation/ionization. These processes are explained with the help of Fig. 5.2(h) which also reproduces the photoelectron emission discussed above, because both photo- and autoionization/Auger electrons will finally yield the observed pattern of electron emission. (In this context it should be noted that in general such direct photoionization and non-radiative decay processes will interfere (see below).) As can be inferred from Fig. 5.2(h), two distinct features arise from non-radiative decay of 4d excitation/ionization. First, 4d - n/ resonance excitation, indicated on the photon energy scale on the left-hand side, populates certain outer-shell satellites, the so-called resonance Auger transitions (see below), via autoionization decay. An example of special interest in the present context is given by 

Restricting the discussion again to 5s25p4 electron configurations of the final state, one has two groups of Auger transitions classified as 

After this schematic discussion of possible processes around the 4d ionization shell in xenon, Fig. 5.2(h) can be compared with the experimental results shown in Fig. 5.1. The main structures can be related to 4d, photoexcitation/ionization, and autoionization/Auger decay to 5s25p4fa electron configurations can be identified in the energy regions of overlap. 

The scattering data were analyzed by a function I(q) similar to that proposed by Formisano and Teixeira [101, 102], which is composed of additive contributions accounting for the scattering of the silica matrix and an ad- 

The term Ip/q in Eq. (4.144) accounts for the Porod scattering [104], which is caused by the granular. structure of the CPG-10 and the resulting contrast between the matrix and the liquid in the interstitial space. The term /bg accounts for the noncoherent scattering background resulting from the nondeuterated organic liquid. 

At high temperatures (i.e., in the one-phase region of the liquid mixture) the scattering of the pore liquid is described by an Omstein-Zernike term, I q) oc (1 + a correlation length characterizing the compo- 

sis of the SANS data [106] reveals that the Ornstein-Zernike term can be neglected at low temperatures, whereas the Debye term can be neglected at high temperatures. Details of the data analysis based on the expression given in Eq. (4.144) are presented in Ref. 106. The mean-field model described in Section 4.6.2 cannot account for fluctuation-induced effects. In the current work, we focus on the effects caused by confinement and 

Spectral properties of AIN, including absorption and luminescence in the visible and UV range, actual for practical application are determined by a wide band gap ( g = 6.2 eV) of the material and presence of lattice defects and impurities. In the form of ceramics, AIN maintains almost all properties of single crystals, except that if no special measures are undertaken ceramics are not transparent. Translucent AIN ceramics can be produced by choosing the appropriate concentration and type of sintering aid, such as CaFj [25] or Ca3Al20g [26]. 

AIN ceramics reveals luminescence under exposure of radiation of different types - a and p beams, y. X-rays, and UV light. In this paper, we will pay attention mostly to properties of luminescence produced by UV light irradiation, as well as stop briefly on luminescence properties produced by ionizing radiation, which potentially can be used in dosimetry. The experimental results mentioned in this chapter are described in detail in our previous works [27—41]. 

Luminescent properties were studied for AIN ceramics produced according to the procedures described above in this chapter. For luminescence measurements, we have chosen the samples sintered at 1700 C during 300 min from AIN plasma-produced fine powder with 5wt% admixture of Y2O3 powder. The resultant ceramics is opaque and has a light gray color. For the sake of convenience, ceramic ingots with 10 mm 0 were cut into 1 mm thick tablets. 

Luminescence of AIN ceramics was studied (i) during irradiation process, in the case of UV fight irradiation this type of luminescence is called photoluminescence (PL), (fi) after ceasing of irradiation - in the form of afterglow (AGL), (iii) during heating of the previously irradiated sample - in the form of thermoluminescence (TL), (iv) during illumination of the previously irradiated sample - in the form of optically stimulated luminescence (OSL). 

The following experimental equipment was used for the studies of UV-radiation-induced luminescence processes. UV irradiation was provided either 

A calibration problem for Doppler tuning arises from the poorly defined absolute beam energy, due to the potential of the plasma surface. Several techniques have been applied to circumvent this problem (i) A calibrated laser-frequency scan is used to compensate a certain Doppler detuning of the resonance, and with known Ai and AD the unknown beam energy eU—in first-order approximation 

This can be checked independently by the remeasurement of a well-known and sufficiently large atomic energy difference, (iv) Mth calibrated laser-frequency tuning for parallel and antiparallel beams the constant beam energy essentially cancels out in the averaging of the measured frequency intervals. For example, the isotope shift 8p between the two isotopes A and A is given to first order by the expression 

