N,AT-Bis

In 1995, Mandal et al. [151] described the crystal structure of N,AT-bis-(p-butoxybenzylidene)-a,a -bi-p-toluidine. They found that the two symmetrical fractions of the molecule are almost planar, but the angle between these planes is 63.5°. The molecules are arranged in tilted layers. This tilted layer-like structure is referred as a precursor to the tilted smectic phase. 

HN-3 CeH ClsN tris(2-cbloroetbyl) amine 2,2, 2"-tricblorotrietbylamine tris(2-cbloroetbyl)amine HN-3 2-cbloro-N, AT-bis(2-cbloroetbyl)etbanamine N-metbyl lost... 

The N,AT-bis(trimethylsilyl)benzarnidinate zirconium dichloride complexes [rj2-4-RC6H4C(NSiMe3)2]2ZrCl2 (R=H (1) or CH3 (2)) were prepared by the reaction of ZrCl4 with two equivalents of bis(trimethylsilyl)benzamidinate lithium-TMEDA (TMEDA=AT,iV,iV/,iV/-tetramethylenediamine) at room temperature in toluene yielding, after removal of the TMEDA and crystallization, 83-89% of pale yellow analytically pure rhombohedral crystals of 1 and 2 (Scheme 1) [31,33]. These complexes were also obtained in a high quality form... 

Kricheldorf has reported the synthesis of lyotropic poly(amide-imide)s and poly(benzoxazole-amide)s. These were prepared by the polycondensation of N,N-bis(trimethylsilyl)-p-phenylenediamine or N,AT -bis(trimethylsilyl)-3,3 -dim-ethylbenzidine with the diacyl chloride of trimellitimide of p-aminobenzoic acid, or the imide formed from p-amino benzoic acid and terephthalic acid. Lyotropic behaviour was observed in cone, sulphuric acid solution [38]. A series of thermotropic poly(imide-amide)s was prepared based on trimellitimides formed from trimellitic anhydride and an a, -bis(4-aminophenoxy) alkane with carbon chain lengths 9-12. Melting points were in the range 250-300 °C. They formed smectic A phases and tended to degrade around the isotropisation temperatures (around 350 °C). Pendant methyl groups or occupied meta- groups tended to prevent mesophase formation [39]. Novel LC poly(imide-amides) have also been synthesised from new diamine spacers derived from linear diaminoalkanes and 4-nitrophthalic anhydride. A smectic and nematic phase were observed when 4,4 -biphenyl dicarboxylic acid was used as co-monomer [40]. 

From Eq. (1-17), we can see that the torque tends to turn m toward B. This means that the loop (.0=0) shown in Fig. l-5(a) is more stable than that (B> 0) shown in Fig. l-5(b). In other words, N tends to decrease 0 and the magnitude of N at Bis represented by... 

Aliphatic—aromatic poly(amide—imides) based on N,1S7-bis(carboxyalkyl)-benzophenone-3,3, 4,4 -tetracarboxyhc diimides have shown a 10% weight loss at 400°C (14). 

N,N-bis(4-methylphenyl)-N,iV-bis(4-ethylphenyl)-[l,l -(3,3 -dimethyl)biphenyl]-4,4 -diamine [115310-63-9] (ETPD) (8) -doped PMPS (Table 1, entry 22), hole mobihty approaching 10 cm /Vs at 2.5 x 10 V/cm was observed (48). This is the highest recorded hole mobihty for disordered organic systems. From this perceptive, it is very interesting to study the carrier mobihty of polymers heavily doped with semiconductor nanoclusters. 

N,]S7-bis(methoxymethyl)uron was first isolated and described in 1936 (41), but was commercialized only in 1960. It is manufactured (42) by the reaction of 4 mol of formaldehyde with 1 mol of urea at 60°C under highly alkaline conditions to form tetramethylolurea [2787-01-1]. After concentration under reduced pressure to remove water, excess methanol is charged and the reaction continued under acidic conditions at ambient temperatures to close the ring and methylate the hydroxymethyl groups. After filtration to remove the precipitated salts, the methanolic solution is concentrated to recover excess methanol. The product (75—85% pure) is then mixed with a methylated melamine—formaldehyde resin to reduce fabric strength losses in the presence of chlorine, and diluted with water to 50—75% soHds. Uron resins do not find significant use today due to the greater amounts of formaldehyde released from fabric treated with these resins. 

