Khristo Ivanov ( bg, Христо Иванов) (3 May 1916 – 16 February 2004) was a

Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedon ...

organic chemist Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...

Life and career

Khristo Ivanov (Bulgarian: Христо Иванов) was born on 3 May 1916 in the town of Dobrich, Bulgaria. His father Ivan Khristov was a hardware man, who died in 1918 after having fought in

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, when Khristo Ivanov was just two. His mother, Elena Khristova, took care of her one and only son. Khristo Ivanov obtained his degree in chemistry from the Physico-Mathematical Faculty of

Sofia University Sofia University, "St. Kliment Ohridski" at the University of Sofia, ( bg, Софийски университет „Св. Климент Охридски“, ''Sofijski universitet „Sv. Kliment Ohridski“'') is the oldest higher education i ...

in 1939. After teaching Chemistry at school level in the towns of Popovo and

Karlovo Karlovo ( bg, Карлово ) is a historically important town in central Bulgaria located in a fertile valley along the river Stryama at the southern foot of the Balkan Mountains. It is administratively part of Plovdiv Province and has a p ...

for a few years, he acquired the position of regular Assistant Professor at the same faculty in 1946. He specialized in the field of

organic synthesis Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...

at the universities of Leipzig (1953–1954) and Moscow (1956–1957). His academic career is associated with the University of Sofia – its Physico-Mathematical Faculty and the later Faculty of Chemistry that branched off from it (1961). He received an Associate Professorship in 1957 and full Professorship and the Chair of

Organic Chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...

in 1963. Ivanov was Head of the Department of Organic Chemistry from 1963 until his retirement in 1984, Vice Rector of Sofia University (1962–1968), Dean of the Faculty of Chemistry (1972–1976). He was member of the Presidium (1980–1986) and later President of the Committee of Chemical Sciences of the

Higher Attestation Commission Higher Attestation Commission (russian: Высшая аттестационная комиссия, uk, Вища атестаційна комісія, abbreviated Cyrillic: ВАК, Latin: VAK) is a name of a national government agency in Russia, ...

. For the contribution to the advancement of science in his research, he was awarded the Cyril-and-Methodius medal (1st degree), the People's-Republic-of-Bulgaria medal (1st degree), and the Honorary medallion with Necklace of the "St. Kliment Ohridski" University of Sofia. Ivanov died on 16 February 2004 at the age of 87 after a short illness. On the occasion the 100th anniversary of hir birth a comprehensive biographical article was recently published.

Scientific works

Khristo Ivanov continued the research started by his predecessor Dimitar Ivanov of the

Bulgarian Academy of Sciences The Bulgarian Academy of Sciences (abbreviated BAS; bg, Българска академия на науките, ''Balgarska akademiya na naukite'', abbreviated ''БАН'') is the National Academy of Bulgaria, established in 1869. The Academy ...

, publishing over 125 scientific papers and raising the Bulgarian school of Organic Chemistry to an international level. His main interests focused on the reactivity of CH-acidic compounds in an attempt to solve fundamental problems in the chemistry of

carbanions In organic chemistry, a carbanion is an anion in which carbon is trivalent (forms three bonds) and bears a formal negative charge (in at least one significant resonance form). Formally, a carbanion is the conjugate base of a carbon acid: :R3C ...

and

organometallic compounds Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...

. The results obtained allowed the elaboration of various synthetic methods for preparation of new organic compounds. In collaboration with Peter Markov, Ivanov established for the first time the possibility for metalation of CH-acidic compounds with

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

in liquid

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...

. He attempted to clarify the structure of the prepared organomagnesium compounds and explained the obtained results with the phenomenon of metalotropy. In acknowledgement of these scientific achievements the team was given in 1979 the ''Prof. Asen Zlatarov Award'' by the

. The Laboratory of Organic Synthesis supervised by Ivanov also achieved a number of breakthroughs in organic synthesis. New synthetic methods were developed, involving the reaction of ambident nucleophilic reagents (prepared by metalation of esters,

nitriles In organic chemistry, a nitrile is any organic compound that has a functional group. The prefix ''cyano-'' is used interchangeably with the term ''nitrile'' in industrial literature. Nitriles are found in many useful compounds, including met ...

and amides of alkanoic and arylacetic acids) with N-acylated aldimines and ketimines. The resulting new derivatives of 3-acylaminopropanoic acids were transformed into various

heterocyclic compounds A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and ...

beta-lactams A beta-lactam (β-lactam) ring is a four-membered lactam. A ''lactam'' is a cyclic amide, and ''beta''-lactams are named so because the nitrogen atom is attached to the β-carbon atom relative to the carbonyl. The simplest β-lactam possible is ...

, 1,3-

oxazines Oxazines are heterocyclic compounds containing one oxygen and one nitrogen atom in a doubly unsaturated six-membered ring. Isomers exist depending on the relative position of the heteroatoms and relative position of the double bonds. By extension ...

, 2-imidazolidinones, etc. Ivanov and his lab studied in detail the reaction of 2-benzylbenzazoles with aromatic

aldehydes In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group ...

under phase-transfer

catalysis Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

or in aprotic

solvents A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for p ...

in the presence of a water solution of

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkali ...

leading to 2-styrylbenzazols or alcohols having a benzazole ring. Detailed studies have been done under the conditions of the Michael reaction on the addition of metallic derivatives of CH-acidic compounds to substrates containing

carbonyl In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containing a ...

or azomethine group or to substrates with an activated double bond. Ivanov was the initiator of studies on the reaction of nucleophilic reagents with

coumarins Coumarin () or 2''H''-chromen-2-one is an aromatic organic chemical compound with formula . Its molecule can be described as a benzene molecule with two adjacent hydrogen atoms replaced by a lactone-like chain , forming a second six-membered h ...

. A new interesting rearrangement of 3-substituted coumarins to 2-oxochromans-4-acetic acid derivatives was found for the first time. It is used for elaboration of preparative methods for conversion of nitriles, esters and amides of coumarin-3-carboxylic acid into the corresponding rearranged products.Anka Bojilova, Nestor Rodios, Rositsa Nicolova, Christo Ivanov; Reactions of 3-acyl-substituted 2H-1-benzopyran-2-ones with acid anhydrides, II. 1991, ''Liebigs Annalen der Chemie'', (12), pp. 1279–1284

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References

{{DEFAULTSORT:Ivanov, Khristo Bulgarian chemists 1916 births 2004 deaths People from Dobrich 20th-century Bulgarian scientists