As the spectroscopy on ions often involves high-lying metastable states, the metastable population in the ion source is a crucial point It is difficult to measure, and the estimates for various ion sources scatter between 10 and A more quantitative systematic investigation of the best 

The commonly used fluorescence detection has to cope with a considerable background from scattered laser light. In fact, most experiments avoid detecting on the excitation wavelength and use the decay branch to a third state, selected by optical filters. If such a decay is weak or does not exist, the background has to be rejected by careful shaping of the laser beam 

As mentioned before there are two important parameters that are required for the fabrication of superhydrophobic smfaces, namely, surface roughness and low siuface energy. In order to roughen metallic surfaces in a controlled manner, particularly stainless steel smfaces, the laser ablation method has been used in this work. The stainless steel substrates were mounted on a precise, computer-controlled translation stage capable of moving in front of a fixed laser beam. 

The effects of laser parameters such as laser power (fluence), number of laser pulses induced to the surface (scanning speed) and laser beam overlap on the smface structure and wettability were examined. The various fabricated substrates were analyzed in terms of their geometrical characteristics. After laser irradiation, certain samples were subjected to silani-zation in order to reduce their surface energy. These surfaces were also analyzed in terms of their geometrical characteristics in order to determine the influence of silanization. 

All experiments were done using stainless steel substrate. Due to the dependency of laser ablation method on the thermo-physical properties of the substrate, the morphology of surface for other metallic surfaces is expected to be different. 

Synthesis of Pent-4-enyl 2,3,4-tri-0-benzoyl-6-0-(2,3,4,6-tetra-0-benzyl-a-D-glu-copyranosyl)-a-D-glucopyranoside (3) [32], 

Notes and discussion. Although it had been well documented that protecting groups could influence the reactivity of glycosyl donors [1, 2], Fraser-Reid et al. demonstrated for the first time that an activated pentenyl donor la could be selectively activated in the presence of a second, deactivated, pentenyl acceptor 2a. The disaccharide 3a thus obtained could be further activated to allow formation of a glycopeptide [32]. 

Dry diethyl ether (30 ml distilled from sodium benzophenone ketyl) 

10% aqueous sodium bicarbonate solution (100 ml) Magnesium sulfate 

Round bottomed flask (100 ml) with stirrer bar and septum (pressure balance ) Magnetic stirrer Silver foil Syringes 

In order to evaluate the photoconductivity energy threshold and the quantum yield the spectral distribution of the light entering the liquid must be known. The relative spectral distribution of VUV-light can be obtained by recording the fluorescence of sodium salicylate deposited on the inside of the entrance window of the conductivity cell. The relative quantum yield of the fluorescence emission spectrum with a peak at 420 nm varies less than 20%, with the incident wavelength between 100 and 160 nm (Samson, 1967). The fluorescence is measured with a photomultiplier. For the determination of the quantum flux, the conductivity cell is filled with a few tens mbar of NO for which the absolute quantum yield for photoionization has been reported (Watanabe et al., 1967). Measurement of the photoelectron emission yield of a gold layer can also be employed (Krolikowski and Spicer, 1970). 

various values between 1.5 and 3 have been proposed in the literature (Pope and Swenberg, 1982). 

It is important to note that spinodal dewetting - does not imply that the surface instability and consequent dewetting can occur only in the form of a bicontinuous structure composed of liquid ridges or hills and valleys. The thin-film experiments presented here demonstrate that a rich variety of morphological patterns can evolve. 

Probably the main difficulties associated with in situ X-ray techniques are reconciling the cell requirements of the electrochemistry with a suitable configuration for the X-ray technique and detecting the inevitably small signals. This is true of both diffraction and absorption measurements. This section will be concerned with how these problems are overcome and how the relevant experiments are performed. 

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Xie X and Simon J D 1989 Picosecond time-resolved circular dichroism spectroscopy experimental details and applications Rev. Sol. Instrum. 60 2614-27... 

Give brief experimental details to indicate how you could prepare in the laboratory a sample of either tin(IV) chloride or tin(IV) iodide. How far does the chemistry of the oxides and chlorides of carbon support the statement that the head element of a group in the Periodic Table is not typical of that group (JMB, A)... 

The ethereal extracts are then united, dried with a suitable drying agent and filtered. The filtrate is then cautiously distilled, the ether being first distilled and finally the organic compound if volatile if the compound is solid, the crude residue is purified by recrystallisation. Very great care must be taken on all occasions when ether is distilled because of the risk of fire or of an explosion full experimental details for this operation are given, both on p. 8o (Preparation of Ether) and on p. 164 (Pre-... 

