One of a large group of organic substances possessing the halocarbonyl group, in which X stands for fluorine, chlorine, bromine, or iodine. The terms acyl and aroyl halides refer to aliphatic or aromatic derivatives, respectively. The great inherent reactivity of acid halides precludes their free existence in nature; all are …
أكمل القراءة »Acetylene
An organic compound with the formula C2H2 or HC≡CH. The first member of the alkynes, acetylene is a gas with a narrow liquid range; the triple point is -81 °C (-114°F). The heat of formation (ΔHf) is +227 kilojoules/mole, and acetylene is the most endothermic compound per carbon of any …
أكمل القراءة »Acid base indicators
A substance that reveals, through characteristic color changes, the degree of acidity or basicity of solutions. Indicators are weak organic acids or bases which exist in more than one structural form (tautomers) of which at least one form is colored. Intense color is desirable so that very little indicator is …
أكمل القراءة »aceton
A chemical compound, CH3COCH3. A colorless liquid with an ethereal odor, it is the first member of the homologous series of aliphatic ketones. Its physical properties include boiling point 56.2°C (133.2°F). melting point -94.8°C (-138.6°F). and specific gravity 0.791. Acetone is used as a solvent for cellulose ethers, cellulose acetate, …
أكمل القراءة »Acetal
A geminal diether (R1 = H). Ketals, considered a subclass of acetals, are also geminal diethers (R1 = C, aliphatic or aromatic). Acetals are (1) independent structural units or a part of certain biological and commercial polymers, (2) blocking or protecting groups for complex molecules undergoing selective synthetic transformations, and …
أكمل القراءة »Acid and base
Two interrelated classes of chemical compounds, the precise definitions of which have varied considerably with the development of chemistry. Some of these controversies are still unresolved. Acids initially were defined only by their common properties as substances which had a sour taste, dissolved many metals, and reacted with alkalies (or …
أكمل القراءة »Accelerator mass spectrometry
The use of a combination of mass spectrometers and an accelerator to measure the natural abundances of very rare radioactive isotopes. These abundances are frequently lower than parts per trillion. The most important applications of accelerator mass spectrometry are in archeological and geophysical studies, as, for example, in radiocarbon dating …
أكمل القراءة »ABO blood groups زمر (أنواع فصائل) الدم
Blood group antibodies (A, B, AB, O) that can destroy red blood cells bearing the antigen to which they are directed; also called “agglutinins.” These red-cell antigens are the phenotypic expression of inherited genes, and the frequency of the four main groups varies in populations throughout the world. The antigens …
أكمل القراءة »Introduction to Organic chemistry: Chapter 2 NOTES
Introduction to Organic chemistry: Chapter 2 NOTES Acids and Bases A great many organic reactions are acid–base reactions. Many organic reactions are catalyzed by proton-donating acids, such as H3O+ and CH3OH2+. Others are catalyzed by Lewis acids, such as AlCl3 . 2.1 What Are Arrhenius Acids and Bases? According to …
أكمل القراءة »addition reaction
addition reaction or addition any organic chemical reaction involving the combination of two or more substances to form a single product in which there are more groups attached to carbon atoms than there were in the original reactants. Such reactions thus involve a net reduction of bond multiplicity in one …
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