THE CHEMICAL WORLD THIS WEEK
H o w e Lecturer Describes Synthesis, Structure of Patulin C&EN
REPORTS:
Harrison
Howe
Lecture
R O C H E S T E J L - T h e sixth lecture commemorating Harrison E . Howe, chemist, author, editor, naturalist, and h u m a n i tarian, was delivered by Robert Burns Woodward, -codiscoverer of a m e t h o d for synthesizing quinine. Held at Kodak Park o n N o v . 20, "Woodward's lecture on patulin, a mold-metabolic product, dealt with t h e attack o n its organic structure a n d synthesis.
means of careful physical measurement, he was able to check a n d eliminate t h e various possibilities. Synthesis of patulin mainly involved getting t h e skeleton together, for W o o d w a r d has found that it is usually possible to modify the skeleton. Several syntheses were developed following a series of complicated reactions, starting with b o d i tetrahydropyrone and with desoxypatulin.
W o o d w a r d attributed t h e success of t h e investigation to t h e scrutiny of every hypothesis from the point of view of its consistency with m o d e r n organic chemical theory a n d to liberal use of physical measurements. Thus, t h e work is illustrative of the power of present-day organic chemistry in the study of natural products. As patulin has proved t o be a poisonous compound, m u c h of t h e commercial interest has disappeared. An early report, since unsubstantiated, pointed to activity of patulin against the common cold a n d stimulated scientific curiosity. Woodward will b e c o m e a full professor of organic chemistry at Harvard University next July at the a g e of 3 4 years.
Organic Coatings A d v a n c e In Attack o n Corrosion C & E N REPORTS:
Woodward
delivers 1950 H o w e
Lecture
Isolated from a large number of microorganisms in 1942, early investigations postulated an incorrect structure based o n degradation studies by t h e Englishman, Raistrick. J n view of the importance of patulin in m e d i c i n e b e c a u s e of its marked antibiotic and antifungal properties, Woodward became interested in this previous work. Investigation of patulin structure would normally be t h o u g h t of a s difficult- the molecule is small a n d of t h e composition C7II0O4. However, degradation pro-ducts were obtained b y Raistrick and b»y Dutch workers which showed that there were as m a n y as five reactive positions ira the straight chain. From two principal d e g r a d a t i o n products, one a dill etopentane and the other a monoketopentane, f>oth h y d r a t i o n products of patulin, W o o d w a r d w a s able to postulate two structures o f importance.
O //
o
ti
ix
X
*' OH Patulin Measurements of absorption spectra m a d e it possible to eliminate one of these. T h u s , W o o d w a r d found t h a t even though the nurnfc>er of possible structures was great, modern o r g a n i c theory pointed to probable compounds involved a n d by
4260
Varnish and Paint C h e m i s t r y
N E W YORK.—Results of recent investigations in t h e field of organic coating chemistry and a colloquium on the protection of submerged surfaces against corrosion were featured at the third Varnish and Paint Chemistry Symposium held by t h e college of engineering, New York University, on Nov. 18. G. W . Oxley, Standard Oil Development Co., discussed coatings for protecting steel in water, particularly bituminous and asphaltic coatings, and outlined the experience of the oil industry in meeting corrosion problems. Bituminous coatings (asphalts a n d coal tars) are generally satisfactory for this purpose when coatings range in thickness from '/as to Vie inch. T h i n n e r applications usually experienced early failure. T h e asphalts and coal tars had shown outstanding waterproofing properties, t h e latter superior oil resistance. Mr. Oxley's paper said that zinc silicate paints, as demonstrated on mooring buoys, had r e n d e r e d very satisfactory service against corrosion. T h e use of vinyl resins in coating formulations has been accorded increased attention in recent years. For some applications the resin products had to be used in conjunction with sandblasting of the surfaces. Thixotropic coal tar products, applied under pressure, heath a r d e n e d phenolics, and metallic coatings like metallized zinc compounds, w e r e also employed in this research. T h e influence of the vehicle on the effect of coating materials was discussed during t h e colloquium by A. C. E l m , New Jersey Zinc Co. This paper took u p the molecular structure of protective films with special attention to those which can be rendered water-impermeable through the elimination of hydroxyl and carboxyl groups, or "water molecules." Baked films, hence, as a rule possessed more water resistance. Dr. Elm's discussion went into the effect of osmotic pressure, and t h e effect of electrolytic potentials across films. It was felt
CHEMICAL
Symposium
that it was more important for a paint film to be anticorrosive rather than waterresistant. A paper b y T. L. R o h w e d d e n and Fletcher Shanks, Rock Island District, U. S. Corps of Engineers, w h i c h w a s presented b y A. W. Henckeroth of the Fort Belvoir laboratories, outlined experiences with vinyl coatings on hydraulic structures in fresh water. After long experimentation with phenolics and vinyls it was found that vinyl chloride-acetate a n d other vinyl copolymers were promising. T h e vinyl systems were still affording protection after seven years' under-water exposure. F. E . Kulman, Consolidated Edison Co., described coating protection employed for underground cable a n d gas piping systems of his company in N e w York City. Based on a survey of t h e causes of corrosion underground, the requirements of a protective coating were listed a n d discussed. Thickness of coatings was d e e m e d an important factor. V. A. Veit, of t h e same company, outlined protective coatings for submersible-type transformers and network protectors and described t h e apparatus, typical installations, a n d exposures encountered, as well as coating failure. Spectra of Gels Max Kronstein, research associate, NYU college of engineering, presented n e w facts on t h e solid, insoluble, infusible, and limited-swelling products of polyhydroxyl alcohol-fatty acid esters. I n earlier NYU symposia papers he h a s shown that in t h e progress of the formation of this solid state as well as in the formation of the coherent gel form, certain characteristic changes occur in their diffraction x-ray spectrum. He now shows that this is not limited to gel-forming and film-forming oils, b u t that the same changes develop in t h e spectra of other gel- and film-forming materials such as alkyds, waxes, and certain plastics.
AND
ENGINEERING
NEWS
