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Ring splitting

The penicillins are a large group of bactericidal compounds. They can be subdivided and classified by their chemical structure and spectrum of activity. The structure common to all penicillins is a (3-lactam ring fused with a thiazolidine nucleus (Fig. 45.1).The antimicrobial activity of penicillin resides in the (3-lactam ring. Splitting of the (3-lactam ring by either acid hydrolysis or (3-lactamases results in the formation of penicilloic acid, a product without antibiotic activity. Addition of various side chains (R) to the basic penicillin molecule... [Pg.528]

Clamp-ring (split-flange design) floating-head type 1 shell pass, 2 tube passes Area of heat-transfer surface 19.5m2 Shell -762 mm (30 in.)o.d. [Pg.202]

K. Peseke, S. Aldinger, and H. Reinke, An unusual C-l-C-3 ring-splitting of pyranosides by a retro-aldol reaction, Liebigs Ann. Chem., (1996) 953-957. [Pg.114]

In a different incident, a low-pressure tank 100 ft. (30 m) in diameter and over 40-ft. (12 m) high was distorted and the top ring split as a result of overfilling (see Figures... [Pg.28]

The anion radical of pyridinium bis(carbomethoxy)methylide (P —CXJ) exhibits non-equivalent ring splittings because the ester groups are non-equivalent... [Pg.140]

Vitamin D Is Derived from Cholesterol by the Ring-Splitting Aetivity of Light... [Pg.1089]

The major products from methyloxirane (propene oxide) are C2H5CHO, CH3COCH3 and CH2=CHCH20H [90], Similarly, isobutyraldehyde is the dominant product from isobutene oxide. Oxetanes are known to undergo homolysis through ring splitting, so that isobutene and HCHO are major products from 3,3-dimethyloxetane. [Pg.110]

FIGURE 21. The He(I) photoelectron spectrum of tetra-t-butyltetrahedrane. The twin peaks of low intensity at threshold are assigned to the le orbitals of the rings split by the dynamic Jahn-Teller effect. Bands of higher energy are overlapped by ionizations of the t-butyl groups... [Pg.241]

Side-chain elimination - Ring splitting Demethoxylation... [Pg.406]

Sinfelt, J.H. and Rohrer, J.C. "Kinetics of ring splitting of methylcyclopentane over alumina."/. Phys. Chem. 65 2272-2273 1961. [Pg.157]

Fig. 8. General mode of ring splitting (Humphrey, 1967) n-Atkane... Fig. 8. General mode of ring splitting (Humphrey, 1967) n-Atkane...
Trazodone is highly metabolized in the liver by hydroxylation, pyridine ring splitting, oxidation, and A -oxidation, with <1% of the unchanged drug appearing in the urine and feces. [Pg.189]

To explain the difference in the activity of isomers 563 and 565 Tanida used the concepts of Woodward-Hoffmann and Depuy about the mechanism of cyclopropane ring splitting. When the cyclopropane ring is open in both compounds the disrotatory process will proceed so that the electrons of the C —C bound could approach the tail part of the developing p-orbital at C . In isomer 565 the disrotation will occur outward, in isomer 563 inward in this case unfavourable steric interactions will result between the endo atoms and H. ... [Pg.230]


See other pages where Ring splitting is mentioned: [Pg.96]    [Pg.96]    [Pg.643]    [Pg.212]    [Pg.97]    [Pg.171]    [Pg.300]    [Pg.70]    [Pg.26]    [Pg.34]    [Pg.990]    [Pg.306]    [Pg.863]    [Pg.80]    [Pg.263]    [Pg.432]    [Pg.31]    [Pg.4]    [Pg.239]    [Pg.26]    [Pg.34]    [Pg.990]    [Pg.150]    [Pg.643]    [Pg.566]    [Pg.50]    [Pg.63]    [Pg.566]    [Pg.803]    [Pg.214]    [Pg.50]    [Pg.63]    [Pg.181]    [Pg.3]    [Pg.84]    [Pg.9]   
See also in sourсe #XX -- [ Pg.9 ]




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