Double internal

When abrasive solids are present and it is not permissible to introduce appreciable quantities of a secondary flushing fluid into the process, double internal seals are sometimes used (Fig. 10-114). Both sealing faces are protected by the flushing fluid injected between them even though the inward flow is negligible. 

Cyclization of the two pendant alkyl side chains on barbiturates to form a spiran is consistent with sedative-hypnotic activity. The synthesis of this most complex barbiturate starts by alkylation of ethyl acetoacetate with 2-chloropentan-3-one to give 152. Hydrolysis and decarboxylation under acidic conditions gives the diketone, 153. This intermediate is then reduced to the diol (154), and that is converted to the dibromide (155) by means of hydrogen bromide. Double Internal alkylation of ethyl... 

A second method of assay of IAA has been developed by Mr. J. Cohen and involves a "double internal standard" usually 14C-IAA and 14C-indole-3-butyric acid (37). I will not discuss this method of assay except to indicate that it is possible to develop assays not involving mass spectrometry but with comparable sensitivity and good selectivity. 

Internal Rotation in Double Internal Rotor Molecules the Microwave Spectrum of Dimethyl Silane. J. chem. Physics 31, 547—548 (1959). 

Some decades ago, Swalen and Costain(1959), Myers and Wilson (1960) have extended the use of the symmetry point groups for studying the double internal rotation in acetone [1-2]. Dreizler generalized their considerations to two Csv rotor molecules with frames of a lower symmetry than C2U, and deduced their character tables [3]. 

From this character table, the symmetry eigenvectors for the double internal rotation in planar pyrocatechin are easily deduced on the basis of the double free rotor equation solutions ... 

Table 7 Character table for the double internal rotation in planar acetone with interaction between the rotors.

The restricted local Hamiltonian operator for the double internal rotation in acetone neglecting the cog-wheel effect between the rotors is similar to that of pyrocatechine (80), except for the periodicity of the rotor. The restricted local NRG is deduced directly from that of pyrocatechin (81), taking into account (42) [21-22] ... 

In the present paper, symmetry eigenvectors which factorize the Hamiltonian matrix into boxes are given for the single rotation in phenol (24) for double rotations in benzaldehyde (29), pyrocatechin (34) and acetone (44-46), for double rotation and inversion in non-planar pyrocatechin (40) and pyramidal acetone (49-51). In the same way, symmetry eigenvectors deduced in the local approach are deduced for some of these non-rigid systems (79), (83), and (89). Symmetry eigenvectors for the double internal Czv rotation in molecules with frame of any symmetry are given in reference [36]. 

In order to illustrate the power of the Group Theory for Non-Rigid Molecules, let us consider the double internal rotation problem in acetone, solved in [34]. This motion is described by a restricted Hamiltonian operator such as that of pyrocatechin (32) in which only the threefold periodicity of the potential for acetone (47) has been introduced ... 

With such a definition, the r-NRG for the double internal rotation in dimethylamine is a group of order 18 ... 

Simultaneous Gas Chromatographic Analysis for Diazepam and Its Major Metabolite, Desmethyldiazepam, with Use of Double Internal Standardization... 

Single or double International 0.875 Porous disc Short Guns... 

---