Yield, liquid table

The solvent-free 0-silylation can also be applied to liquid alcohols. Treatment of liquid alcohols 32-36 with various silyl chlorides at 60 °C for 5 h gave the corresponding 0-silyl ethers in good yields (Table 7). In this case, the steric bulkiness of the alcohol and reagent do not present any significant problem, except in the case of tertiary alcohols. 

The bulk of the naphtha was hydrotreated and catalytically reformed over a chlorided Pt/Al203-based catalyst to produce an aromatic motor gasoline. However, the hydrotreated Fischer-Tropsch naphtha is a poor feed for standard catalytic reforming on account of its high linear hydrocarbon content (>75%).37 In order to limit liquid yield loss, typical operation resulted in a reformate with quite low octane value (Table 18.10). Higher octane reformate could be produced, but at the expense of significant liquid yield loss. 

A modification of the Pinner reaction using liquid HF has been used to improve the yields of the dithioester products. The N-protected amino acid and peptide nitriles 6 dissolve in liquid HF at temperatures below 0°C and react with thiols to form the imidothioic acid ester hydrofluorides 7 that further react with H2S in pyridine at 0°C to form the dithioesters 8 (Scheme 2)J71 Several isotopic dithioesters have been synthesized by this method with improved yield (Table 2). The use of liquid HF at low temperature helps to dissolve the amino acid nitriles that are not very soluble under Pinner conditions (HCl-saturated CH2C12). 

Table IV shows the results. When the acidity is preferentially poisoned by equilibrating the catalyst with a feed containing 8 ppm of nitrogen, the following effects are noted (1) Total liquid yield increases by about 1 wt / (2) the jet fuel increases by 6 LV % ...

Analyses of coals which have been processed in the continuously operated pilot plants are listed in Table 1. Process liquid yields from the liquefaction step for these coals are shown in Figure 4 for different residence times in the liquefaction reactor. Longer residence time increases conversion of coal to liquids, but also increases hydrocracking of liquids to gas. 

As a result, there is an optimum time for each coal for maximizing liquid yield. An approximate explanation of these yields based on the coal analyses shown in Table 1 can be made. Higher yields correlate with high volatile matter, sulfur content, and reactive fractions and are, of course, inversely proportional to ash content. 

Gonzalez Gomez et al. (2002) applied crystallization fractionation to UCOME (Table 1.5). Following crystallization at a cooling rate = 0.1 °C/min, fractionation reduced CFPP from -1 to -5°C and total saturated FAME content from 19.2 to 14wt%. Again, liquid yields were low (25-30wt%). Krishnamurthy and Kellens (1996) reported that application of crystallization fractionation to TME increases iodine value (IV) from 41 to 60 and reduces CP from 11 to -1 °C with liquid yields of 60-65%. 

It can be observed from Table 2 that very low liquid yields were obtained compared to the results presented in the literature at similar experimental conditions such as in the study of Sakaki et al. [6]. As pointed out by Cahill et al. [7], these low liquid yields might be related to both the high-ash and high oxygen content present in the coal matrix - see Table 1. 

Table 4 summarizes the results of the liquid yield and conversion from SCFE of Butia coal with pure toluene at 623 K and at 3, 4 and 5 moLl 1 solvent density. The liquid yield and conversion figures are again lower than those reported in the literature for different coals. The conversion reached a maximum at 4 mol.1 1 this effect has been shown in the literature [8], though at higher pressures. More investigation is being carried out to clarify this effect. Since the experiments were accomplished at constant temperature - assuring the same depolymerization/thermolysis of the coal structure, the increase in the liquid yield and conversion could be attributed to an enhancement in solvent density (solvent power). 

Selenium tetrafluoride, which is a liquid at room temperature, reacts with aldehydes and ketones to form, gcm-difluoro compounds in good yields (Table 3). The reaction is run under mild conditions in halogenated solvents or without solvent. 

The clear liquid yielded saltpeter upon drying. The juxtaposition of these two methods—distillation vs. precipitation —relayed Geoffroy s hope that the laws of rapports could mediate between the different chemical procedures to shape a uniform terrain of chemical theory. By going through a variety of processes that produced corrosive sublimates, Geoffrey illustrated that the same order of rapports could explain all the varieties of chemical operations in a consistent manner. The theory of the process was the same, no matter what the variations in practice were. Through the example of corrosive sublimates, Geoffroy thus presented concisely and powerfully the descriptive, predictive, and explanatory functions of his table of rapports. 

Values illustrating product yields and gas compositions from isothermal experiments are shown in Table II. The yield data shown were obtained after a reaction period of two hours at a reaction temperature of 450°C. The gas and liquid yields are higher and the residue yield is lower when a catalyst is present. The gas compositions with and without catalyst are fairly similar. However 13C NMR analyses showed that the liquid products obtained in the catalyzed experiment have a higher aromatic content than those formed in the absence of the catalyst. 

Because of the broad scope of direct biomass pyrolysis, the basic technologies and principal products are tabulated in Table 8.12 to facilitate easy comparison. The conversion conditions and major products shown in this table are typical, but subject to considerable variation. There are several commonalities among the different pyrolysis methods. Pyrolysis time and temperature are clearly the key operating parameters that have the most influence on product yields and distributions. Moderate but optimized temperatures are needed at short residence times to maximize liquid yields, whereas long residence times and... 

Table I Operating conditions and total liquid yields for the experiments conducted.

Liquid yields, calculated as mass of product recovered divided by mass of rosin acid introduced in the reactor, range from 57 to 85 % C Table 2 ). There are significant differences between the catalysts employed. Catalyst A yields amounts of liquid product markedly lower than those obtained with catalyst B. This suggests that thp first catalyst favors cracking reactions whereas the second one does not, at least at the operating conditions explored. 

The effects of the three operating variables (temperature, hydrogen partial pressure and reaction time) on extent of hydrogenation have also been quantified following the same procedure as for liquid yield (as well as for the other response variables studied). Results, shown in Table 3 reveal that the three operating conditions also affect in the same way to both liquid yield and extent of saturation. Terr erature and duration of the... 

Compound 27b was subjected to the same reaction conditions as those for the cyclization of 27a to afford 28b in a better yield (60%, Table 5, Entry 4). The reaction under solid-liquid phase transfer conditions at 100°C using a catalytic amount of tetra- -butylammonium chloride (/7-BU4NCI) in N, A -dimethylformamide (DMF) [83] was found to be extremely effective to afford 28b in a much improved yield (Table 5, Entry 6, 77%). 

---