has_part pimaric acid
In ___MASK39___ , esters are chemical compounds derived from an acid ( organic or inorganic ) in which at least ___MASK31___  OH ( hydroxyl ) group is replaced by an  O  alkyl ( alkoxy ) group . Usually , esters are derived from a carboxylic acid and an alcohol . Glycerides , which are fatty acid esters of glycerol , are important esters in biology , being ___MASK31___ of the main classes of lipids , and making up the bulk of animal fats and vegetable oils . Esters with low molecular weight are commonly used as fragrances and found in essential oils and pheromones . Phosphoesters form the backbone of DNA molecules . Nitrate esters , such as nitroglycerin , are known for their explosive properties , while polyesters are important plastics , with monomers linked by ester moieties . Rosin , also called colophony or Greek pitch , is ___MASK46___ ___MASK24___ form of resin obtained from pines and some other plants , mostly conifers , produced by heating fresh liquid resin to vaporize the volatile liquid terpene components . It is semi - transparent and varies in color from yellow to black . At room temperature rosin is brittle , but it melts at stove - top temperature . It chiefly consists of various resin acids , especially abietic acid . The term " colophony " comes from ', Latin for " resin from Colophon ," an ancient Ionic city . An organic compound is virtually any ___MASK78___ that contains ___MASK40___ , although a consensus definition remains elusive and likely arbitrary . Organic compounds are rare terrestrially , but of central importance because all known life is based on organic compounds . The most basic petrochemicals are considered the building blocks of organic chemistry . Resin acid refers to mixtures of several related carboxylic acids , primarily abietic acid , found in ___MASK68___ resins . Nearly all resin acids have the same basic skeleton : three fused ring fused with the empirical formula CHCOOH . Resin acids are tacky , yellowish gums that are ___MASK70___ - insoluble . They are used to produce soaps for diverse applications , but their use is being displaced increasingly by synthetic acids such as 2 - ethylhexanoic acid or petroleum - derived naphthenic acids . ___MASK14___ is a chemical ___MASK7___ with the symbol Sn ( for ) and atomic number 50 , is a post - transition metal in group 14 of the periodic table . It is obtained chiefly from the mineral cassiterite , which contains tin dioxide , SnO . ___MASK14___ shows a chemical similarity to both of its neighbors in group 14 , germanium and lead , and has two main oxidation states , + 2 and the slightly more stable + 4 . ___MASK14___ is the 49th most abundant ___MASK7___ and has , with 10 stable isotopes , the largest number of stable isotopes in the periodic table , thanks to its magic number of protons . It has two main allotropes : at room temperature , the stable allotrope is  - tin , a silvery - white , malleable metal , but at low temperatures it transforms into the less dense grey  - tin , which has the diamond cubic structure . Metallic tin is not easily oxidized in air . Terpenes are ___MASK46___ large and diverse class of organic compounds , produced by ___MASK46___ variety of plants , particularly conifers , though also by some insects such as termites or swallowtail butterflies , which emit terpenes from their osmeteria . They often have ___MASK46___ strong ___MASK58___ and may protect the plants that produce them by deterring herbivores and by attracting predators and parasites of herbivores . The difference between terpenes and terpenoids is that terpenes are hydrocarbons , whereas terpenoids contain additional functional groups . ___MASK5___ ( from " metabol ", " change ") is the ___MASK66___ of life - sustaining chemical transformations within the cells of living organisms . The three main purposes of metabolism are the conversion of food / fuel to energy to run cellular processes , the conversion of food / fuel to building blocks for proteins , lipids , nucleic acids , and some carbohydrates , and the elimination of nitrogenous wastes . These enzyme - catalyzed reactions allow organisms to grow and reproduce , maintain their structures , and respond to their environments . The ___MASK73___ metabolism can also refer to the sum of all chemical reactions that occur in living organisms , including digestion and the transport of substances into and between different cells , in which case the ___MASK66___ of reactions within the cells is called