In the other extreme, ethyl 3-oxohexanoate 75 required fusion with 3-pyridyl-hydrazide 73a or 3-hydrazinocarbonyl-pyridine-l-oxide 73b at 120°C in order to give the corresponding pyrazol-3-ones 76a,b (92AF1350) (Scheme 22). Depending on the reaction conditions, the reaction of ethyl 3-oxo-3-phenylpropanoate 77 and cyanomethylhydrazide 78 gave different products. Thus, fusion at 140°C gave pyrazol-3-one 79 and N,A -bis(cyanoacetyl)hydrazine 80, while heating in ethanol... 

Preparation of 7-(D-0t-phenyigiycyiamido)-3-chioro-3-cephem-4-carboxyiic acid To a suspension of 280 mg (1.2 mmol) of 7-amino-3-chloro-3-cephem-4-carboxylic acid in 14 ml of acetonitrile was added with stirring at room temperature 0.5 ml of N, 0-bis-(trimethylsilyl)acetamide to form the soluble disilylmethyl derivative thereof. The solution was cooled to 0°C and was slowly added to a solution of the mixed anhydride formed by reacting 408 mg (1.5 mmol) of methyl-3-a-carboxybenzylaminocrotonate sodium salt with 161 mg (1.7 mmol) of methyl chloroformate in the presence to 2 drops of N, N-dimethylbenzyl amine in 7 ml of acetonitrile. 

Thioethers 210 are smoothly formed upon cyclization of silyl nitronates 209, generated in situ from the nitro compounds 208, on treatment with N,0-bis(trimethylsilyl)acetamide (BSA, Scheme 24) [57]. Fluorodesilylation of 210 gave the AT-oxide 212, presumably via highly reactive aldehyde 211, which was reduced to the target compound actinidine 213 in an overall 27% yield. 

Silylated pyrrohdone 388 reacts with formaldehyde to give 429 [41] whereas N-trimethylsilylsucdnimide 201 reacts with formaldehyde only in the presence of MesSiONa 96 at 100°C to give N-trimethylsilyloxymethylenesuccinimide ]42]. The silylating agent BSA 22a with formaldehyde at 75 °C gives the 0,N-acetal 430 [41]. Hydrated ninhydrin 431 is converted by N,0-bis-(trimethylsilyl)acetamide 22 a to the 0,N-acetal 432 ]43] (Scheme 5.12). 

Silylation of hydroxylamine or N-alkyl or N-ethoxycarbonyUiydroxylamines is usually accomphshed, in 52-84% yield, by silylation with TCS 14/NEt3 [63, 161, 162]. Whereas the reaction of N,0-bis(trimethylsilyl)methylhydroxylamine 952 with aldehydes such as benzaldehyde, or with ketones, with to adducts such as 953, has already been mentioned at the beginning of Section 7.3 thermal and other reactions of N,0-bis(trimethylsilyl)hydroxylamine 1141 or N-substituted N,0-bis(trimethylsi-lyl)hydroxylamines 1121, 1128, 1131 are discussed in this section. 

N,0-bis(trimethylsilyl)acetamide (BSA, 22 a 2.5 mmol) is added to 1-nitro-naphthalene 1026 (1 mmol) and sulfone 1027 (1 mmol) in acetonitrile (2 mL) and the resulting mixture is stirred until dissolution occurs. After addition of DBU (776 pL, 5 mmol, in one portion) the reaction mixture is stirred at room temperature for 24 h then poured into a cold aqueous solution of NH4CI in H2O and extracted with CH2CI2 (3x20 mL). The extracts are washed with 20 mL brine, dried with MgS04, and evaporated. On addition of 3 mL chloroform crystalline 1028, m.p. 227-228°C (82%) is obtained [97] (Scheme 7.64). 

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