Dilute solution parameters of polymethylphenylsiloxamers

Dilute solution parameters were determined for polymethylphenylsiloxamer fractions (5 × 10⁴ < M < 1.5 × 10⁶) in toluene, cyclohexane, and diisobutylamine (θ ≈ 30.4°C). The data are interpreted by the procedure suggested by Flory and Fox. Minor deviations from theory are noted. Polymers from both cis- and trans-cyclotrisiloxanes were investigated. The major portion of the work, however, was concentrated on fractions derived from the trans form. From the data obtained, a characteristic ratio of dimensions (r /r )^½ of 1.56 was determined. The hydrodynamic parameter Φ was determined to be (2.0 ± 0.3) × 10²¹. The appropriate model for the polymer is indicated to be the impermeable random coil with slight hindrance to rotation about backbone skeletal bonds.     

The crystal structure of racemicdl-penicillamine and a spectroscopic study ofd-(−)-penicillamine

The X-ray crystal structure of a racemic mixture of D- and L-penicillamine has been determined. Crystals are monoclinic,P2₁/c (No. 14), with cell dimensionsa=11.624(3),b=5.919(1),c=11.482(2) Å,β=114.48(2)°, andZ=2, based on the racemate. The structure was determined by standard methods and refined toR ₁=0.0666,R ₂=0.0726 for 985 independent reflections. Bond lengths and bond angles do not differ from those in similar structures. Mass spectra and¹H and¹³C NMR spectra are reported ford-penicillamine, and detailed infrared and Raman spectra are reported for solidd-penicillamine hydrochloride,d ₅-d-penicillamine hydrochloride,d-penicillamine,d ₄-d-penicillamine, anddl-penicillamine. The Raman spectrum ofd-penicillamine in H₂O solution as a function of pH is also reported.     

Triol protection with 6-benzoyl-3,4-dihydro-(2H)-pyran

6-Benzoyl-3,4-dihydro-(2H)-pyran will protect 1,2,3-triols such as glycerol as their corresponding spiro-[5-phenyl-3,6,8-trioxabicyclo[3.2.1]octane-4,2[prime or minute]-tetrahydropyran]s and 1,2,4-triols (less efficiently) as the corresponding trioxabicyclo[3.2.2]nonanes; the hexol mannitol is converted into the corresponding bis-protected product.     

Laser shadowgraph and schlieren studies of gravity-related flow during solidification

Shadowgraph and schlieren techniques were used to observe gravity-related flow arising during solidification. The purpose of these studies was to elucidate the results of previous low gravity solidification experiments. Shadowgraph and schlieren techniques were selected as most suitable for operation in the anticipated experimental environment. A laser shadowgraph/schlieren system was built and flown on KC-135 low gravity simulation flights. A solution of ammonium chloride and water was cooled during the experiment, causing solidification. Growth plumes in the solution were observed and photographed using shadowgraph and schlieren techniques. Results are presented and related to previous work.