An important application of the critical solution temperature is to the determination of the water content in such substances as methyl and ethyl alcohols. Here the system is usually the alcohol and a hydro carbon, such as -hexane or dicyclohexyl the water is, of course, insoluble in the hydrocarbon. Thus, the methyl alcohol - cyclohexane system has a C.S.T. of 45 -5° and even 0 01 per cent, of water produces a rise of 0-15° in the C.S.T. The experimental details are given below. 

Full experimental details for the determination of melting and boiling points are given in Sections 11,10 and 11,11 respectively. The Tables II, 9, A and II, 9, B list suitable substances for the cabbration of thermometers by melting point or boiling point determinations respectively. Substances which are bracketed are alternative to each other. It need hardly be emphasised that only compounds of the highest purity should be employed. 

The experimental details for recrystallisation from mixed solvents (or solvent pairs) will be evident from the account already given the best proportions of the two solvents are determined by preliminary small-scale experiments. 

If preferred, the following alternative procedure may be adopted. The absolute alcohol is placed in a 1 5 or 2 litre three-necked flask equipped with a double surface reflux condenser and a mercury-sealed mechanical stirrqr the third neck is closed with a dry stopper. The sodium is introduced and, when it has reacted completely, the ester is added and the mixture is gently refluxed for 2 hours. The reflux condenser is then rapidly disconnected and arranged for downward distillation with the aid of a short still head or knee tube. The other experimental details are as above except that the mixture is stirred during the distillation bumping is thus reduced to a minimum. 

Benzene. The analytical reagent grade benzene is satisfactory for most purposes if required dry, it is first treated with anhydrous calcium chloride, filtered, and then placed over sodium wire (for experimental details, see under Diethyl ether, 1). 

The student should fiirst read Sections I,l-I,3 which deal with the theory of the subject, and Section 11,12 in which the experimental details are given. 

The preparation may be adapted from the experimental details given for Diethyl Adipate (Section 111,99). Another method is described in Section 111,100. 

Experimental details devised for elementary students Method A) and for advanced students (Method B) will be given for this preparation. 

Propionaldehyde. Use 34 g. (42-6 ml.) of n propyl alcohol, and a solution containing 56 g. of sodium chromate dihydrate, 300 ml. of water and 40 ml. of concentrated sulphuric acid. The experimental details are identical with those for n-butyraldehyde, except that the addition of the dichromate solution occupies 20 minutes, the temperature at the top of the column is not allowed to rise above 70-75°, and during the subsequent heating for 15 minutes the liquid passing over below 80° is collected the receiver must be cooled in ice. The yield of propionaldehyde, b.p. 47-50°, is 12 g. 

Semicarbazones. For experimental details, see under Aliphatic Ketones, Section 111,74,2. 

In order to obtain practice in the preparation of the above derivatives, experimental details for a few typical examples will be given. 

Experimental details for the preparation of oximes, phenylhydrazones and p-nitrophenylhydrazones will be found under Aromatic Aldehydes, Section IV,135,4-6. 

Drop 1 g. of sodium into 10 ml. of ethyl alcohol in a small flask provided with a small water condenser heat the mixture until all the sodium has dissolved. Cool, and add 1 g. of the ester and 0-5 ml. of water. Frequently the sodium salt of the acid will be deposited either at once or after boiling for a few minutes. If this occurs, filter oflF the solid at once, wash it with a little absolute ethyl alcohol (or absolute methylated spirit), and convert it into the p-bromophenacyl ester, p-nitro-benzyl ester or S-benzyl-tso-thiuronium salt (for experimental details, see Section 111,85). If no solid separates, continue the boiling for 30-60 minutes, boil oflF the alcohol, allow to cool, render the product just neutral to phenolphthalein with dilute sulphuric or hydrochloric acid, convert the sodium salt present in solution into a crystalline derivative (Section 111,85), and determine its melting point. 

Experimental details for the preparation of derivatives with benzoyl chloride and with 3-nitrophthalic anhydride are given in Section IV,100,2 and 7. 

The experimental details describe the use of a free secondary amine for the preparation of a nitrosainine. Identical results are, of course, obtained by employing solid diethylamine hydrochloride. 

Derivatives of higher melting point may be obtained withp-nitrobenzoyl chloride the experimental details are similar to those given above for benzoyl chloride. 3 5-Dinitrobenzoyl chloride (Section 111,27,7) may also be used glycerol gives unsatisfactory results with this reagent. 