intermediary metabolism or intermediate metabolism . Tempera , also known as ___MASK95___ tempera , is a permanent , fast - drying painting medium consisting of colored pigments mixed with a ___MASK70___ - soluble binder medium ( usually a glutinous material such as ___MASK95___ yolk or some other size ). Tempera also refers to the paintings done in this medium . Tempera paintings are very long lasting , and examples from the 1st centuries AD still exist . Egg tempera was a primary method of painting until after 1500 when it was superseded by the invention of oil painting . A paint consisting of pigment and glue size commonly used in the United States as poster paint is also often referred to as " tempera paint ," although the binders and sizes in this paint are different from traditional tempera paint . In ___MASK39___ , a ketone ( alkanone ) is an organic compound with the structure RC (= O ) R ', where R and R ' can be a variety of ___MASK40___ - containing substituents . Ketones and aldehydes are simple compounds that contain a carbonyl group ( a ___MASK40___ - oxygen double bond ). They are considered " simple " because they do not have reactive groups like  OH or  Cl attached directly to the ___MASK40___ atom in the carbonyl group , as in carboxylic acids containing  COOH . Many ketones are known and many are of great importance in industry and in biology . Examples include many sugars ( ketoses ) and the industrial solvent acetone , which is the smallest ketone . Naphthenic acid ( CAS : ) ( NAs ) is the name for an unspecific mixture of several cyclopentyl and cyclohexyl carboxylic acids with molecular weight of 120 to well over 700 atomic mass units . The main fraction are carboxylic acids with ___MASK46___ ___MASK40___ backbone of 9 to 20 carbons . McKee et al . claim that " naphthenic acids ( NAs ) are primarily cycloaliphatic carboxylic acids with 10 to 16 carbons ." Salts of naphthenic acids , which are naphthenates , are widely used as hydrophobic sources of metal ions in diverse applications . 2 - Ethylhexanoic acid is the organic compound with the formula CH ( CH ) CH ( CH ) COH . It is ___MASK46___ carboxylic acid that is widely used to prepare lipophilic ___MASK45___ derivatives that are soluble in nonpolar organic solvents . 2 - Ethylhexanoic acid is ___MASK46___ colorless viscous oil . It is supplied as ___MASK46___ racemic mixture . Proteins ( or ) are large biomolecules , or macromolecules , consisting of ___MASK31___ or more long chains of amino acid residues . Proteins perform a vast array of functions within organisms , including catalysing metabolic reactions , DNA replication , responding to stimuli , and transporting molecules from ___MASK31___ location to another . Proteins differ from ___MASK31___ another primarily in their sequence of amino acids , which is dictated by the nucleotide sequence of their genes , and which usually results in protein folding into a specific three - dimensional structure that determines its activity . Abietic acid ( also known as " abietinic acid " or " sylvic acid ") is an organic compound that occurs widely in trees . It is the primary component of resin acid , is the primary irritant in pine wood and resin , isolated from rosin ( via isomerization ) and is the most abundant of several closely related organic acids that constitute most of rosin , the ___MASK24___ portion of the oleoresin of coniferous trees . Its ester or salt is called an " abietate ". Amino acids are biologically important organic compounds containing amine (- NH ) and carboxyl (- COOH ) functional groups , along with ___MASK46___ side - chain ( R group ) specific to each amino acid . The ___MASK62___ elements of an amino acid are ___MASK40___ , hydrogen , oxygen , and nitrogen , though other elements are found in the side - chains of certain amino acids . About 500 amino acids are known ( though only 20 appear in the genetic code ) and can be classified in many ways . They can be classified according to the core structural functional groups ' locations as alpha - (  -), beta - (  -), gamma - (  -) or delta - (  -) amino acids ; other categories relate to polarity , pH level , and side - chain group type ( aliphatic , acyclic , aromatic , containing hydroxyl or sulfur , etc .). In the form of proteins , amino acids comprise the second - largest component ( water is the largest ) of human muscles , cells and other tissues . Outside proteins , amino acids perform critical roles in processes such as neurotransmitter transport