Force-field calculations giving accurate conformation,. Delta. H sub f degree (T), S degree (T), and C sub p degree (T) for unsaturated acyclic and cyclic hydrocarbons

Journal Article · Thu Feb 23 00:00:00 EST 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100341a080· OSTI ID:5113201

Lenz, T G; Vaughan, J D ^[1]

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1. Colorado State Univ., Fort Collins (USA)

A modified version of the Boyd MOLBD3 force-field method has been employed to compute the structure, standard enthalpy of formation, and standard absolute entropy for a variety of dienes and unsaturated ring and methylene-bridged compounds. The modifications to MOLBD3 included incorporation of -ene and -diene parameters suggested by Anet and Yavari, as well as our adjustment of C(sp{sup 2})-C(sp{sup 2})-C(sp{sup 2}) and C(sp{sup 2})-C(sp{sup 2})-C(sp{sup 3}) bond angle parameters for unsaturated five-member rings and methylene-bridged compounds. Our MOLBD3 results for 1,3-butadiene, 1,3-pentadiene, 1,3-cyclohexadiene, 1,3-cycloheptadiene, cyclopentene, norbornane, norbornene, norbornadiene, bicyclo(3.2.1)octane, bicyclo(3.3.1)nonane, and 1,3-cyclopentadiene are generally in excellent agreement (typically {plus minus} 1 kcal/mol for {Delta}H{sub f}{degree}, and {plus minus} 1 cal/(mol{center dot}K) for S{degree}) with observed values and with calculations we and others have made with the Allinger MMP2 and Ermer-Lifson CFF-3 programs. These molecular mechanics methods are thus capable of predicting thermochemical properties with sufficient accuracy for useful thermodynamic calculations.

• DOE Contract Number: FG02-86ER13582
• OSTI ID: 5113201
• Journal Information: Journal of Physical Chemistry; (USA), Vol. 93:4; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BUTADIENE
STRUCTURAL CHEMICAL ANALYSIS
CYCLOALKENES
DIENES
NORBORNADIENE
PENTADIENES
PENTENES
CONFIGURATION INTERACTION
ENTROPY
EXPERIMENTAL DATA
FORMATION HEAT
MOLECULAR ORBITAL METHOD
MOLECULAR STRUCTURE
THERMODYNAMIC PROPERTIES
THERMODYNAMICS
ALKENES
DATA
ENTHALPY
HYDROCARBONS
INFORMATION
NUMERICAL DATA
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
POLYENES
REACTION HEAT
400201* - Chemical & Physicochemical Properties