Acetates. Complete acetylation of all the hydroxyl groups is desirable in order to avoid mixtures. In some cases, the completely acetylated sugars may be obtained in the a- and p-forms depending upon the catalyst, e.g., zinc chloride or sodium acetate, that is employed in the acetylation. The experimental details for acetylation may be easily adapted from those already given for a- and p-glucose penta-acetates (Section 111,137). 

It is important to use dry ethyl acetate, but it should contain 2-3 per cent, of alcohol. The so-called absolute or anhydrous ethyl acetate of commerce is satisfactory. Experimental details for the purification of 95-97 p>er cent, ethyl acetate are given in Section 11,47,29. 

Pelargonic acid (n-Nonoic acid), CH3(CH2),COOH. Equip a 1-litre, three-necked flask with a reflux condenser, a mercury-sealed stirrer, a dropping funnel and a thermometer. Place 23 g. of sodium, cut in small pieces, in the flask, and add 500 ml. of anhydrous n-butyl alcohol (1) in two or three portions follow the experimental details given in Section 111,152 for the preparation of a solution of sodium ethoxide. When the sodium has reacted completely, allow the solution to cool to 70-80° and add 160 g. (152 ml.) of redistilled ethyl malonate rapidly and with stirring. Heat the solution to 80-90°, and place 182 5 g. (160 ml.) of n-heptyl bromide (compare experimental details in Section 111,37) in the dropping funnel. Add the bromide slowly at first until precipitation of sodium bromide commences, and subsequently at such a rate that the n-butyl alcohol refluxes gently. Reflux the mixture until it is neutral to moist litmus (about 1 hour). 

Upon fusion with caustic alkah (for experimental details, see Section IV,33,2) and acidification of the aqueous extract, hydrogen sulphide is evolved (detected by lead acetate paper). This test is given by aU organic compounds of divalent sulphur (RSH, R SR" and R SSR"). 

The following experimental details were kindly supplied by Dr. J. Kenyon, F.R.S. 

Into a 1 litre round-bottomed flask, provided with a long (e.g., a 30 cm.) double surface condenser, place 22 -5 g. of clean sodium cut into small pieces (see Section Note 1, for experimental details concerning the... 

Prepare a solution of benzyl magnesium chloride in a 2-litre three-necked flask from 24-3 g. of magnesium turnings, 600 ml. of sodium-dried ether and 126-5 g. (115 ml.) of redistilled benzyl chloride follow the experimental details given under n-Propylbenzene (Section IV,7). Cool the flask in running water or in ice water. Place a solution of 456 g. of n-butyl-p-toluenesulphonate (Section IV,198) in about twice its volume of anhydrous ether in the dropping funnel, and add it slowly with stirring, at such a rate that the ether just boils a white solid soon forms. The addition is complete after about 2 hours. Pour the reaction product... 

The foUowing are typical experimental details for the preparation of naphthalene picrate. Dissolve 0 -1 g. of naphthalene and 0-2 g. of picric acid separately in the minimum volume of hot rectified spirit (about 2 ml.), mix the solutions and allow to cool. FUter and wash with 2 ml. of alcohol. RecrystaUise from hot alcohol, ethyl acetate or ether. 

Nitro derivatives. No general experimental details for the preparation of nitro derivatives can be given, as the ease of nitration and the product formed frequently depend upon the exact experimental conditions. Moreover, some organic compounds react violently so that nitrations should always be conducted on a small scale. The derivatives already described are usually more satisfactory for this reason the nitro derivatives have been omitted from Table IV,9. 

Place 18 g. (12 ml.) of fuming nitric acid, sp. gr. 1 5, and 30 g. (16-5 ml.) of concentrated sulphuric acid and a few fragments of broken glass in a 250 or 500 ml. round-bottomed flask. Add gradually, in small portions, 14 g. of p-nitrotoluene do not allow the temperature to rise above 50 and cool the flask, if necessary, by immersion in cold water. Place a small funnel in the mouth of the flask and heat on a water bath at 90-95° for 30 minutes. Allow to cool almost to the laboratory temperature and pour the reaction mixture slowly into about 500 ml. of ice water containing a few small pieces of ice. Filter the crude dinitrotoluene through a Buchner funnel at the pump, wash it thoroughly with cold water, and drain as completely as possible. RecrystalUse from the minimum volume of hot methyl alcohol (flask, reflux condenser, and water bath experimental details as in Section IV,12). The yield of pure 2 4-dinitrotoluene, m.p. 71°, is 12 -5 g. 

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