and biosynthesis . Oleoresins are semi - ___MASK24___ extracts composed of a resin in solution in an essential and / or fatty oil , obtained by evaporation of the solvent ( s ) used for their production . Naturally occurring oleoresins are also known as balsams . Vinegar is ___MASK46___ ___MASK21___ consisting of about 5  20 % acetic acid ( CHCOOH ), ___MASK70___ , and other trace chemicals , which may include flavorings . The acetic acid is produced by the fermentation of ethanol by acetic acid bacteria . Vinegar is now mainly used as ___MASK46___ cooking ingredient , or in pickling . As the most easily manufactured mild acid , it has historically had ___MASK46___ great variety of industrial , medical , and domestic uses , some of which ( such as its use as ___MASK46___ general household cleaner ) are still commonly practiced today . In ___MASK20___ chemistry and materials science , resin is a " ___MASK24___ or highly viscous substance " of plant or synthetic origin that is typically convertible into polymers . They are often mixtures of organic compounds , principally terpenes . Many plants , particularly woody plants , produce resin in response to injury . The resin acts as a bandage protecting the plant from invading insects and pathogens . An organic acid is an organic compound with acidic properties . The most common organic acids are the carboxylic acids , whose acidity is associated with their carboxyl ___MASK72___  COOH . Sulfonic acids , containing the ___MASK72___  SOOH , are relatively stronger acids . Alcohols , with  OH , can act as acids but they are usually very weak . The relative stability of the conjugate ___MASK16___ of the acid determines its acidity . Other groups can also confer acidity , usually weakly : the thiol ___MASK72___  SH , the enol ___MASK72___ , and the phenol ___MASK72___ . In biological systems , organic compounds containing these groups are generally referred to as organic acids . ___MASK46___ molecule is an electrically neutral group of two or more atoms held together by chemical bonds . Molecules are distinguished from ions by their lack of electrical charge . However , in quantum physics , organic ___MASK39___ , and biochemistry , the term " molecule " is often used less strictly , also being applied to polyatomic ions . Acetone ( systematically named 2 - propanone ) is the organic compound with the formula ( CH ) CO . It is ___MASK46___ colorless , volatile , flammable ___MASK21___ , and is the simplest ketone . ___MASK46___ carboxylic acid is an organic compound that contains ___MASK46___ carboxyl group ( ___MASK32___ (= O ) OH ). The general formula of ___MASK46___ carboxylic acid is R  COOH , with R referring to the rest of the ( possibly quite large ) molecule . Carboxylic acids occur widely and include the amino acids ( which make up proteins ) and acetic acid ( which is part of vinegar and occurs in metabolism ). Acetic acid , systematically named ethanoic acid , is ___MASK46___ colourless ___MASK21___ organic compound with the chemical formula CHCOOH ( also written as CHCOH or CHO ). When undiluted , it is sometimes called " glacial acetic acid ". Vinegar is roughly 3  9 % acetic acid by volume , making acetic acid the main component of vinegar apart from ___MASK70___ . Acetic acid has ___MASK46___ distinctive sour taste and pungent smell . In addition to household vinegar , it is mainly produced as ___MASK46___ precursor to polyvinyl acetate and cellulose acetate . Although it is classified as ___MASK46___ weak acid , concentrated acetic acid is corrosive and can attack the skin . Pimaric acid is ___MASK46___ carboxylic acid from the resin acid group . It can be prepared by dehydration of abietic acid , which it usually accompanies in mixtures like rosin . It is soluble in alcohols , acetone , and ethers . In ___MASK39___ isomerization ( also isomerisation ) is the process by which ___MASK31___ molecule is transformed into another molecule which has exactly the same atoms , but the atoms have a different arrangement e . g . A - B - ___MASK32___  B - A - ___MASK32___ ( these related molecules are known as isomers ). In some molecules and under some conditions , isomerization occurs spontaneously . Many isomers are equal or roughly equal in bond energy , and so exist in roughly equal amounts , provided that they can interconvert somewhat freely ; that is , the energy barrier between the two isomers is not too high . When the isomerization occurs intramolecularly it is considered a rearrangement reaction .