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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A study of the aromatic cyclodehydration of 2-(2-naphthylmethyl)- 2'-chloro-5'-methylbenzophenone

Ojakaar, Leo January 1961 (has links)
In a recent study of cyclodehydrogenation reactions of potential carcinogenic or carcinolytic hydrocarbons Zajac pointed out that ring closure of 12-(3-methylphenyl)- benz[a]anthracene might take place at either of the two ortho positions or the phenyl ring. These positions are not equivalent with respect to the methyl group and ring closure might yield either 2-methyldibenzo[a,1]pyrene or 4-methyldibenzo[a,1]pyrene or both. The objectives of the present investigation are to study possibilities and methods to prepare 2-(2-naphthylmethyl)- 2'-chloro-5'-methylbenzophenone in a sufficient yield so that a study of the cyclization reaction under a variety of conditions can be made in order to prepare 2-methyldibenzo[a,l]pyrene. During the course of the investigation an improved synthetic route to prepare 2-bromonaphthalene was secured. Three methods utilizing Grignard reagents were approached in order to prepare 2-(2-naphthyl~ethyl)-2'halobenzophenones necessary for the study to obtain 2-(2-naphthylmethyl)-2'-chloro-5'-methylbenzophenone. The only successful preparative method for the above ketones was found to be the reaction between a Grignard reagent and an acid halide. This procedure was applied to the preparation of the following new ketones: 2-(2-naphthylmethyl)-2'-fluorobenzophenone, 2-(2-naphthylmethyl)- 2'-chlorobenzophenone, and 2-(2-naphthylmethyl)- 2'-chloro-5'-methylbenzophenone. Investigation of the sealed tube method revealed that the above ketones could be cyclized at 180° with a mixture of hydrobromic and acetic acids in seven hours. Under these conditions the new compounds 12-(2-fluorophenyl) benz[a]anthracene, 12-(2-chlorophenyl)benz[a]- anthracene, and 12-(2-chloro-5-methylphenyl)-7,12-dihydrobenzo[ a]anthracene were obtained. Further study showed that 12-(2-chloro-5-methylphenyl)-7,12-dihydro-benz[a]anthracene could be obtained in a much better yield when the above procedure was altered by using a mixture of hydriodic and acetic acids. In order to obtain 2-methyldibenzo[a,1]pyrene 12-(2-chloro-5-methylphenyl)-7,12-dihydrobenzo[a]anthracene was reacted with potassium hydroxide and quinoline. Although the results were not definite the qualitative tests and the ultraviolet and infrared spectra suggest an intermediate dihydro compound. The ultraviolet and infrared spectra of six new compounds were recorded. / Master of Science
2

The use of mineral oil as a trapping agent for volatiles produced by Ceratocystis moniliformis (Hedg.)

Whitehouse, Firth Kraft 03 March 2009 (has links)
Ceratocystis moniliformis grows well in a semi-synthetic liquid medium containing 30:1 glucose:yeast extract, vitamins, and minerals. At 25°C and 100 rpm on a rotary shaker, the culture grows and produces many pleasing and potentially useful fruity aroma-bearing compounds. A sensory evaluation panel described the aromas "banana," "citrus," "fruity," "peach," and "floral" in samples of this culture. However, yields of the compounds that cause these aroma perceptions are low, as their production is limited due to toxicity, or perhaps a feedback inhibition mechanism. Seventeen volatile aroma compounds were tentatively identified by Gas Chromatography - Mass Spectrometry (GC- MS), and of these, the production of isoamyl acetate, B -myrcene, acetophenone, i1-octanol, and geraniol was studied using GC analysis. In an attempt to increase the production of these compounds relative to the production level of aroma-bearing compounds obtained by traditional incubation methods, mineral oil was added to the growth medium as a thin (2 mm) layer. Difficulties in analyzing oil-free cultures made it impossible to directly compare yields in oil-free versus oil-containing cultures. However, the mineral oil acted as a trapping agent, and production of aroma compounds continued in the presence of mineral oil for up to 8 days, yielding from 246 to 2071 ug/100 ml culture of the aroma compounds. The above-mentioned compounds are similar to natural and synthetic essential oil components that are currently used as food flavorants. Thus, aroma-bearing compounds that are produced by Ceratocystis moniliformis may prove to be valuable alternative sources for food flavoring. / Master of Science

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