Alkylation table

The trend in relative effectiveness of RAFT agents with varying Z is rationalized in terms of interaction of Z with the C=S double bond to activate or deactivate that group towards free radical addition. Substituents that facilitate addition generally retard fragmentation. O-Alkyl xanthates (Z=0-alkyl, Table... 

Table 10.6 is an approximate listing of groups in order of SnI and Sn2 reactivity. Table 10.7 shows the main reactions that proceed by the Sn2 mechanism (if R = primary or, often, secondary alkyl) Table 10.8 shows the main reactions that proceed by the tetrahedral mechanism. 

The simplicity of the two-phase modification of the Gabriel synthesis of primary amines, via the N-alkylation of potassium phthalimide, makes the procedure considerably more convenient than the traditional method, which normally requires the use of anhydrous dipolar aprolic solvents. The reaction can be conducted under solid liquid conditions using potassium hydroxide in toluene [25], or with preformed potassium phthalimide [26, 27] (cf ref. 28). As is normal for acylation reactions, relatively mild conditions are required for the preparation of the A-ethoxycarbonyl derivative [29], whereas a reaction temperature of 100°C is generally used for N-alkylation (Table 5.16). The reaction time for the soliddiquid two-phase system can be reduced dramatically with retention of the high yields, when the reaction mixture is subjected to microwave irradiation [30]. 

The use of a polyfunctional catalyst could enhance the life of the catalyst. A clear example is the use of H3PWi2O40-SO4 /ZrO2 mixtures for isobutane/ butenes alkylation (Table 13.4-). However, modifications of the t) pe of reactor could also favor extended catalyst longevity." During the last few years, other alternatives have been proposed that favor a better catalyst regeneration and/or lower catalyst deactivation the use of supercritical isobutene regeneration or dense-C02 enhanced the reaction media. ... 

Cumene was originally produced with SPA- [57], then FAU- or BEA-based catalysts, and most recently MWW. While most industrial processes use MWW-based catalysts [58], Dow and KeUog co-developed a dealuminated MOR based process called 3-DDM [59]. With each new process generation, conversion and selectivity to cumene has increased. These processes and the chemistry behind them are covered in Section 15.4. As the use of zeoHtes for alkylation reactions in industry increased, so did the study of the reaction and how the zeoHte topology affects the mechanism and selectivity to products, so that now many zeotypes are tested for aromatic alkylation as a way of figuring out a new structure s reaction pattern. Therefore, many zeotypes have been used to catalyze aromatic alkylation (Tables 12.9-12.11). 

Alkylation and deprotection of N-protected aminomethylphosphonate esters 6 are shown in Scheme 6. The nitrogen is protected as the imine derived from benzophenone or a benz-aldehyde, and a variety of conditions are used for deprotonation and alkylation (Table 2). The benzaldehyde imine of aminomethylphosphonate can be deprotonated with LDA and alkylated with electrophilic halides (entries 1 and 2). For the best yields, saturated alkyl bromides require an equivalent of HMPA as an additive. 36 Allylic esters can be added to the carbanion with palladium catalysis (entries 3-7). 37,38 For large-scale production, phase-transfer catalysis appears to be effective and inexpensive (entries 8-12). 39,40 ... 

A further group of biologically available chemical species comprises organic compounds of the trace elements, which may be divided into two groups organic complexes of cations, and metal and non-metal alkyls (Table 3). These species are mainly neutral molecules, in contrast to the ionic species identified in Table 2, and are thought to be taken up as a consequence of their lipid-solubility (Florence et al., 1983). 

Ca cation Introduction leads to the catalyst containing both kinds of catalytic sites, and the ethylene-isobutane Interaction over this catalyst proceeds through dimerization to the alkylation step, yielding high quality alkylate (Table V, column 4). The alkylate yield was 120X. The reaction does not occur unless transition metal cations are present In the catalyst even though the latter may contain acidic sites (CaY for example). It Is understood that no butenes are formed In this case, and ethylene does not Interact directly with Isobutane under the conditions of this experiment. 

Of the 78 survey responses only 22 reported that they routinely alkylate samples before sequencing. However, 49 facilities alkylated ABRF-94SEQ, of which 37 used solution and 12 attempted in situ alkylation. The remaining 29 facilities sequenced without alkylation. Table IV describes several methods of reduction and alkylation that were all provided with ABRF-94SEQ. An additional method using 3-bromopropyl-amine was employed by one respondent. Reduction in solution was performed with dithiothreitol (DTT) (68%), 2-mercaptoethanol (29%), and tributylphosphine (TBP) (3%). In situ reduction was carried out using DTT (50%) and TBP (50%). 

Lead tetra-alkyls containing one or two secondary radicles can easily be obtained by the action of lead alkyl mono- or dihalides on secondary magnesium alkyl halides, win 1st those containing three secondary radicles are derived ] )rimaril,y from the tctra-alkyls. Table XX. of the Appendix gives a list of these compounds, together with their physical constants. 

Propyidiethylsilane, the alkylated Table 1 Alkylation of E2 by Olefinic product, was found to be an n-propyl form Hydrocarbons and not iso form which was confirmed by NMR analysis. This clearly shows that the addition of propene to a Si atom undergoes at the terminal position of propene molecule. If propene activation by acid is an important process, secondary carbocation may produce and iso product could be produced. Hence the reaction mechanism is different from a typical Friedel-Crafts type reaction. 

The construction span is usually the functional span shown in Table 1 but not always since the construction span must include the constructed link and hence at least the a-carbon on both sides even though in some cases there is no product functionality on one synthon (/ = 0 in product, as in alkylation), e.g., acetylene alkylation (Table 1). 

The substituents R and R which have been introduced into the azo-methine group may be classified as acyl Table 6.2), alkyl Table 6.3) and a mixture of both of these types Table 6.4). 

---